CN105355926A - Air cathode, preparation method of air cathode and microbiological fuel cell - Google Patents
Air cathode, preparation method of air cathode and microbiological fuel cell Download PDFInfo
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- CN105355926A CN105355926A CN201510728798.6A CN201510728798A CN105355926A CN 105355926 A CN105355926 A CN 105355926A CN 201510728798 A CN201510728798 A CN 201510728798A CN 105355926 A CN105355926 A CN 105355926A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/8605—Porous electrodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/88—Processes of manufacture
- H01M4/8825—Methods for deposition of the catalytic active composition
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Abstract
The invention provides an air cathode. The air cathode comprises a catalyst layer containing nitrogen-doped graphene, and a diffusion layer. The nitrogen-doped graphene provides a catalyst layer with good catalysis performances for the air cathode. The air cathode can be prepared by simple and convenient processes. The catalyst layer can be roll-molded without a binder so that electrode performances of the air cathode can be improved.
Description
Technical field
The present invention relates to environment, material, energy field, particularly, the present invention relates to air cathode, prepare the method for air cathode, microbiological fuel cell and the microbiological fuel cell purposes in process aqueous medium.
Background technology
Environmental problem and energy problem are that contemporary society develops two hang-ups faced, and taking into account energy recovery while purifying waste water is new challenge faced by sewage disposal technology.Microbiological fuel cell is a kind of emerging sewage disposal technology, can be electric energy by the chemical energy in pollutant while disposing of sewage, utilize the electrogenesis microbe being attached to anode by the oxidation operation in sewage, negative electrode accepts electronics and completes oxygen reduction reaction simultaneously.In the negative electrode of microbiological fuel cell, air cathode owing to can realize direct diffusion, the mass transfer of oxygen in air, and saves a large amount of aeration energy consumption and receives extensive concern.
But, still have much room for improvement for the air cathode of microbiological fuel cell and the catalytic efficiency of microbiological fuel cell and battery performance at present.
Summary of the invention
The application makes the discovery of the following fact and problem and understanding based on inventor:
In current air cathode, the problem of ubiquity preparation process complexity, needs electrode material repeatedly to be rubbed the operations such as pressure or brushing to make it shaping usually.And because preparation process is complicated, usually need larger catalyst material load capacity when Kaolinite Preparation of Catalyst layer, so that the demand met in the preparation process of air cathode and air cathode itself are for the requirement of catalytic performance.Inventor finds through further investigation and great many of experiments, this is because mostly the material of formation catalyst layer is dusty material, therefore needing the process preparing air cathode to carry out series of formed process to it, this dusty material can be compound in air cathode.In addition, need to add binding agent to strengthen the contact of catalyst layer material in the process of Kaolinite Preparation of Catalyst layer, and forming processes can be carried out by which better methods such as rubbing pressure, vertical compression, brushing.But above-mentioned binder material is generally the insulator of electronics, therefore the interpolation of binding agent also can cause certain influence to the electric conductivity of air cathode.
The present invention is intended to solve one of technical problem in correlation technique at least to a certain extent.
In a first aspect of the present invention, the present invention proposes a kind of air cathode.According to embodiments of the invention, this air cathode comprises: catalyst layer, and described in described catalyst layer, catalyst layer contains nitrogen-doped graphene; And diffusion layer.Thus, can by nitrogen-doped graphene for this air cathode provide the catalyst layer with good catalytic, and this air preparation process is easy, catalyst layer carries out rubbing molded without the need to adding binding agent, and then can improve the electrode performance of this air cathode.
According to embodiments of the invention, this air cathode can also have following additional technical feature one of at least further:
According to embodiments of the invention, this air cathode comprises further: current collection layer, wherein, described current collection layer is formed by stainless steel, described current collection layer is arranged between described diffusion layer and described catalyst layer, or described catalyst layer and described diffusion layer are arranged on the same side of described current collection layer.Thus, the electric conductivity of this air cathode can be strengthened by current collection layer, and then improve the performance of this air cathode further.
According to embodiments of the invention, this air cathode comprises further: supporting layer, and described supporting layer is arranged between described diffusion layer and described catalyst layer, and described supporting layer is formed by stainless steel.Thus, reliable support can be provided for this air cathode.
According to embodiments of the invention, described catalyst layer is formed in the side of described current collection layer, and described supporting layer is formed in the side of described catalyst layer away from described current collection layer, and described diffusion layer is formed in the side of described supporting layer away from described catalyst layer.Thus, good support and protection can be provided by current collection layer and supporting layer for catalyst layer and diffusion layer, improve the electrode conductivuty of this air cathode simultaneously, and then the electrode performance of this air cathode can be improved further.
According to embodiments of the invention, in this air cathode, not containing binding agent in described catalyst layer.Thus, the electric conductivity of catalyst layer can be improved, and then improve the electrode performance of this air cathode further.
According to embodiments of the invention, in this air cathode, in described catalyst layer, the load capacity of described nitrogen-doped graphene is not more than 2.5 μ g/cm
2.Inventor finds, according in the air cathode of the embodiment of the present invention, good catalytic effect can be issued in the prerequisite that catalyst layer catalyzes active component content is less, thus, save the production cost of this air cathode, and ensure that the electrode performance of this air cathode is unaffected.
According to embodiments of the invention, described catalyst layer comprises described catalyst layer and comprises metallic substrates and described nitrogen-doped graphene, and described nitrogen-doped graphene load is in described metallic substrates.Thus, can using the metallic substrates containing nitrogen-doped graphene directly as catalyst layer, and then avoid complicated forming operation, and owing to containing metallic substrates in this catalyst layer, and then further increase the electric conductivity of catalyst layer, and then the electrode performance of this air cathode can be improved further.
According to embodiments of the invention, in this air cathode, described catalyst layer is formed through the following steps: the quartz boat containing described metallic substrates is placed in airtight reaction compartment, wherein, described metallic substrates comprise nickel screen and nickel foam one of at least; Under 250 ~ 300 degrees Celsius, in described reaction compartment, pass into inert gas, to discharge the air in described reaction compartment; Temperature in described reaction compartment is increased to 800 ~ 1200 degrees Celsius, and in described reaction compartment, pass into hydrogen, the flow-rate ratio of described hydrogen and described inert gas is 1:40 ~ 1:1000 simultaneously; And liquid precursor is supplied in described reaction compartment, described liquid precursor comprise be selected from acetonitrile, pyridine and pyrroles one of at least, the flow velocity of described liquid precursor is 2 ~ 1000 μ l/min, the service time of described liquid precursor is 2 ~ 60 minutes, so that nitrogen-doped graphene described in load in described metallic substrates, and then obtain described catalyst layer.Thus, the nitrogen-doped graphene with nickel screen can be obtained easily, and then the electrode performance of this air cathode can be improved further.
In another aspect of this invention, the present invention proposes a kind of method preparing air cathode.According to embodiments of the invention, the method comprises: (1) is load nitrogen-doped graphene on the metallic substrate, to obtain catalyst layer; And (2) arrange diffusion layer in the side of described catalyst layer, to obtain described air cathode.Thus, the efficiency and the effect that utilize the method to prepare air cathode can be improved.
According to embodiments of the invention, the method can also have following additional technical feature one of at least further:
According to embodiments of the invention, described catalyst layer is formed by following steps: the quartz boat containing described metallic substrates is placed in airtight reaction compartment, wherein, described metallic substrates comprise nickel screen and nickel foam one of at least, under 250 ~ 300 degrees Celsius, in described reaction compartment, pass into inert gas, to discharge the air in described reaction compartment, temperature in described reaction compartment is increased to 800 ~ 1200 degrees Celsius, and in described reaction compartment, pass into hydrogen, the flow-rate ratio of described hydrogen and described inert gas is 1:40 ~ 1:1000 simultaneously, and liquid precursor is supplied in described reaction compartment, described liquid precursor comprises and is selected from acetonitrile, pyridine and pyrroles one of at least, the flow velocity of described liquid precursor is 2 ~ 1000 μ l/min, the service time of described liquid precursor is 2 ~ 60 minutes, so that nitrogen-doped graphene described in load in described metallic substrates, and then obtain described catalyst layer, described diffusion layer is formed by following steps: get carbon black and teflon mixture that mass ratio is 2:3, add ethanol and in 80 C water bath ultrasonic 10 ~ 30 minutes to forming mixture of viscous form, described mixture of viscous form is carried out forming processes, to obtain described diffusion layer.Thus, the efficiency and the effect that utilize the method to prepare air cathode can be improved.
According to embodiments of the invention, before described diffusion layer is set, pre-set current collection layer, described current collection layer is formed by stainless steel, wherein, described current collection layer is arranged between described diffusion layer and described catalyst layer, or described catalyst layer and described diffusion layer are arranged on the same side of described current collection layer.Thus, efficiency and the effect of the air cathode utilizing the method to prepare can be improved further.
According to embodiments of the invention, the method comprises further: arrange supporting layer, and described supporting layer is arranged between described diffusion layer and described catalyst layer, and described supporting layer is formed by stainless steel.Thus, efficiency and the effect of the air cathode utilizing the method to prepare can be improved further.
In still another aspect of the invention, the present invention proposes a kind of microbiological fuel cell.According to embodiments of the invention, this microbiological fuel cell comprises: housing, limits reaction compartment in described housing; Anode, described anode is arranged in described reaction compartment; Electrogenesis microbe, described electrogenesis microbial adhesion is at the outer surface of described anode; And foregoing air cathode, described air cathode is arranged in described reaction compartment, and described air cathode is electrically connected with described anode.Thus, the result of use of the microbiological fuel cell utilizing this air cathode as cell cathode can be improved.
In still another aspect of the invention, the present invention proposes the purposes of previously described microbiological fuel cell in process aqueous medium.Thus, microorganism fuel cell processing example can be utilized as aqueous mediums such as sewage, and then efficiency and the effect of sewage disposal can be improved.
Accompanying drawing explanation
Fig. 1 shows the structural representation of air cathode according to an embodiment of the invention;
Fig. 2 shows the structural representation of air cathode in accordance with another embodiment of the present invention;
Fig. 3 shows the structural representation of the air cathode according to another embodiment of the present invention;
Fig. 4 shows the structural representation of the air cathode according to another embodiment of the present invention;
Fig. 5 shows the structural representation of microbiological fuel cell according to an embodiment of the invention;
Fig. 6 shows the electron scanning micrograph of the catalyst layer according to the embodiment of the present invention;
Fig. 7 shows the electron scanning micrograph of the catalyst layer according to the embodiment of the present invention;
Fig. 8 shows Raman spectrogram according to the nitrogen-doped graphene of the embodiment of the present invention and analysis chart;
Fig. 9 shows x-ray photoelectron power spectrum (XPS) the test result figure of nitrogen-doped graphene according to an embodiment of the invention;
Figure 10 shows the air cathode electrochemistry linear scanning volt-ampere curve according to the embodiment of the present invention;
Figure 11 shows the microbiological fuel cell current density-surface power density curve chart according to the embodiment of the present invention;
Figure 12 shows the microbiological fuel cell current density-cathode potential curve figure according to the embodiment of the present invention;
Figure 13 shows the microorganism fuel cell cathode internal resistance block diagram according to the embodiment of the present invention;
Reference numeral:
10: catalyst layer
20: diffusion layer
30: current collection layer
40: supporting layer
100: housing
200: anode
300: negative electrode
400: electrogenesis microbe
Embodiment
Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings.Be exemplary below by the embodiment be described with reference to the drawings, be intended to for explaining the present invention, and can not limitation of the present invention be interpreted as.
In one aspect of the invention, the present invention proposes a kind of air cathode.Below the concrete structure of this air cathode is described in detail.With reference to figure 1, according to embodiments of the invention, this air cathode comprises: catalyst layer 10 and diffusion layer 20.Particularly, catalyst layer 10 comprises nitrogen-doped graphene, to improve the catalytic effect of catalyst layer 10; Diffusion layer 20 is for promoting the transmission of oxygen and preventing aqueous water from overflowing from air cathode.Particularly, according to embodiments of the invention, the diffusion layer 20 of this air cathode contacts with air (not shown), the oxygen in air is delivered in air cathode, and utilize catalyst layer 10 catalytic oxygen generation reduction reaction, and then realize the using function of this air cathode.Thus, can by nitrogen-doped graphene for this air cathode provide the catalyst layer with good catalytic, and this air preparation process is easy, catalyst layer carries out rubbing molded without the need to adding binding agent, and then can improve the electrode performance of this air cathode.
According to embodiments of the invention, catalyst layer 10 can comprise metallic substrates and nitrogen-doped graphene, and wherein nitrogen-doped graphene load on the metallic substrate.Such as, according to embodiments of the invention, this metallic substrates can be nickel screen or nickel foam.Thus, the nickel screen containing nitrogen-doped graphene can be adopted directly to use as catalyst layer 10, nitrogen-doped graphene can catalytic oxygen generation reduction reaction as the material with catalytic activity, and metallic substrates is owing to having good conductive capability, and good chemical stability, therefore can improve the electric conductivity of this air cathode further.Thus, can to avoid in the process of Kaolinite Preparation of Catalyst layer 10 required a series ofly rubbing molded operation, directly the metallic substrates containing nitrogen-doped graphene can be cut into size and the shape of needs, with other part composite moldings of air cathode.Thus, the technique of this air cathode of preparation can be simplified further.
In addition, according to embodiments of the invention, in the catalyst layer 10 of this air cathode, the load capacity of nitrogen-doped graphene is not more than 2.5 μ g/cm
2(according to the conversion of negative electrode projected area).In current air cathode, the load capacity of catalyst layer is generally and is not less than 3mg/cm
2, according in the air cathode of the embodiment of the present invention, the load capacity of catalyst decreases 3 orders of magnitude compared with the load capacity of catalyst in current air cathode, and the air cathode that the present invention simultaneously proposes can also obtain good power density.Inventor finds, according in the air cathode of the embodiment of the present invention, good catalytic effect can be issued in the prerequisite that catalyst layer catalyzes active component content is less, and then save the production cost of this air cathode, and ensure that the electrode performance of this air cathode is unaffected.In addition, according to embodiments of the invention, not containing binding agent in this catalyst layer 10.Because catalyst layer 10 is formed on the metallic substrate by nitrogen-doped graphene load, therefore compared with traditional dusty material, not needing to add binding agent in the process of Kaolinite Preparation of Catalyst layer 10 makes catalytically-active materials shaping or utilize binding agent that catalyst layer 10 is bonded with other parts of air cathode, can directly according to the actual requirements, metallic substrates containing nitrogen-doped graphene is cut into corresponding shape, directly combines as catalyst layer 10 other parts with this air cathode.Thus, can avoid if the binding agents such as polytetrafluoroethylene are for the impact of catalyst layer 10 conductive capability, and the preparation technology of catalyst layer 10 can be simplified, and then electrode performance and the result of use of this air cathode can be improved.
In addition, according to embodiments of the invention, with reference to figure 2, this air cathode can also have current collection layer 30 further.According to embodiments of the invention, current collection layer 30 can be formed by stainless steel, and such as, current collection layer 30 can be 50 object stainless (steel) wires.Thus, the current collection layer 30 that can consist of stainless steel has the current collection layer of good conductive ability for this air cathode improves, and then can improve the conductive capability of this air cathode further.It should be noted that, the concrete relative position of current collection layer 30, catalyst layer 10 and diffusion layer 20 is not particularly limited, as long as above-mentioned each layer can be made to play respective function, and can realize the electrode function of this air cathode.Such as, according to embodiments of the invention, this air cathode can have following structure: diffusion layer 20 contacts with air (not shown), current collection layer 30 is formed in the side of diffusion layer 20 away from air, catalyst layer 10 is formed in the side of current collection layer 30 away from diffusion layer 20, and with electrolyte contacts (not shown).Or, according to embodiments of the invention, with reference to figure 3, in this air cathode, diffusion layer 20 contacts with air (not shown), catalyst layer 10 is formed in the side (not shown) of diffusion layer 20 away from air, and current collection layer 30 is formed in the side of catalyst layer 10 away from diffusion layer 20, and with electrolyte contacts (not shown).In addition, current collection layer 30 can also be made to contact with air, form diffusion layer 20 in the side of current collection layer 30, at the side formation catalyst layer 10 of diffusion layer 20 away from current collection layer 30.Because current collection layer 30 can be formed by stainless (steel) wire, therefore current collection layer 30 contacts with air and also can realize the function that diffusion layer 20 promotes oxygen transmission.Thus, those skilled in the art according to the actual requirements, can select suitable Structure composing according to the air cathode of the embodiment of the present invention, and then can improve the result of use of this air cathode.
In addition, in order to improve the result of use of this air cathode further, this air cathode can also have supporting layer further.According to embodiments of the invention, with reference to figure 4, supporting layer 40 is formed between catalyst layer 10 and diffusion layer 20, and supporting layer 40 can be formed by stainless steel.In order to simplify the preparation process of this air cathode, supporting layer 40 can select to have 40 order stainless (steel) wires of the same area with current collection layer 30.Thus, can by supporting layer 40 for this air cathode provide better supporting construction, and supporting layer 40 and current collection layer 30 lay respectively at the both sides of catalyst layer 10, and then good protection can be provided for catalyst layer 10.In addition, the supporting layer 40 be made up of stainless (steel) wire can also improve the conductivity of this air cathode further, and then can improve the performance of this air cathode further.It should be noted that, under the prerequisite not paying creative work, also protection scope of the present invention is belonged to the improvement made according to the air cathode of the embodiment of the present invention.Such as, the structure that one deck is made up of stainless (steel) wire can be added again, to strengthen the electric conductivity of this air cathode and to provide better support to diffusion layer 20 at diffusion layer 20 away from the side of supporting layer 40.Thus, those skilled in the art can according to the actual requirements, selects suitable air cathode structure to form air cathode according to the embodiment of the present invention.
According to embodiments of the invention, catalyst layer 10 can obtain through the following steps:
Load nitrogen-doped graphene on the metallic substrate, to obtain catalyst layer 10.It should be noted that, the concrete composition of metallic substrates and shape are not particularly limited, as long as by nitrogen-doped graphene load in this metallic substrates, and directly can be applied in air cathode as catalyst layer.Such as, nickel screen or nickel foam can be selected as metallic substrates.Particularly, according to one embodiment of present invention, the quartz boat containing nickel screen can be placed in airtight reaction compartment, under 250 ~ 300 degrees Celsius, in reaction compartment, pass into inert gas, to discharge the air in described reaction compartment.It should be noted that, describing mode adopted in this article is " under 250 ~ 300 degrees Celsius, inert gas is passed in reaction compartment " should be interpreted broadly, heating reaction compartment and in reaction compartment, pass into inert gas is can be synchronous, successively or interval to carry out, namely first reaction compartment can be carried out heating and reach predetermined temperature, the i.e. temperature of 250 ~ 300 degrees Celsius, then in reaction compartment, inert gas is passed into, also inert gas can passed in the process heated reaction compartment in this reaction compartment, can also first inert gas be passed in reaction compartment, and then reaction compartment is heated, as long as finally realize at the temperature of 250 ~ 300 degrees Celsius, inert gas is there is in reaction compartment.
According to embodiments of the invention, the particular type of inert gas is not particularly limited, and those skilled in the art can select suitable inert gas according to actual needs, if this gas at high temperature not with any material generation chemical reaction in reaction compartment.Such as, according to embodiments of the invention, argon gas or nitrogen can be selected as inert gas, so that for providing inert atmosphere in reaction compartment.Temperature in reaction compartment is increased to 800 ~ 1200 degrees Celsius, and in reaction compartment, pass into hydrogen, the hydrogen passed into and the flow-rate ratio of inert gas are 1:40 ~ 1:1000 simultaneously.In addition, according to embodiments of the invention, can also before temperature in reaction compartment arrives predetermined temperature, increase the flow velocity of hydrogen and inert gas simultaneously, and then the effect of nickel screen surface being carried out to annealing in process can be reached, the nickel screen surface oxide layer that may exist is reduced, and then the performance of nitrogen-doped graphene of subsequent deposition can be improved.Liquid precursor is supplied in described reaction compartment.According to embodiments of the invention, the kind of liquid precursor is not particularly limited, as long as can provide carbon source and nitrogenous source for nitrogen-doped graphene, those skilled in the art can according to the actual requirements, select suitable liquid itrogenous organic substance matter as liquid precursor.According to a particular embodiment of the invention, this liquid precursor can be acetonitrile, pyridine and pyrroles.According to one embodiment of present invention, select acetonitrile as liquid precursor, the flow velocity of acetonitrile can be 2 ~ 1000 μ l/min, and service time can be 2 ~ 60 minutes.Thus, by the method for chemical vapour deposition (CVD), nickel screen directly can form nitrogen-doped graphene, and then obtain catalyst layer 10.
According to embodiments of the invention, diffusion layer 20 can be prepared by following steps: mixed with 60 quality % polytetrafluoroethylene (PTFE) dispersion liquids by carbon black, and the mass ratio of carbon black and 60 quality %PTFE dispersion liquids is 2:3.In the mixture of carbon black and 60 quality %PTFE dispersion liquids, add ethanol to increase the viscosity of said mixture, then, ultrasonic mixing 10-30 minute in the water-bath of 80 degrees Celsius, so that said mixture forms sticky mass.Finally, above-mentioned sticky mass is carried out forming processes, to obtain diffusion layer 20.Particularly, according to embodiments of the invention, by this sticky mass through kneading, 80 degrees Celsius, rub pressure fast under the pressure that is less than 0.5MPa, to make ethanol volatilize, and in the process of rubbing pressure, carbon black is combined with PTFE tightr.Repeat above-mentioned rubbing subsequently and press through journey 3-5 time, to improve diffusion layer 20 compressive property in use of preparation.Then, by the mixture through repeatedly rubbing pressure 80 degrees Celsius, under 1.5MPa by vertical compression machine vertical compression 10 seconds, to obtain sticky solid compressing tablet, adopt this sticky solid compressing tablet as diffusion layer 20.It should be noted that, according in the air cathode of the embodiment of the present invention, the catalyst layer 10 that this sticky solid compressing tablet directly and above can be obtained is by modes such as vertical compressions, catalyst layer 10 and diffusion layer 20 are fixed, and without the need to adhesive bond, thus production stage can be reduced, reduce preparation cost, reduce the consumption of binding agent, avoid binding agent to the negative effect of air cathode performance.
In sum, have less internal resistance according to the air cathode of the embodiment of the present invention, the air cathode according to the embodiment of the present invention (can be less than 2.5 μ g/cm having less catalyst layer load capacity
2) when, obtain good catalytic effect and power density.In addition, according to the air cathode of the embodiment of the present invention, also there is following characteristics and advantage:
1) adopt chemical vapour deposition technique to be directly deposited on nickel screen by nitrogen-doped graphene, the nitrogen-doped graphene obtained covering metal nickel screen and fault of construction is few equably, greatly can improve catalytic effect.
2) adopt nickel screen as nitrogen-doped graphene supporting substrate, microbiological fuel cell neutral environment can be applicable to, being that the load of catalyst provides high specific surface area improving while conductivity, promoting the catalytic performance of microbial fuel cell air cathode.
3) adopt nitrogen-doped graphene as the oxygen reduction catalyst of microbial fuel cell air cathode, the absorption of oxygen and the oxygen reduction reaction of electrode surface can be promoted, improve air cathode catalytic activity.
4) adopt the air cathode configuration of binder free supported catalyst, can significantly improve electrodes conduct performance, improve electron transfer efficiency, thus promote the power output of microbiological fuel cell.
5) the air cathode preparation technology of binder free supported catalyst is adopted, catalyst cupport method short, simple to operate and Catalytic Layer consuming time is easy to change, be applicable to large area to produce, greatly simplify air cathode preparation flow, contribute to microbiological fuel cell and promote the use of.
In another aspect of this invention, the present invention proposes a kind of method preparing air cathode.According to embodiments of the invention, the method comprises:
(1) catalyst layer is set
According to embodiments of the invention, in this step, nitrogen-doped graphene is loaded in metallic substrates, to obtain catalyst layer.It should be noted that, the concrete composition of metallic substrates and shape are not particularly limited, as long as by nitrogen-doped graphene load in this metallic substrates, and directly can be applied in air cathode as catalyst layer.Such as, nickel screen or nickel foam can be selected as metallic substrates.Particularly, according to one embodiment of present invention, the quartz boat containing nickel screen can be placed in airtight reaction compartment, under 250 ~ 300 degrees Celsius, in reaction compartment, pass into inert gas, to discharge the air in described reaction compartment.It should be noted that, describing mode adopted in this article is " under 250 ~ 300 degrees Celsius, inert gas is passed in reaction compartment " should be interpreted broadly, heating reaction compartment and in reaction compartment, pass into inert gas is can be synchronous, successively or interval to carry out, namely first reaction compartment can be carried out heating and reach predetermined temperature, the i.e. temperature of 250 ~ 300 degrees Celsius, then in reaction compartment, inert gas is passed into, also inert gas can passed in the process heated reaction compartment in this reaction compartment, can also first inert gas be passed in reaction compartment, and then reaction compartment is heated, as long as finally realize at the temperature of 250 ~ 300 degrees Celsius, inert gas is there is in reaction compartment.
According to embodiments of the invention, the particular type of inert gas is not particularly limited, and those skilled in the art can select suitable inert gas according to actual needs, if this gas at high temperature not with any material generation chemical reaction in reaction compartment.Such as, according to embodiments of the invention, argon gas or nitrogen can be selected as inert gas, so that for providing inert atmosphere in reaction compartment.Temperature in reaction compartment is increased to 800 ~ 1200 degrees Celsius, and in reaction compartment, pass into hydrogen, the hydrogen passed into and the flow-rate ratio of inert gas are 1:40 ~ 1:1000 simultaneously.In addition, according to embodiments of the invention, can also before temperature in reaction compartment arrives predetermined temperature, increase the flow velocity of hydrogen and inert gas simultaneously, and then the effect of nickel screen surface being carried out to annealing in process can be reached, the oxide layer that nickel screen surface may exist is reduced, and then the performance of subsequent deposition nitrogen-doped graphene can be improved.Liquid precursor is supplied in described reaction compartment.According to embodiments of the invention, the kind of liquid precursor is not particularly limited, as long as can provide carbon source and nitrogenous source for nitrogen-doped graphene, those skilled in the art can according to the actual requirements, select suitable liquid itrogenous organic substance matter as liquid precursor.According to a particular embodiment of the invention, this liquid precursor can be acetonitrile, pyridine and pyrroles.According to one embodiment of present invention, select acetonitrile as liquid precursor, the flow velocity of acetonitrile can be 2 ~ 1000 μ l/min, and service time can be 2 ~ 60 minutes.Thus, by the method for chemical vapour deposition (CVD), nickel screen directly can form nitrogen-doped graphene, and then obtain catalyst layer.
(2) diffusion layer is set
According to embodiments of the invention, in this step, first mixed with 60 quality % polytetrafluoroethylene (PTFE) dispersion liquids by carbon black, the mass ratio of carbon black and 60 quality %PTFE dispersion liquids is 2:3.In the mixture of carbon black and 60 quality %PTFE dispersion liquids, add ethanol to increase the viscosity of said mixture, then, ultrasonic mixing 10-30 minute in the water-bath of 80 degrees Celsius, so that said mixture forms sticky mass.Finally, above-mentioned sticky mass is carried out forming processes, to obtain diffusion layer 20.Particularly, according to embodiments of the invention, by this sticky mass through kneading, 80 degrees Celsius, rub pressure fast under the pressure that is less than 0.5MPa, to make ethanol volatilize, and in the process of rubbing pressure, carbon black is combined with PTFE tightr.Repeat above-mentioned rubbing subsequently and press through journey 3-5 time, to improve the diffusion layer compressive property in use of preparation.Then, by the mixture through repeatedly rubbing pressure 80 degrees Celsius, under 1.5MPa by vertical compression machine vertical compression 10 seconds, to obtain sticky solid compressing tablet, adopt this sticky solid compressing tablet as diffusion layer.Then, diffusion layer is placed on catalyst layer, by modes such as vertical compressions, catalyst layer 10 and diffusion layer 20 is fixed, to obtain air cathode.Thus, air cathode can be obtained easily, and utilize the method to prepare in the process of air cathode, not need to adopt binding agent various piece to be glued together, and then the electrode conductivuty of this air cathode can be improved, and simplify electrode preparation process.
In addition, according to embodiments of the invention, before diffusion layer is set, first current collection layer can be set.Particularly, current collection layer is formed by stainless steel, and current collection layer is arranged between diffusion layer and catalyst layer, or catalyst layer and diffusion layer are arranged on the same side of current collection layer.Such as, according to some embodiments of the present invention, current collection layer can be 50 object stainless (steel) wires.The diffusion layer sticky solid compressing tablet prepared directly is placed on 50 object stainless (steel) wires, 80 degrees Celsius, roll 1min, diffusion layer and current collection layer to be combined under the condition of 4.5MPa.The diffusion layer rolled and current collection layer are put into Muffle furnace, makes its curing molding at 340 degrees Celsius of lower heat treatment 15-20 minute.Subsequently, catalyst layer and the diffusion layer be combined and current collection layer can be put according to the position relationship between three layers, then direct catalyst layer, the diffusion layer combined in advance and current collection layer to be fixed by modes such as vertical compressions, and then the air cathode according to the embodiment of the present invention can be obtained.Thus, utilize the method to prepare in the process of air cathode, do not need to adopt binding agent various piece to be glued together, and then the electrode conductivuty of this air cathode can be improved, and simplify electrode preparation process.
According to embodiments of the invention, in the method, supporting layer can also be set further.Particularly, supporting layer is formed by stainless steel, and supporting layer is arranged between diffusion layer and catalyst layer.According to embodiments of the invention, in order to simplify the method preparing air cathode further, supporting layer can select to have stainless (steel) wire of the same area with current collection layer.It should be noted that, in the method, the particular location between each layer of air cathode is not particularly limited, as long as can realize the function of each layer in this air cathode, those skilled in the art can according to the actual requirements, be arranged the relative position between each layer.Such as, according to embodiments of the invention, can after diffusion layer and current collection layer be combined, supporting layer, catalyst layer, the diffusion layer be combined in advance and current collection layer are put according to the position in Fig. 4, then to be directly fixed by modes such as vertical compressions, and then the air cathode according to the embodiment of the present invention can be obtained.Thus, utilize the method to prepare in the process of air cathode, do not need to adopt binding agent various piece to be glued together, and then the electrode conductivuty of this air cathode can be improved, and simplify electrode preparation process.
Thus, the method can be utilized to obtain air cathode easily, and without the need to adopting binding agent to bond between each layer of this air cathode, therefore not only simplify the preparation process of air cathode, it also avoid the impact of binding agent for air cathode electric conductivity.In addition, be formed directly into nitrogen-doped graphene on nickel screen as catalyst layer owing to have employed in this air cathode, the air cathode therefore utilizing the method to prepare has feature and the advantage of previously described air cathode, does not repeat them here.
In still another aspect of the invention, the present invention proposes a kind of microbiological fuel cell.According to embodiments of the invention, with reference to figure 5, this fuel cell comprises: housing 100, anode 200, negative electrode 300 and electrogenesis microbe 400.Particularly, limit reaction compartment in housing 100, anode 200 and negative electrode 300 are arranged in reaction compartment, and electrogenesis microbe 500 is attached to the outer surface of anode 300.Negative electrode 400 is the previously described air cathode according to the embodiment of the present invention, and negative electrode 400 is arranged in reaction compartment, is electrically connected with anode 300.Thus, can be decomposed by the oxidation operation in medium by electrogenesis microbe 500, and produce electronics and proton, and accept electronics by negative electrode 400, catalytic oxidation-reduction reacts and generates water.Thus, the performance of this microbiological fuel cell can be improved.
Wherein, according to embodiments of the invention, anode 300 can be one of at least being formed of carbon brush, carbon cloth, carbon cloth and granular activated carbon.Particularly, anode 300 can for be cut into suitable size by carbon cloth or carbon brush, and 450 degrees Celsius of lower heat treatments obtain for 30 minutes in Muffle furnace.Thus, anode 300 can be obtained easily, and then reduce the production cost of this microbiological fuel cell.
In addition, it will be appreciated by those skilled in the art that under the prerequisite not paying creative work, also protection scope of the present invention is belonged to the improvement carried out according to the microbiological fuel cell of the embodiment of the present invention.Such as, according to one embodiment of present invention, anode 300 and negative electrode 400 can orthogonally be arranged; According to another embodiment of the invention, between negative electrode 400 and anode 300, barrier material can also be had further.Thus, those skilled in the art can according to actual conditions, make corresponding adjustment to according to the microbiological fuel cell of the embodiment of the present invention, select more suitable structure to form microbiological fuel cell, as long as meet the previously described feature according to the embodiment of the present invention.
Because this microbiological fuel cell have employed the negative electrode of previously described air cathode as battery, therefore this microbiological fuel cell has whole feature and the advantage of previously described air cathode, does not repeat them here.
In still another aspect of the invention, the present invention proposes the application of previously described microbiological fuel cell in process aqueous medium.Thus, the result of use of this fuel cell can be improved.It should be noted that, in the present invention, " process aqueous medium " is by being realized by the electrolyte of aqueous medium as microbiological fuel cell.Thus, can using according to the air cathode of the embodiment of the present invention as the negative electrode in microbiological fuel cell, and for the treatment of sewage, desalination, pollution amelioration and prepare sensor.In the present invention, term " aqueous medium " can be sewage, salting liquid, cushioning liquid or microbiological culture media etc.
Below by specific embodiment, the present invention will be described, it should be noted that, specific embodiment is below only used for the object illustrated, and the scope do not limited the present invention in any way, in addition, if no special instructions, then the method specifically not recording condition or step is conventional method, and the reagent adopted and material all can obtain from commercial channels.X-ray photoelectron power spectrum (XPS) adopts ThermoESCALAB250spectrometer to obtain.
Embodiment 1: Kaolinite Preparation of Catalyst layer
40 order nickel screens are cut into the rectangle of 4cm × 8cm, put into distilled water ultrasonic cleaning 5-10 minute, remove the impurity such as the dust on nickel screen surface.By cleaning after nickel screen be curled into the shape can putting into quartz boat, ensure nickel screen contactless each other, thus can with reacting gas good contact.Be placed on by nickel screen on quartz boat, quartz boat is connected with a copper wire, is wound around iron wire, quartz boat is slowly pushed into the middle part of reative cell at copper wire end.Ensure that iron wire part stays reative cell outside.In winding heating tape, preheating zone, design temperature is 270 degrees Celsius.Check the air-tightness of reaction unit, if air-tightness is good, then pass into the argon gas of 300mL/min, the air in discharger.Reative cell furnace temperature is set as 1000 degrees Celsius, and the heating-up time is 100min, heats up and in reative cell, passes into the argon gas of 300mL/min and the hydrogen of 20mL/min simultaneously.Before reative cell reaches design temperature during 30min, adjustment argon flow amount is 1000mL/min, and hydrogen flowing quantity is 50mL/min, carries out annealing in process to nickel screen, and the oxide layer of reduced nickel net surface reaches the effect of uniform crystal particles simultaneously.After reaching design temperature, keep furnace temperature and gas flow constant, with feed pump by acetonitrile with the feed rate of 20 μ L/min to entering in reative cell, the feeding time is 20min.After feeding terminates, close feed pump.Rapidly quartz boat is drawn in room temperature from high-temperature region with magnet, nickel screen is cooled fast.Gas flow is adjusted to argon gas 300mL/min, hydrogen 20mL/min simultaneously.Treat that furnace temperature is cooled to less than 200 degrees Celsius, open quartz ampoule, take out sample.
Embodiment 2: Kaolinite Preparation of Catalyst layer
Reference example 1, difference is, the sample rate of acetonitrile is 10 μ L/min, and sample injection time is 5 minutes.
Embodiment 3: Kaolinite Preparation of Catalyst layer
Reference example 1, difference is, the sample rate of acetonitrile is 20 μ L/min, and sample injection time is 5 minutes.
Embodiment 4: Kaolinite Preparation of Catalyst layer
Reference example 1, difference is, the sample rate of acetonitrile is 30 μ L/min, and sample injection time is 5 minutes.
Embodiment 5: Kaolinite Preparation of Catalyst layer
Reference example 1, difference is, the sample rate of acetonitrile is 50 μ L/min, and sample injection time is 5 minutes.
Embodiment 6: Kaolinite Preparation of Catalyst layer
Reference example 1, difference is, the sample rate of acetonitrile is 20 μ L/min, and sample injection time is 10 minutes.
Embodiment 7: Kaolinite Preparation of Catalyst layer
Reference example 1, difference is, the sample rate of acetonitrile is 20 μ L/min, and sample injection time is 15 minutes.
Fig. 6 and Fig. 7 is the scanning electron microscope (SEM) photograph (Fig. 6 b, Fig. 6 e, Fig. 7 b, Fig. 7 e are the catalyst layer stereoscan photograph of preparation in embodiment 3) of the catalyst layer of preparation in embodiment 1 ~ 7 under different resolution.With reference to figure 6 (a-d) and Fig. 7 (a-d) (being respectively the stereoscan photograph of the catalyst layer prepared in embodiment 2 ~ 5 under different resolution) when sample injection time is 5 minutes, contrast different acetonitrile sample rates, along with the lifting of sample rate, nitrogen-doped graphene surface folding increases, there is granule aggregate, therefore, when sample rate increases, the content of defect and impurity in the nitrogen-doped graphene prepared can be caused to increase.With reference to figure 6 (e-h) and Fig. 7 (e-h) (being respectively the stereoscan photograph of the catalyst layer prepared in embodiment 1,3,6 and 7 under different resolution), when sample rate is 20 μ L/min, contrast different acetonitrile sample injection times, along with sample injection time extends, nitrogen-doped graphene thickness is thickening.
With reference to figure 8 (A), contrast different acetonitrile sample rates, the nitrogen-doped graphene adopting the feed rate of 20 μ L/min to obtain shows best graphene-structured in Raman spectrum, does not namely occur being positioned at 1300cm
-1the D peak of defect content in the representative graphene-structured of left and right, with reference to figure 8 (B), the 2D peak of the nitrogen-doped graphene of all sample rates and the ratio at G peak are all between 0.25 to 0.35, and representing nitrogen-doped graphene structure is sandwich construction.In addition, with reference to figure 8, the test of x-ray photoelectron power spectrum has been carried out to the nitrogen-doped graphene obtained in embodiment 1.Particularly, Fig. 9 (a) for nitrogen-doped graphene photoelectron spectroscopy figure, Fig. 9 (b) be that N1s is meticulous can spectrogram.With reference to figure 9 (b), above-mentioned nitrogen-atoms exists with graphite nitrogen, pyrroles's nitrogen and pyridine nitrogen in this nitrogen-doped graphene, is conducive to above-mentioned three types nitrogen element strengthens this nitrogen-doped carbon oxygen reduction catalytic activity by synergy.
Embodiment 8: prepare air cathode
First, diffusion layer is prepared.On diffusion layer, the mass ratio of carbon black and PTFE controls at 2:3, and namely the load capacity of carbon black is about 25mg/cm
2, and the load capacity of PTFE is about 37.5mg/cm
2, according to 11.3cm
2size take carbon black and PTFE, add ethanol in proper amount, increase mixture viscosity.Ultrasonic mixing 10-30min in the water-bath of 80 degrees Celsius is until form sticky mass.Sticky mass through kneading, 80 degrees Celsius, rub pressure fast under the pressure that is less than 0.5MPa, repeatedly integrate compacting with condition of similarity subsequently and integrate 3-5 time again, at 80 degrees Celsius, vertical compression 10s under 1.5MPa.Sticky solid after the compacting obtained is placed on 50 object stainless (steel) wires (as current collection layer), at 80 degrees Celsius, pressurize 1min under the condition of 4.5MPa.The diffusion layer rolled and current collection layer are put into Muffle furnace, makes its curing molding at 340 degrees Celsius of heat treatment 15-20min.Get 50 object stainless (steel) wires again as supporting layer, by the Catalytic Layer of preparation in embodiment 1, be clipped between current collection layer and supporting layer, directly put into reactor and press to together.Each layer relative position reference Fig. 4.
Embodiment 9: prepare air cathode
Reference example 8, difference is to prepare in the process of diffusion layer, is directly placed on the nickel screen of load nitrogen-doped graphene by the sticky solid after compacting, with at 80 degrees Celsius, pressurize 1min under the condition of 3MPa.Directly using nickel screen as current collection layer and supporting layer, using suppressing of obtaining, the nickel screen of diffusion layer is as air cathode, each interlayer relative position reference Fig. 1.
Embodiment 10: prepare air cathode
Reference example 8, difference is to prepare in the process of air cathode, and by load, the nickel screen of nitrogen-doped graphene is compressed together with the stainless (steel) wire having suppressed diffusion layer, and wherein nickel screen is towards diffusion layer side, stainless (steel) wire is towards air side.
Embodiment 11: prepare microbiological fuel cell
Adopt the air cathode of preparation in embodiment 8 as negative electrode.
Prepare anode: adopt carbon brush, carbon cloth, carbon cloth or granular activated carbon etc. as the attachment of anode and electrogenesis bacterium, carbon brush or carbon cloth or carbon cloth 450 degrees Celsius of lower heat treatment 30min in Muffle furnace.
By above-mentioned anode, air cathode composition single chamber type microbiological fuel cell, inoculation runs the electrogenesis bacterium of more than 1 year continuously, connects external circuit, test single chamber type microbiological fuel cell performance.The electrolyte adopted is neutral phosphate buffer, wherein contains the sodium acetate of 1g/L as substrate, the mineral matter of 12.5mL/L and the vitamin supplement nutriment of 5mL/L.
Comparative example 1:
Comparative example 1 has prepared widely used platinum carbon air cathode (Pt) in microbiological fuel cell.Wherein, the platinum carbon dust (C1-1010%wt.PtonCarbonBlackVulcanXC-72R, BASFFuelCellInc, the U.S.) of the catalyst of Pt negative electrode to be platinum containing amount be 10 quality %, platinum carbon dust load capacity is 5mg/cm
2.Particularly, Pt cathode preparation method is as follows:
(1) carbon based layer is coated with.Being cut out by carbon cloth is the rectangle of 4 × 8cm.Weigh 50mg carbon black powders, load in 10mL centrifuge tube, add 600 μ L40 quality %PTFE solution, then add 6 ~ 8 beades, use oscillator vibrates even, about 20 seconds.With paintbrush brush, molten for carbon black slurry is applied on carbon cloth.After being coated with, natural air drying at least two hours under air.Afterwards carbon cloth is placed in temperature constant and heats about 25 minutes at the Muffle furnace of 370 degrees Celsius, taking-up after heat treatment completes, is cooled to room temperature.
(2) diffusion layer is coated with.With paintbrush brush by 60 quality %PTFE solution coat on the carbon cloth being coated with carbon based layer side, air-dry about 10 minutes under air, until PTFE layer become completely white.Be put into by carbon cloth in the Muffle furnace of the constant temperature of 370 degrees Celsius, heat about 12 minutes, PTFE layer is solidified, has heated rear taking-up, be cooled to room temperature, PTFE layer becomes canescence.Repeat above step, be painted with till 4 layers until PTFE layer.With mould and hammer, carbon cloth is processed into the circle that two panels diameter is 3.8cm.
(3) coating catalytic layer.Each negative electrode takes the platinum carbon dust (C1-1010%wt.PtonCarbonBlackVulcanXC-72R that 60mg platinum containing amount is 10 quality %, BASFFuelCellInc, the U.S.), put into 10mL centrifuge tube, add deionized water and 6 ~ 8 beades of 50 μ L, oscillator vibrates is about 20s.Add 400 μ LNafion solution and 200 μ L high-purity isopropanols again, oscillator vibrates is about 20s.In carbon cloth, do not contain the side of carbon based layer and diffusion layer by paintbrush brushing cloth Catalytic Layer, be coated with rear natural air drying at least 24 hours.
Electrochemical half-cell is tested
Below the chemical property of negative electrode prepared by above-described embodiment is tested.Adopt the catalyst layer of preparation in embodiment 1 ~ 7, prepare air cathode according to the method for embodiment 8.Reactor is double chamber type reactor, and two body cavity are separated by anion-exchange membrane; Be platinum plate electrode to electrode, reference electrode is saturated calomel reference electrode, and work electrode is air cathode to be determined or platinum carbon cathode.Negative electrode is fixed by O type ring, and diffusion layer side exposes in atmosphere.Titanium sheet is adopted to draw electric material as negative electrode.Electrolyte is the PBS of 50mM.The formula of the phosphate buffer solution of 50mM is as shown in the table.
Table 150mM PBS
| Material | Concentration |
| Sodium hydrogen phosphate (Na 2HPO 4) | 4.57g/L |
| One hypophosphite monohydrate sodium dihydrogen (NaH 2PO 4·H 2O) | 2.45g/L |
| Ammonium chloride (NH 4Cl) | 0.31g/L |
| Potassium chloride (KCl) | 0.13g/L |
Linear sweep voltammetry target performance is adopted to evaluate, open a way after 3 hours, from onset potential 0V (reference electrode is saturated calomel) measure, destination potential Wei – 0.4V (reference electrode is saturated calomel electrode), with active cathodic area 7cm
2conversion is current density.With reference to Figure 10, under – 0.3V to – 0.4V same potential, in embodiment 1,20 μ L/min solution feed rates obtain maximum current density, and along with the solution feeding time increases, current density increases gradually.
Microbiological fuel cell is tested
Performance test is carried out below to according to the microbiological fuel cell prepared in the microbiological fuel cell of the embodiment of the present invention and above-mentioned comparative example.This microbiological fuel cell is single chamber type reactor, and without barrier film, anode is carbon brush, and be made up of carbon fiber wire and titanium silk, wherein titanium silk is as current-collecting member, through 450 degrees Celsius of heat treatments in 30 minutes.Anode is placed horizontally in the middle part of reactor, negative electrode place with reactor side, diffusion layer towards and be exposed to air.Employing Mixed Microbes is inoculated, and inoculation source is the air type microbiological fuel cell water outlet of operation more than 1 year, and initial inoculation source takes from the sanitary sewage of sewage treatment plant's primary sedimentation pond.Matrix is neutral 50mM phosphate buffer, wherein contain the sodium acetate of 1g/L as substrate, the mineral matter of 12.5mL/L and the vitamin supplement nutriment of 5mL/L, and the chemical oxygen demand of this matrix (COD) is 780mg/L.
Adopt and change extrernal resistance method mensuration polarization curve, calculate the power density of microbiological fuel cell.Reactor progressively successively decreases from 1000 Ω and moves to 20 Ω, under each resistance, runs complete cycle.
First, with reference to Figure 11 (a), adopt the catalyst layer of preparation in embodiment 2 ~ 5, and prepare air cathode according to the method in embodiment 2.With reference to Figure 11 (a), when sample rate is 20 μ L/min, the largest face power density suitable with the platinum carbon air cathode numerical value prepared in comparative example 1 can be obtained, simultaneously with reference to Figure 12 (a) and Figure 13 (a), when sample rate is 20 μ L/min, obtain maximum cathode potential, with minimum negative electrode internal resistance.But according to the air cathode of the embodiment of the present invention owing to having extremely low catalyst loadings, and not containing noble metals such as platinum in catalyst layer, therefore cost will well below platinum carbon air cathode.
Adopt the catalyst layer of preparation in embodiment 1,3,6,7, and obtain air cathode according to the method in embodiment 8.With reference to Figure 11 (b), the air cathode that each sample injection time obtains all obtains the surface power density higher than comparative example 1.Simultaneously with reference to Figure 12 (b) and Figure 13 (b), along with the growth of sample injection time, the air cathode electromotive force of acquisition improves gradually, and negative electrode internal resistance reduces gradually, is all less than the negative electrode internal resistance in comparative example 1.
In the description of this specification, specific features, structure, material or feature that the description of reference term " embodiment ", " some embodiments ", " example ", " concrete example " or " some examples " etc. means to describe in conjunction with this embodiment or example are contained at least one embodiment of the present invention or example.In this manual, to the schematic representation of above-mentioned term not must for be identical embodiment or example.And the specific features of description, structure, material or feature can combine in one or more embodiment in office or example in an appropriate manner.In addition, when not conflicting, the feature of the different embodiment described in this specification or example and different embodiment or example can carry out combining and combining by those skilled in the art.
Although illustrate and describe embodiments of the invention above, be understandable that, above-described embodiment is exemplary, can not be interpreted as limitation of the present invention, and those of ordinary skill in the art can change above-described embodiment within the scope of the invention, revises, replace and modification.
Claims (10)
1. an air cathode, is characterized in that, comprising:
Catalyst layer, described catalyst layer contains nitrogen-doped graphene; And
Diffusion layer.
2. air cathode according to claim 1, is characterized in that, comprises further:
Current collection layer, wherein,
Described current collection layer is formed by stainless steel, and described current collection layer is arranged between described diffusion layer and described catalyst layer, or
Described catalyst layer and described diffusion layer are arranged on the same side of described current collection layer.
3. air cathode according to claim 2, is characterized in that, comprises further:
Supporting layer, described supporting layer is arranged between described diffusion layer and described catalyst layer, and described supporting layer is formed by stainless steel,
Optionally, described catalyst layer is formed in the side of described current collection layer, and described supporting layer is formed in the side of described catalyst layer away from described current collection layer, and described diffusion layer is formed in the side of described supporting layer away from described catalyst layer.
4. air cathode according to claim 1, is characterized in that, not containing binding agent in described catalyst layer,
Optionally, in described catalyst layer, the load capacity of described nitrogen-doped graphene is not more than 2.5 μ g/cm
2,
Optionally, described catalyst layer comprises metallic substrates and described nitrogen-doped graphene, and described nitrogen-doped graphene load is in described metallic substrates.
5. air cathode according to claim 4, is characterized in that, described catalyst layer is formed through the following steps:
Quartz boat containing described metallic substrates is placed in airtight reaction compartment, wherein, described metallic substrates comprise nickel screen and nickel foam one of at least;
Under 250 ~ 300 degrees Celsius, in described reaction compartment, pass into inert gas, to discharge the air in described reaction compartment;
Temperature in described reaction compartment is increased to 800 ~ 1200 degrees Celsius, and in described reaction compartment, pass into hydrogen, the flow-rate ratio of described hydrogen and described inert gas is 1:40 ~ 1:1000 simultaneously; And
Liquid precursor is supplied in described reaction compartment, described liquid precursor comprise be selected from acetonitrile, pyridine and pyrroles one of at least, the flow velocity of described liquid precursor is 2 ~ 1000 μ l/min, the service time of described liquid precursor is 2 ~ 60 minutes, so that nitrogen-doped graphene described in load in described metallic substrates, and then obtain described catalyst layer.
6. prepare a method for air cathode, it is characterized in that, comprising:
(1) load nitrogen-doped graphene on the metallic substrate, to obtain catalyst layer; And
(2) diffusion layer is set in the side of described catalyst layer, to obtain described air cathode.
7. method according to claim 6, is characterized in that, described catalyst layer is formed by following steps:
Quartz boat containing described metallic substrates is placed in airtight reaction compartment, wherein, described metallic substrates comprise nickel screen and nickel foam one of at least; Under 250 ~ 300 degrees Celsius, in described reaction compartment, pass into inert gas, to discharge the air in described reaction compartment; Temperature in described reaction compartment is increased to 800 ~ 1200 degrees Celsius, and in described reaction compartment, pass into hydrogen, the flow-rate ratio of described hydrogen and described inert gas is 1:40 ~ 1:1000 simultaneously; And liquid precursor is supplied in described reaction compartment, described liquid precursor comprise be selected from acetonitrile, pyridine and pyrroles one of at least, the flow velocity of described liquid precursor is 2 ~ 1000 μ l/min, the service time of described liquid precursor is 2 ~ 60 minutes, so that nitrogen-doped graphene described in load in described metallic substrates, and then obtain described catalyst layer
Described diffusion layer is formed by following steps: get carbon black and teflon mixture that mass ratio is 2:3, add ethanol and in 80 C water bath ultrasonic 10 ~ 30 minutes to forming mixture of viscous form; Described mixture of viscous form is carried out forming processes, to obtain described diffusion layer.
8. method according to claim 6, it is characterized in that, before described diffusion layer is set, pre-set current collection layer, described current collection layer is formed by stainless steel, and wherein, described current collection layer is arranged between described diffusion layer and described catalyst layer, or described catalyst layer and described diffusion layer are arranged on the same side of described current collection layer
Optionally, described method comprises further: arrange supporting layer, and described supporting layer is arranged between described diffusion layer and described catalyst layer, and described supporting layer is formed by stainless steel.
9. a microbiological fuel cell, is characterized in that, comprising:
Housing, limits reaction compartment in described housing;
Anode, described anode is arranged in described reaction compartment;
Electrogenesis microbe, described electrogenesis microbial adhesion is at the outer surface of described anode; And
Air cathode described in any one of Claims 1 to 5, described air cathode is arranged in described reaction compartment, and described air cathode is electrically connected with described anode.
10. the purposes of microbiological fuel cell according to claim 9 in process aqueous medium.
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