CN111724995A - Manganese cobalt spinel sulfide composite counter electrode of quantum dot sensitized solar cell - Google Patents

Manganese cobalt spinel sulfide composite counter electrode of quantum dot sensitized solar cell Download PDF

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CN111724995A
CN111724995A CN201910213260.XA CN201910213260A CN111724995A CN 111724995 A CN111724995 A CN 111724995A CN 201910213260 A CN201910213260 A CN 201910213260A CN 111724995 A CN111724995 A CN 111724995A
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counter electrode
electrode
cnts
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ethanol
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何磊
张静
李彬
李文化
陈迁乔
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Nanjing University of Science and Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/20—Light-sensitive devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/04—Electrodes or formation of dielectric layers thereon
    • H01G9/042—Electrodes or formation of dielectric layers thereon characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/20—Light-sensitive devices
    • H01G9/2022—Light-sensitive devices characterized by he counter electrode
    • 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
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/542—Dye sensitized solar cells

Abstract

The invention provides a manganese cobalt spinel sulfide composite counter electrode of a quantum dot sensitized solar cell. The invention adopts a two-step method of depositing a precursor on a carbon nano tube and exchanging anions to prepare nano spinel MnCo2S4And CNTs composites, and is used for a counter electrode of a quantum dot sensitized solar cell. MnCo used in the counter electrode of the present invention2S4Has electrocatalytic activity, and when CNTs are added as precursor crystal nuclei, MnCo2S4the/CNTs show the best electrocatalytic properties, so the invention integrates the ternary spinel MnCo2S4Good electrocatalytic activity and higher electrical conductivity of the CNTs.

Description

Manganese cobalt spinel sulfide composite counter electrode of quantum dot sensitized solar cell
Technical Field
The invention belongs to the technical field of quantum dot sensitized solar cells, and particularly relates to a manganese cobalt spinel sulfide composite counter electrode of a quantum dot sensitized solar cell.
Background
The ever-worsening energy consumption and increasing global environmental issues have greatly stimulated global research interest in inexpensive renewable energy sources. On the basis of the third generation solar cell represented by the dye-sensitized solar cell, a Quantum Dot Sensitized Solar Cell (QDSSCs) has been developed. As the QDSSCs theory has the photoelectric conversion efficiency as high as 44%, the limit (31%) of Shockley-Queisser is broken through, and the QDSSCs theory is widely concerned by researchers.
The QDSSCs comprise a counter electrode, an electrolyte and a photo-anode, wherein the counter electrode is used for collecting electrons of an external circuit and reducing and regenerating the electrolyte, and plays a vital role in improving the photoelectric efficiency of the cell. When the conventional platinum and other noble metals are used as counter electrodes, the platinum electrode is easily poisoned by polysulfide electrolyte, so that the performance of the platinum electrode is reduced. Therefore, a great deal of research work has been conducted to explore how to obtain a counter electrode (electrocatalyst) having high catalytic activity and low cost in a quantum dot sensitized solar cell. The results of the study show that many transition metal sulfides include Cu2S、CuS、PbS、CoS、NiS、CuInS2、Co3S4When the catalyst is used as a counter electrode material of the QDSSCs battery, the catalyst shows better catalytic activity, and the open-circuit voltage and the short-circuit current of the corresponding battery are obviously improved compared with Pt. And ternary spinel type metal sulfides (AB)2S4) Because of their outstanding chemical and physical properties, they are widely used as important functional materials.
Zhang et al by sulfurizing MnCo2O4Preparation of spinel-structured MnCo directly grown on Ti network from nanowire array precursor2S4Nanowire arrays (MnCo)2S4NA/TM) for an electrocatalyst for efficient oxygen evolution reaction under alkaline conditions. Zoya Sadighi et al prepared mesoporous MnCo grown on carbon paper by electrodeposition and then low temperature sulfidation2S4Nanosheet array and first application to Li-O2An efficient catalyst for the cell, having high conductivity. Yu et al use hydrothermal treatment and electrochemical deposition to deposit a bilayer of MnCo2S4@ Ni-Co-S (MCS @ NCS) core/shell nanocomposites were successfully deposited onOn nickel foam, MnCo2S4Nanorods and MnCo2O4The nano-rod has larger specific surface area compared with the nano-rod, and shows good cycling stability when being used for a high-performance super capacitor. The application of Mn-Co spinel sulphides to the counter electrode of QDSSCs is not mentioned in previous reports, and the reported electrochemical performance of Mn-Co spinel sulphides is not particularly high.
Disclosure of Invention
The invention aims to provide a manganese cobalt spinel sulfide counter electrode of a quantum dot sensitized solar cell with excellent electrocatalytic activity and a manufacturing method thereof.
The technical scheme for realizing the purpose of the invention is as follows:
a manganese cobalt spinel sulfide composite counter electrode of a quantum dot sensitized solar cell is prepared by the following specific preparation steps:
1) and (3) purifying the carbon nano tube: adding carbon nano tubes into a mixture of nitric acid and sulfuric acid, stirring, heating and refluxing; cooling to room temperature, washing the carbon nanotubes with distilled water and absolute ethyl alcohol alternately to neutrality, and drying the collected matter for further use;
2) preparation of Mn-Co/CNTs precursor: putting the purified carbon nano tube obtained in the step 1) into ethanol for ultrasonic dispersion, and then adding Mn (OAc)2·4H2O、Co(OAc)2·4H2O and urea, fully stirring, and heating and refluxing; after the temperature is reduced to normal temperature, centrifugally washing the product by using ethanol for three times, collecting the product, and finally drying the product in a vacuum drying oven at 50 ℃ for 12 hours;
3)MnCo2S4preparation of/CNTs: dissolving the precursor obtained in the step 2) and thioacetamide in ethanol, performing magnetic stirring, and transferring the solution to a hydrothermal kettle for reaction; after the reaction is finished, centrifugally washing the reaction product for multiple times by using deionized water and ethanol, and finally drying the reaction product in a vacuum drying oven at 50 ℃ for more than 12 hours;
4) assembling the electrodes: uniformly dripping the sample obtained in the step 3) on a conductive substrate at the solubility of 5mg/ml ethanol, and heating and drying to obtain a counter electrode; then, scraping the counter electrode into a square active area, and sticking packaging glue on the left, right and lower three sides of the square active area; and finally assembling the paired electrodes.
Further, in the step 1), the carbon nanotubes are industrial multi-wall carbon nanotubes or single-wall carbon nanotubes; the volume ratio of the nitric acid to the sulfuric acid is 1: 3-1: 3.5; the heating reflux temperature is 80 ℃, and the time is 1-2 hours.
Further, in step 2), Mn (OAc) is added2·4H2O、Co(OAc)2·4H2The mass ratio of O to urea is 1:2.033: 2.412.
Further, in step 2), weighing CNTs and Mn (OAc)2·4H2The mass ratio of O is 1: 4.396.
Further, in step 2), weighing CNTs and Mn (OAc)2·4H2The mass ratio of O is 1: 3.297.
Further, in step 2), weighing CNTs and Mn (OAc)2·4H2The mass ratio of O is 1: 2.637.
Further, in the step 2), the heating reflux temperature is 85 ℃ and the time is 2-3 hours.
Further, in the step 3), the concentration contents of the precursor and thioacetamide in ethanol are respectively 2mg/ml and 3 mg/ml; stirring for 10-20 min; the hydrothermal reaction temperature is 110-130 ℃; the heat preservation time is 5-7 h.
Further, in the step 4), the conductive substrate is an FTO transparent conductive substrate or an ITO transparent conductive substrate, and the drying temperature is 50-80 ℃.
Compared with the prior art, the invention has the following advantages:
(1) counter electrode of the invention with MnCo alone2S4In contrast to CNTs, the composite counter electrode has a smaller charge transfer resistance (R)ct1.09 Ω), faster charge transfer rate, and greater exchange current density (J)0＝12.01mA·cm-2) And shows better electrocatalytic activity.
(2) The counter electrode of the invention is observed through SEM images, and MnCo is formed after the carbon nano tubes are compounded2S4Size ofObviously reduces the aggregation, improves the aggregation condition and increases the specific surface area. Thus, morphological advantages provide the possibility of increasing the electrocatalytic activity.
(3) The invention uses MnCo2S4CNTs composite counter electrode, polysulfide electrolyte and TiO2The assembly of the/CdS/CdSe photo-anode can obtain 4.85 percent photoelectric conversion efficiency which is respectively compared with MnCo2S4And CNTs are improved by 62.75 percent and 104.64 percent.
Drawings
FIG. 1 is MnCo2S4X-ray powder diffraction pattern of/CNTs composite material.
FIG. 2 is MnCo2S4CNTs composite and MnCo2S4Scanning electron micrograph (c).
FIG. 3 is MnCo2S4Electrochemical impedance spectrum of/CNTs composite counter electrode.
FIG. 4 is MnCo2S4Bode plot of/CNTs composite counter electrode.
FIG. 5 is MnCo2S4Tafel polarization curve diagram of/CNTs composite counter electrode.
FIG. 6 is based on MnCo2S4Graph of photocurrent density versus photovoltage for QDSSCs for a/CNTs composite counter electrode.
Detailed Description
The present invention will be described in more detail with reference to the following examples and the accompanying drawings.
Example 1
(I) MnCo2S4Preparation of/CNTs 15 composite counter electrode
1) Purification of carbon nanotubes
With HNO3And H2SO4，The volume ratio is 1: and 3, purifying the MWNTs. 1g of MWCNTs was added to 150mL of the acid mixture in a round bottom flask and refluxed at 80 ℃ for 1 h. After cooling, the mixture was washed with distilled water until near neutrality was obtained. The collection was then dried at 80 ℃ for 12h for further use.
2) Preparation of Mn-Co/CNTs precursor
Weighing 0096g of purified carbon nanotubes in 200ml of ethanol, followed by 0.422g of Mn (OAc)2·4H2O、0.858g Co(OAc)2·4H2O and 1.018g of urea, after stirring well, were warmed to 85 ℃ and refluxed at this temperature for 2 h. After cooling to normal temperature, the product is collected by centrifugal washing with ethanol three times, and finally dried in a vacuum drying oven at 50 ℃ for 12 h.
3)MnCo2S4Preparation of/CNTs
0.08g of the precursor and 0.12g of thioacetamide are weighed and added into 40ml of ethanol to be stirred for 10min, and then the solution is transferred into a hydrothermal reaction kettle to react for 6h at 120 ℃. After the reaction is finished, cooling to normal temperature, and centrifugally washing for many times by deionized water and ethanol. And finally drying in a vacuum drying oven at 50 ℃ for 12 h.
4) Preparation of counter electrode
And uniformly dripping the prepared sample on the FTO conductive glass surface cleaned in advance at the solubility of 5mg/ml ethanol, and heating and drying to obtain the counter electrode.
(di) TiO2Preparation of/CdS/CdSe/ZnS photo-anode
Coating the slurry of titanium dioxide on FTO conductive glass by a spin coating method, coating 6 layers, and calcining in a muffle furnace at 500 ℃ for 30 min. Three quantum dots were deposited using sequential ionic layer reactive adsorption (SILAR). First, TiO is mixed2Film immersion in 0.1MCd (CH)3COO)2Ethanol solution for 1min, and deionized water for cleaning excessive Cd on the surface2+Drying at 60 ℃; then, the TiO is mixed2Film immersion in 0.1M Na2And (3) carrying out cleaning and drying in the mixed solution of S methanol and water for 1min, thus finishing the deposition of the CdS quantum dots for 1 time. This process was repeated 5 times. The most difference between CdSe quantum dot deposition and CdS is that the deposition time is longer, and Na needs to be in an anion solution2SeSO3Soaking at 50 deg.c for 30min to deposit 8 layers of CdSe. And finally covering the surface with a ZnS passivation layer 2 by using an SILAR method.
Preparation of polysulfide electrolyte
Figure BDA0002001213860000041
Reference to The preparation of polysulfides (Soo-Yong Lee, Min-Ah Park, Jae-Hong Kim, et al, Journal of The Electrochemical Society,160(11), H847-H851,2013), mixing Na with sodium2S·9H2O (2M), S (2M) and KCl (0.2M) in 7ml methanol and 3ml H2And O, putting the mixture into a water bath at 50 ℃ and stirring for 1 h.
(IV) MnCo2S4Performance test of virtual symmetrical battery assembled by/CNTs composite counter electrode
Scraping the prepared counter electrode to 0.16cm2The active area of the electrode is increased, then three surfaces of the active coating are adhered with insulating adhesive tapes, then two counter electrodes are assembled into a symmetrical electrode with a sandwich structure, electrolyte is injected between the electrodes through an injector, and the time is waited for 5-10 min. The assembled symmetric electrode was tested for Electrochemical Impedance Spectroscopy (EIS), Bode plots (Bode plots), and Tafel polidationcurves (Tafel polistringcurves).
(V) counter electrode and TiO2QDSSCs (quantum dots for direct light scattering) testing photovoltaic performance assembled by/CdS/CdSe/ZnS photoanode
And assembling the prepared counter electrode and the photo-anode into a sandwich structure, dripping electrolyte, and waiting for 5-10 min. And carrying out a photocurrent density-photovoltage (J-V) test under standard sunlight to characterize the photovoltaic performance of the counter electrode.
Example 2
(I) MnCo2S4Preparation of/CNTs 20 composite counter electrode
1) Purification of carbon nanotubes
With HNO3And H2SO4(volume ratio 1: 3) MWNTs were purified. 1g of MWCNTs was added to 150mL of the acid mixture in a round bottom flask and refluxed at 80 ℃ for 1 h. After cooling, the mixture was washed with distilled water until near neutrality was obtained. The collection was then dried at 80 ℃ for 12h for further use.
2) Preparation of Mn-Co/CNTs precursor
0.128g of purified carbon nanotubes was weighed into 200ml of ethanol, and 0.422g of Mn (OAc) was added2·4H2O、0.858g Co(OAc)2·4H2O and 1.018g of urea, after stirring well, were warmed to 85 ℃ and refluxed at this temperature for 2 h. After cooling to normal temperature, the product is collected by centrifugal washing with ethanol three times, and finally dried in a vacuum drying oven at 50 ℃ for 12 h.
3)MnCo2S4Preparation of/CNTs
0.08g of the precursor and 0.12g of thioacetamide are weighed and added into 40ml of ethanol to be stirred for 10min, and then the solution is transferred into a hydrothermal reaction kettle to react for 6h at 120 ℃. After the reaction is finished, cooling to normal temperature, and centrifugally washing for many times by deionized water and ethanol. And finally drying in a vacuum drying oven at 50 ℃ for 12 h.
4) Preparation of counter electrode
And uniformly dripping the prepared sample on the FTO conductive glass surface cleaned in advance at the solubility of 5mg/ml ethanol, and heating and drying to obtain the counter electrode.
(di) TiO2Preparation of/CdS/CdSe/ZnS photo-anode
The preparation of photoanodes is referred to the literature (ChanduV.V.Muralee Gopi, Seenu Ravi, et al, Scientific Reports, volume 7, particle number:46519(2017)), with the difference that:
coating the slurry of titanium dioxide on FTO conductive glass by a spin coating method, coating 6 layers, and calcining in a muffle furnace at 500 ℃ for 30 min. Three quantum dots were deposited using sequential ionic layer reactive adsorption (SILAR). First, TiO is mixed2Film immersion in 0.1MCd (CH)3COO)2Ethanol solution for 1min, and deionized water for cleaning excessive Cd on the surface2+Drying at 60 ℃; then, the TiO is mixed2Film immersion in 0.1M Na2And (3) carrying out cleaning and drying in the mixed solution of S methanol and water for 1min, thus finishing the deposition of the CdS quantum dots for 1 time. This process was repeated 5 times. The most difference between CdSe quantum dot deposition and CdS is that the deposition time is longer, and Na needs to be in an anion solution2SeSO3Soaking at 50 deg.c for 30min to deposit 8 layers of CdSe. And finally covering the surface with a ZnS passivation layer 2 by using an SILAR method.
Preparation of polysulfide electrolyte
Figure BDA0002001213860000051
Reference to The preparation of polysulfides (Soo-Yong Lee, Min-Ah Park, Jae-Hong Kim, et al, Journal of The Electrochemical Society,160(11), H847-H851,2013), mixing Na with sodium2S·9H2O (2M), S (2M) and KCl (0.2M) in 7ml methanol and 3ml H2And O, putting the mixture into a water bath at 50 ℃ and stirring for 1 h.
(IV) MnCo2S4Testing the performance of a virtual symmetrical battery assembled by a/CNTs composite counter electrode, namely scraping the prepared counter electrode to 0.16cm2The active area of the electrode is increased, then three surfaces of the active coating are adhered with insulating adhesive tapes, then two counter electrodes are assembled into a symmetrical electrode with a sandwich structure, electrolyte is injected between the electrodes through an injector, and the time is waited for 5-10 min. The assembled symmetric electrode was tested for Electrochemical Impedance Spectroscopy (EIS), Bode plots (Bode plots), and Tafel polarization curves (Tafel polarization curves).
(V) counter electrode and TiO2QDSSCs (quantum dots for direct light scattering) testing photovoltaic performance assembled by/CdS/CdSe/ZnS photoanode
And assembling the prepared counter electrode and the photo-anode into a sandwich structure, dripping electrolyte, and waiting for 5-10 min. And carrying out a photocurrent density-photovoltage (J-V) test under standard sunlight to characterize the photovoltaic performance of the counter electrode.
Example 3
(I) MnCo2S4Preparation of/CNTs 25 composite counter electrode
1) Purification of carbon nanotubes
With HNO3And H2SO4(volume ratio 1: 3) MWNTs were purified. 1g of MWCNTs was added to 150mL of the acid mixture in a round bottom flask and refluxed at 80 ℃ for 1 h. After cooling, the mixture was washed with distilled water until near neutrality was obtained. The collection was then dried at 80 ℃ for 12h for further use.
2) Preparation of Mn-Co/CNTs precursor
0.160 g of purified carbon nanotubes was weighed into 200ml of ethanol, and 0.422g of Mn (OAc) was added2·4H2O、0.858g Co(OAc)2·4H2O and 1.018g of urea, after stirring well, were warmed to 85 ℃ and refluxed at this temperature for 2 h. After cooling to normal temperature, the product is collected by centrifugal washing with ethanol three times, and finally dried in a vacuum drying oven at 50 ℃ for 12 h.
3)MnCo2S4Preparation of/CNTs
0.08g of the precursor and 0.12g of thioacetamide are weighed and added into 40ml of ethanol to be stirred for 10min, and then the solution is transferred into a hydrothermal reaction kettle to react for 6h at 120 ℃. After the reaction is finished, cooling to normal temperature, and centrifugally washing for many times by deionized water and ethanol. And finally drying in a vacuum drying oven at 50 ℃ for 12 h.
4) Preparation of counter electrode
And uniformly dripping the prepared sample on the FTO conductive glass surface cleaned in advance at the solubility of 5mg/ml ethanol, and heating and drying to obtain the counter electrode.
(di) TiO2Preparation of/CdS/CdSe/ZnS photo-anode
The preparation of photoanodes is referred to the literature (Chandu V.V.Muralee Gopi, Seenu Ravi, et al, Scientific Reports, volume 7, particle number:46519(2017)), with the difference that:
coating the slurry of titanium dioxide on FTO conductive glass by a spin coating method, coating 6 layers, and calcining in a muffle furnace at 500 ℃ for 30 min. Three quantum dots were deposited using sequential ionic layer reactive adsorption (SILAR). First, TiO is mixed2Film immersion in 0.1MCd (CH)3COO)2Ethanol solution for 1min, and deionized water for cleaning excessive Cd on the surface2+Drying at 60 ℃; then, the TiO is mixed2Film immersion in 0.1M Na2And (3) carrying out cleaning and drying in the mixed solution of S methanol and water for 1min, thus finishing the deposition of the CdS quantum dots for 1 time. This process was repeated 5 times. The most difference between CdSe quantum dot deposition and CdS is that the deposition time is longer, and Na needs to be in an anion solution2SeSO3Soaking at 50 deg.c for 30min to deposit 8 layers of CdSe. And finally covering the surface with a ZnS passivation layer 2 by using an SILAR method.
Preparation of polysulfide electrolyte
Figure BDA0002001213860000071
Reference to The preparation of polysulfides (Soo-Yong Lee, Min-Ah Park, Jae-Hong Kim, et al, Journal of The Electrochemical Society,160(11), H847-H851,2013), mixing Na with sodium2S·9H2O (2M), S (2M) and KCl (0.2M) in 7ml methanol and 3ml H2And O, putting the mixture into a water bath at 50 ℃ and stirring for 1 h.
(IV) MnCo2S4Performance test of virtual symmetrical battery assembled by/CNTs composite counter electrode
Scraping the prepared counter electrode to 0.16cm2The active area of the electrode is increased, then three surfaces of the active coating are adhered with insulating adhesive tapes, then two counter electrodes are assembled into a symmetrical electrode with a sandwich structure, electrolyte is injected between the electrodes through an injector, and the time is waited for 5-10 min. The assembled symmetric electrode was tested for Electrochemical Impedance Spectroscopy (EIS), Bode plots (Bode plots), and Tafel polidationcurves (Tafel polistringcurves).
(V) counter electrode and TiO2QDSSCs (quantum dots for direct light scattering) testing photovoltaic performance assembled by/CdS/CdSe/ZnS photoanode
And assembling the prepared counter electrode and the photo-anode into a sandwich structure, dripping electrolyte, and waiting for 5-10 min. And carrying out a photocurrent density-photovoltage (J-V) test under standard sunlight to characterize the photovoltaic performance of the counter electrode.
Example 4
(I) MnCo2S4Preparation of counter electrode
1) Preparation of Mn-Co precursor
To 200ml of ethanol was added 0.422g of Mn (OAc)2·4H2O、0.858g Co(OAc)2·4H2O and 1.018g of urea, after stirring well, were warmed to 85 ℃ and refluxed at this temperature for 2 h. After cooling to normal temperature, the product is collected by centrifugal washing with ethanol three times, and finally dried in a vacuum drying oven at 50 ℃ for 12 h.
2)MnCo2S4Preparation of
0.08g of the precursor and 0.12g of thioacetamide are weighed and added into 40ml of ethanol to be stirred for 10min, and then the solution is transferred into a hydrothermal reaction kettle to react for 6h at 120 ℃. After the reaction is finished, cooling to normal temperature, and centrifugally washing for many times by deionized water and ethanol. And finally drying in a vacuum drying oven at 50 ℃ for 12 h.
3) Preparation of counter electrode
And uniformly dripping the prepared sample on the FTO conductive glass surface cleaned in advance at the solubility of 5mg/ml ethanol, and heating and drying to obtain the counter electrode.
(di) TiO2Preparation of/CdS/CdSe/ZnS photo-anode
The preparation of photoanodes is referred to the literature (Chandu V.V.Muralee Gopi, Seenu Ravi, et al, Scientific Reports, volume 7, particle number:46519(2017)), with the difference that:
coating the slurry of titanium dioxide on FTO conductive glass by a spin coating method, coating 6 layers, and calcining in a muffle furnace at 500 ℃ for 30 min. Three quantum dots were deposited using sequential ionic layer reactive adsorption (SILAR). First, TiO is mixed2Film immersion in 0.1MCd (CH)3COO)2Ethanol solution for 1min, and deionized water for cleaning excessive Cd on the surface2+Drying at 60 ℃; then, the TiO is mixed2Film immersion in 0.1M Na2And (3) carrying out cleaning and drying in the mixed solution of S methanol and water for 1min, thus finishing the deposition of the CdS quantum dots for 1 time. This process was repeated 5 times. The most difference between CdSe quantum dot deposition and CdS is that the deposition time is longer, and Na needs to be in an anion solution2SeSO3Soaking at 50 deg.c for 30min to deposit 8 layers of CdSe. And finally covering the surface with a ZnS passivation layer 2 by using an SILAR method.
Preparation of polysulfide electrolyte
Figure BDA0002001213860000081
Reference to The preparation of polysulfides (Soo-Yong Lee, Min-Ah Park, Jae-Hong Kim, et al, Journal of The Electrochemical Society,160(11), H847-H851,2013), mixing Na with sodium2S·9H2O (2M), S (2M) and KCl (0.2M) in 7ml methanol and 3ml H2In O mixed liquid, placingStirred in a water bath at 50 ℃ for 1 h.
(IV) Performance testing of virtual symmetric Battery assembled from pairs of electrodes
Scraping the prepared counter electrode to 0.16cm2The active area of the electrode is increased, then three surfaces of the active coating are adhered with insulating adhesive tapes, then two counter electrodes are assembled into a symmetrical electrode with a sandwich structure, electrolyte is injected between the electrodes through an injector, and the time is waited for 5-10 min. The assembled symmetric electrode was tested for Electrochemical Impedance Spectroscopy (EIS), Bode plots (Bode plots), and Tafel polidationcurves (Tafel polistringcurves).
(V) counter electrode and TiO2QDSSCs (quantum dots for direct light scattering) testing photovoltaic performance assembled by/CdS/CdSe/ZnS photoanode
And assembling the prepared counter electrode and the photo-anode into a sandwich structure, dripping electrolyte, and waiting for 5-10 min. And carrying out a photocurrent density-photovoltage (J-V) test under standard sunlight to characterize the photovoltaic performance of the counter electrode.
Example 5
Preparation of (mono) CNTs counter electrode
And uniformly dripping CNTs on the surface of FTO (fluorine doped tin oxide) conductive glass cleaned in advance at the solubility of 5mg/ml ethanol, and heating and drying to obtain the counter electrode.
(di) TiO2Preparation of/CdS/CdSe/ZnS photo-anode
The preparation of photoanodes is referred to the literature (Chandu V.V.Muralee Gopi, Seenu Ravi, et al, Scientific Reports, volume 7, particle number:46519(2017)), with the difference that:
coating the slurry of titanium dioxide on FTO conductive glass by a spin coating method, coating 6 layers, and calcining in a muffle furnace at 500 ℃ for 30 min. Three quantum dots were deposited using sequential ionic layer reactive adsorption (SILAR). First, TiO is mixed2Film immersion in 0.1MCd (CH)3COO)2Ethanol solution for 1min, and deionized water for cleaning excessive Cd on the surface2+Drying at 60 ℃; then, the TiO is mixed2Film immersion in 0.1M Na2And (3) carrying out cleaning and drying in the mixed solution of S methanol and water for 1min, thus finishing the deposition of the CdS quantum dots for 1 time. This is achieved byThe process was repeated 5 times. The most difference between CdSe quantum dot deposition and CdS is that the deposition time is longer, and Na needs to be in an anion solution2SeSO3Soaking at 50 deg.c for 30min to deposit 8 layers of CdSe. And finally covering the surface with a ZnS passivation layer 2 by using an SILAR method.
Preparation of polysulfide electrolyte
Figure BDA0002001213860000091
Reference to The preparation of polysulfides (Soo-Yong Lee, Min-Ah Park, Jae-Hong Kim, et al, Journal of The Electrochemical Society,160(11), H847-H851,2013), mixing Na with sodium2S·9H2O (2M), S (2M) and KCl (0.2M) in 7ml methanol and 3ml H2And O, putting the mixture into a water bath at 50 ℃ and stirring for 1 h.
(IV) Performance testing of virtual symmetric Battery assembled from pairs of electrodes
Scraping the prepared counter electrode to 0.16cm2The active area of the electrode is increased, then three surfaces of the active coating are adhered with insulating adhesive tapes, then two counter electrodes are assembled into a symmetrical electrode with a sandwich structure, electrolyte is injected between the electrodes through an injector, and the time is waited for 5-10 min. The assembled symmetric electrode was tested for Electrochemical Impedance Spectroscopy (EIS), Bode plots (Bode plots), and Tafel polidationcurves (Tafel polistringcurves).
(V) counter electrode and TiO2QDSSCs (quantum dots for direct light scattering) testing photovoltaic performance assembled by/CdS/CdSe/ZnS photoanode
And assembling the prepared counter electrode and the photo-anode into a sandwich structure, dripping electrolyte, and waiting for 5-10 min. And carrying out a photocurrent density-photovoltage (J-V) test under standard sunlight to characterize the photovoltaic performance of the counter electrode.
FIG. 1 is MnCo2S4X-ray powder diffraction pattern of/CNTs composite material. In the figure, the Mn-Co precursor and the Mn-Co/CNTs precursor have diffraction peaks (JCPDS No.23-1237) with different degrees at the 2 theta of 31 degrees (220), 36 degrees (311), 44 degrees (400), 59 degrees (511) and 64 degrees (440), and the diffraction peaks are similar to the MnCo-Co precursor2O4In agreement, therefore, in the precursorThe energy component is mainly MnCo2O4. In MnCo2S4And MnCo2S4The XRD diffraction pattern of/CNTs has diffraction peaks with different degrees at 24 degrees (020), 32 degrees (311) and 40 degrees (400), which correspond to the structure of metal sulfide, and further shows that MnCo is successfully generated by hydrothermal method2S4. Further, Mn-Co/CNTs and MnCo2S4The diffraction peaks of/CNTs at around 27 ℃ and 55 ℃ are derived from CNTs.
FIG. 2 is a scanning electron micrograph of an electrode material, wherein (a) and (c) are MnCo2S4the/CNTs composite material (b) and (d) are pure MnCo2S4. The images show that the deposited CNTs form a cross-linked conductive network in the composite, with MnCo attached thereto2S4The nano particles have uniform size, and the addition of the CNTs obviously reduces MnCo2S4The size of the catalyst reduces the aggregation of crystals and creates conditions for improving the electrocatalytic activity.
Fig. 3 is an electrochemical impedance diagram of an electrode material. As can be seen from the figure, MnCo2S4Impedance ratio of/CNTs 20 composite counter electrode pure MnCo2S4The electron transfer impedance of the counter electrode and other composite counter electrodes is small, which shows that the counter electrode has the best electrocatalytic activity for the reduction of polysulfide ions. Other electrochemical parameters are listed in table 1.
Fig. 4 is a Bode diagram of the counter electrode material. The electron lifetime in the counter electrode can be calculated using τ -1/2 π fn, in FIG. 4 MnCo2S4The frequency corresponding to the phase angle peak value of the/CNTs 20 is the largest, the electron life is the shortest, and the electron life sequence corresponding to each electrode material is as follows: MnCo2S4﹥MnCo2S4/CNTs15﹥MnCo2S4/CNTs25﹥MnCo2S4/CNTs 20. The shorter the electron lifetime, indicating that the shorter the residence time of the electrons on the counter electrode, the relatively higher the electrocatalytic activity. It can also be seen from the electron lifetime that the addition of CNTs dopes MnCo2S4The metal sulfide is more than that of pure MnCo2S4The electrocatalytic activity of the counter electrode is good, and when the addition amount of the CNTs is 20 percentMnCo of2S4the/CNTs 20 showed the best electrocatalytic activity for the electrode.
Fig. 5 is a tafel polarization curve for the counter electrode material. As can be seen from the figure, MnCo2S4Exchange Current Density (J) of/CNTs 20 composite counter electrodeo) Maximum of (12.01mA · cm)2) It shows that the CNTs with the mass fraction of 20% have the best electrochemical performance. Second, MnCo mixed with CNTs2S4All compared to a single material JoIs large. Therefore, the experiment shows that the Mn-Co alloy is added into MnCo2S4The addition of CNTs as a composite counter electrode can improve MnCo2S4Electrocatalytic activity as a counter electrode alone, and MnCo2S4the/CNTs 20 composite counter electrode has the best catalytic activity. J of other electrode materials0Are listed in table 1.
TABLE 1 electrochemical parameters of different counter electrodes
Figure BDA0002001213860000101
Figure BDA0002001213860000111
FIG. 6 is a TiO-based electrode pair2J-V curve of QDSSCs assembled by/CdS/CdSe/ZnS photo-anodes. As shown, the composite counter electrode assembled QDSSCs with short circuit current (J)sc) Open circuit voltage (V)oc) The QDSSCs based on the composite counter electrode also have photoelectric conversion efficiencies (η) that are calculated to be greater than the single counter electrode material, wherein the maximum photoelectric conversion efficiency (4.85%) is compared to MnCo when the mass fraction of CNTs is 20%2S4The improvement is 62.75 percent when the electrode is used as a counter electrode. Proves MnCo2S4The electrocatalytic activity of the/CNTs composite counter electrode is superior to that of MnCo2S4A counter electrode. The photoelectric performance parameters of each pair of electrodes are shown in Table 2.
TABLE 2 photoelectric performance parameters of quantum dot sensitized solar cells assembled based on various counter electrodes
Counter electrode Jsc(mA·cm-2) Voc(V) FF η(％)
CNTs 14.63 0.41 0.39 2.37
MnCo2S4 16.20 0.46 0.40 2.98
MnCo2S4/CNTs15 17.89 0.48 0.36 3.09
MnCo2S4/CNTs20 18.45 0.58 0.45 4.85
MnCo2S4/CNTs25 18.02 0.50 0.40 3.52

Claims (10)

1. A manganese cobalt spinel sulfide composite counter electrode of a quantum dot sensitized solar cell is characterized in that: the electrode is prepared by the following specific preparation steps:
1) and (3) purifying the carbon nano tube: adding carbon nano tubes into a mixture of nitric acid and sulfuric acid, stirring, heating and refluxing; cooling to room temperature, washing the carbon nanotubes with distilled water and absolute ethyl alcohol alternately to neutrality, and drying the collected matter for further use;
2) preparation of Mn-Co/CNTs precursor: putting the purified carbon nano tube obtained in the step 1) into ethanol for ultrasonic dispersion, and then adding Mn (OAc)2·4H2O、Co(OAc)2·4H2O and urea, fully stirring, and heating and refluxing; after the temperature is reduced to normal temperature, centrifugally washing the product by using ethanol for three times, collecting the product, and finally drying the product in a vacuum drying oven at 50 ℃ for 12 hours;
3)MnCo2S4preparation of/CNTs: dissolving the precursor obtained in the step 2) and thioacetamide in ethanol, performing magnetic stirring, and transferring the solution to a hydrothermal kettle for reaction; after the reaction is finished, centrifugally washing the reaction product for multiple times by using deionized water and ethanol, and finally drying the reaction product in a vacuum drying oven at 50 ℃ for more than 12 hours;
4) assembling the electrodes: uniformly dripping the sample obtained in the step 3) on a conductive substrate at the solubility of 5mg/ml ethanol, and heating and drying to obtain a counter electrode; then, scraping the counter electrode into a square active area, and sticking packaging glue on the left, right and lower three sides of the square active area; and finally assembling the paired electrodes.
2. The electrode of claim 1, wherein: in the step 1), the carbon nano tube is an industrial multi-wall carbon nano tube or a single-wall carbon nano tube; the volume ratio of the nitric acid to the sulfuric acid is 1: 3-1: 3.5; the heating reflux temperature is 80 ℃, and the time is 1-2 hours.
3. The electrode of claim 1, wherein: in step 2), Mn (OAc) is added2·4H2O、Co(OAc)2·4H2The mass ratio of O to urea is 1:2.033: 2.412.
4. The electrode of claim 1, wherein: in step 2), weighing CNTs and Mn (OAc)2·4H2The mass ratio of O is 1: 4.396.
5. The electrode of claim 1, wherein: in step 2), weighing CNTs and Mn (OAc)2·4H2The mass ratio of O is 1: 3.297.
6. The electrode of claim 1, wherein: in step 2), weighing CNTs and Mn (OAc)2·4H2The mass ratio of O is 1: 2.637.
7. The electrode of claim 1, wherein: in the step 2), the heating reflux temperature is 85 ℃, and the time is 2-3 hours.
8. The electrode of claim 1, wherein: in the step 3), the concentration contents of the precursor and thioacetamide in ethanol are respectively 2mg/ml and 3 mg/ml; stirring for 10-20 min; the hydrothermal reaction temperature is 110-130 ℃; the heat preservation time is 5-7 h.
9. The electrode of claim 1, wherein: in the step 4), the conductive substrate is an FTO transparent conductive substrate or an ITO transparent conductive substrate, and the drying temperature is 50-80 ℃.
10. The method for preparing a manganese cobalt spinel sulfide composite counter electrode of a quantum dot sensitized solar cell according to any one of claims 1 to 9.
CN201910213260.XA 2019-03-20 2019-03-20 Manganese cobalt spinel sulfide composite counter electrode of quantum dot sensitized solar cell Pending CN111724995A (en)

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