WO2018111777A1

WO2018111777A1 - Pore size engineering of porous carbonaceous materials using covalent organic frameworks

Info

Publication number: WO2018111777A1
Application number: PCT/US2017/065627
Authority: WO
Inventors: Xiangfeng Duan; Chain Lee
Original assignee: The Regents Of The University Of California
Priority date: 2016-12-12
Filing date: 2017-12-11
Publication date: 2018-06-21

Abstract

A method of forming a porous carbonaceous material includes: (1) providing at least two different monomers; (2) polymerizing the monomers to form a covalent organic framework; and (3) heating the covalent organic framework to form the carbonaceous material.

Description

PORE SIZE ENGINEERING OF POROUS CARBONACEOUS MATERIALS USING COVALENT ORGANIC FRAMEWORKS

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 62/433,149, filed December 12, 2016, the contents of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] This disclosure generally relates to porous carbonaceous materials formed from covalent organic frameworks.

BACKGROUND

[0003] Oxygen Reduction Reaction (ORR) is of importance for energy conversion technologies involving fuel cells, water splitting, and batteries. Much efforts have been dedicated to the development of high performance transition metal-based catalyst as a cost- effective replacement of platinum on carbon (Pt/C). Porous frameworks have been applied for the suspension of transition metal catalyst for ORR, many with performances comparable or even surpassing Pt/C. Porous carbonaceous materials, which are often nitrogen and metal doped, have been employed as a support for catalysts to facilitate their ORR activities.

[0004] It is against this background that a need arose to develop the embodiments described herein.

SUMMARY

[0005] Some embodiments of this disclosure are directed to a strategy of molecular tuning of monomers or precursors within porous frameworks to produce controlled pore size carbon-containing (or carbonaceous) materials. In some embodiments, control of pore size is attained by controlling a length of rigid molecules and using these as monomers or precursors for annealing into porous carbonaceous frameworks. Rigid molecules encompass conjugated chemical species such as including aromatic hydrocarbons (e.g., benzene, biphenyl, triazine, pyridine, and other monocyclic or polycyclic arenes that may be substituted with cyano or other functional groups and including hetero forms thereof), alkenes (including one or more carbon-carbon double bonds), and alkynes (including one or more carbon-carbon triple bonds), and imines (including one or more carbon-nitrogen double bonds).

[0006] In some embodiments, an approach of controlling pore size includes blending in sequentially longer monomers or precursors, along with a starting monomer of covalent triazine frameworks (CTFs), which produces CTFs with sequentially larger pore sizes. This is unlike other synthesis, which involves a single starting monomer.

[0007] It is demonstrated that the approach can produce sequentially larger pore sized CTFs, and, after high temperature thermal annealing at about 700 °C to about 1000 °C, resulting carbonaceous materials retain their incrementally larger pores. With the approach, tuning of pores to different sizes can be attained to within several nanometers of each other. The surface area to volume ratio of the materials can be adjusted by varying different monomers and blended monomer ratios.

[0008] Though pore size also can be tuned to some extent by organically synthesizing sequentially larger molecules, this approach is difficult to scale, and is constrained by the ability to synthesize desired precursors.

[0009] Embodiments encompass other monomers or precursors beyond using cyano-containing or substituted molecules as precursors. Other precursors can also include functional groups such as an amide group (-(C=0) H₂), a boronic acid or ester group (- B(OH)₂ or -B(OR)(OR') where R and R' are independently hydrogen or a hydrocarbon group), a boronate anhydride group (-B(OH)-O-B(OH)-), a borosilicate group, an amine group (- H₂) and an aldehyde group (-(C=0)H) which can form an imine linkage with the amine group, and a hydrazine group (- H-NH₂) (or a hydrazide group (-(C=0)- H- H₂)) and an aldehyde group which can form a hydrazone linkage with the hydrazine group (or the hydrazide group). The strategy of molecular expansion continues to apply, in which a molecular length of precursors is tuned to influence a pore size of both a synthesized framework and a post-annealed carbonized material.

[0010] Due to their robustness, chemically functionalized nitrogen, streamlined synthesis, and pore control of annealed CTFs, there is a significant advantage of using molecularly tuned and annealed CTFs within applications in which porous carbonaceous materials are desired. Commercial carbon black is a conductive, porous form of carbon. However, its pore size distribution is random and difficult to control. Other approaches for controlling pore size include templating and temperature control. In templating, there is a constraint by the template that is used, and templating may involve very corrosive acids in an etching process. For temperature control, the pore size can be enlarged randomly, and large temperature variations may result in relatively small enhancements in porosity. There is also a constraint by temperatures at which a material can accommodate.

[0011] Through the approach of molecular tuning of precursors of CTFs, it is demonstrated that conductive, porous forms of carbon, which contain tunable pore sizes, can be formed. The approach allows incremental control of pore size distributions to range from about 1-3 nm, to about 1-5 nm, and to about 1-8 nm for some embodiments. Characterization is performed of these pores sizes through low temperature nitrogen gas absorption techniques and Density Functional Theory (DFT) calculations. Further molecular tuning can lead to a broad range of pore sizes, allowing for a selective pore diameter and volume within a porous, conducting carbonaceous material.

[0012] Molecular tuning can produce desirable materials for applications such as molecular and gas sieves, adsorbents, and electrodes. The selectivity through molecular tuning can allow for investigation of optimum pore aperture, volume, and surface area to enhance performance for various applications which specify use of porous materials. This is especially significant in materials which should be electrically conductive, such as for fuel cells and batteries. Fuel cell supports are affected by pore size. The supports can benefit from pore tunability, since they specify high surface area materials, which can deliver maximum mass transfer of reactant to a catalytic interface. Battery cathodes and anodes also can benefit from tunable porous carbonaceous materials since they rely on conducting high surface area materials. Supercapacitors rely on conductivity and surface area. However, accessibility of an usable surface area may pose a challenge. Molecular tuning can enhance and optimize porous carbonaceous materials for high performance supercapacitors.

[0013] Other aspects and embodiments of this disclosure are also contemplated. The foregoing summary and the following detailed description are not meant to restrict this disclosure to any particular embodiment but are merely meant to describe some embodiments of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a better understanding of the nature and objects of some embodiments of this disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying drawings. [0015] Figure 1. Scheme 1 - Schematic representation of the synthesis of cobalt- chelated covalent triazine frameworks (Co-CTFs) with different pore sizes. The strategy of creating sequentially longer trimered units from the synthesis of CTFs using a single monomer, and mixed monomers are displayed. The cubes represent different Co-CTFs and their enhanced pore size.

[0016] Figure 2. Pore size characterization, (a) N₂ Brunauer-Emmett-Teller (BET) isotherms, (b) Differential pore volume overlays of Co-CTFs. (c) Bar graph of specific surface areas corresponding to each size pore, (d) Double layer capacitance slope comparisons of Co-CTF-S, -M, and -L are illustrated. Corresponding electrochemical surface area (ECSA) calculated and listed according to Co-CTFs.

[0017] Figure 3. Cumulative pore volumes of Co-CTF-S (lower curve), -M (middle curve), and -L (top curve).

[0018] Figure 4. Electrochemical surface area cyclic voltammetry (CV) curves of Co-CTF-S, -M, and -L.

[0019] Figure 5. Electrochemical Performance, (a) Overlay of different Co-CTF linear scan voltammetry (LSV) curves measured at about 1600 r.p.m. in about 0.1 M KOH. Labels indicate pores sizes small (S), medium (M) and large (L). (b) Kinetic current density and Ei_/2 on the y-axes, plotted against different pore sizes on the x-axis. (c) Nyquist plot overlays of Co-CTFs. Labels indicating Co-CTFs of pores sizes small (S), medium (M) and large (L) (d) Representative CV curve of Co-CTF-L under saturated gas N₂ or 0₂ using about 0.1 M KOH electrolyte, (e) Co-CTF-L LSV curve comparison with about 20 wt.% Pt/C at about 1600 r.p.m. in about 0.1 M KOH. (f) Koutecky-Levich (K-L) plot of Co-CTF-L.

[0020] Figure 6. Peroxide current measured on a rotating ring-disk electrode of Co- CTF-L.

[0021] Figure 7. Active catalyst evaluation, (a) Powder X-ray diffraction (PXRD) overlay of Co-CTF-L before and after acid etching, (b) LSV overlay of Co-CTF-L before and after acid etching in about 0.1 M KOH electrolyte. Labels represent Co-CTF-L, and post acid etching of Co-CTF-L for Figures 7(a) and (b). (c) and (d) Images of Co-CTF-L.

[0022] Figure 8. XRD of pre-etched Co-CTF-S, -M, and -L.

[0023] Figure 9. X-ray photoelectron spectroscopy (XPS) data of survey and nitrogen of Co-CTF-L.

[0024] Figure 10. XPS Spectrum of Cobalt 2p of Co-CTF-L. [0025] Figure 11. Electron imaging of Co-CTF-L. (a) Low magnification transmission electron microscopy (TEM) image, (b) Energy dispersive X-ray (EDX) mapping of Co-CTF-L. (c) High angle annular dark field scanning transmission electron microscopy (HAADF-STEM) low magnification image of Co-CTF-L. (d) HAADF-STEM high magnification image of Co-CTF-L. Scale bars are 200 nm (a), 100 nm (b), 5 nm (c), and 1 nm (d).

[0026] Figure 12. Stability in LSV of Co-CTF-L with initial sweep (lower curve), and post 10,000 cycles (upper curve).

[0027] Figure 13. Measuring Density Functional Theory (DFT) differential pore volume of varied stoichiometric ratios between CTF-L starting monomers.

[0028] Figure 14. DFT differential pore volume measurements of a same sample, CTF-L, after about 400 °C sublimation and about 900 °C annealing.

[0029] Figure 15. Additional molecular tuning pore size measurements using DFT calculations from BET measurements.

[0030] Figure 16. Scheme 2 - Trimerization of 4,4'-biphenyl dicyanobenzene (BPDC) into a triazine polymer. Upon metal chelation and annealing, the structure becomes disordered and includes cobalt particles. Images of the transition from polymer, to metal chelation, and annealed material are displayed.

[0031] Figure 17. (a) Low magnification TEM image of Co-CTF. (b) Scanning electron microscopy (SEM) image of Co-CTF, showing large cavernous pores, (c). High resolution TEM (HRTEM) image of graphitically wrapped cobalt nanoparticle. (d) BET nitrogen isotherm of Co-CTF. Curve with squares represents absorption, and curve with circles represents desorption. (e) I-V curve performed on bulk sample of Co-CTF.

[0032] Figure 18. (a) EDX mapping of Co-CTF. (b) XPS survey spectrum of Co- CTF. (c) Nitrogen Is spectrum displays different types of nitrogen bonding, (d) Cobalt 2p spectrum displays cobalt ion peaks.

[0033] Figure 19. (a) Different LSV curves of Co-CTF in both acidic and basic electrolytes, along with Pt/C as a comparison, (b) Rotating ring-disk electrode (RRDE) measurements in both acidic and basic electrolytes displaying LSV and peroxide currents at different rotation speeds, (c) Stability measurements plotted by number of cycles along with change in current, (d) Electron transfer numbers bar graph of Co-CTF in both acidic and basic electrolytes, with Pt/C as a comparison. [0034] Figure 20. (a) LSV of Co-CTF, along with stability after 2000 cycles. Pt/C added for comparison, (b) Comparison chart of different transition metal-based F£ER catalysts along with Co-CTF.

DETAILED DESCRIPTION

[0035] Introduction:

[0036] Supported catalysts derived from temperature treating frameworks are appealing since they possess high surface area, abundant nitrogen content, and can include a variety of metals. Covalent triazine frameworks (CTFs), a subclass of covalent organic frameworks (COFs), have a wide range of applications in gas storage, heterogeneous catalysis, and energy storage applications. Applications of CTFs in ORR are desirable due to their ability to bind metals, high nitrogen content, and full π-conjugation. More specifically, CTFs built from 2,6-dicyanopyridine (DCP) ligand most significantly benefit the catalytic performance since a bipyridine moiety is produced from nitrile trimerizations, which create an open site for metal chelation.

[0037] With respect to these framework-based catalyst supports, it is desired to consider the importance of porosity details, such as pore volume, surface area, electrochemical surface area, and so forth. Here, some embodiments are directed to the principle of pore expansion and its influence on the ORR activity of a supported transition metal catalyst. Pursuing incremental higher porosity, synthesis is performed of two CTFs, by adding stoichiometric amounts of either 1,4-dicyanobenzene (or 1,4-benzenedicarbonitrile) (DCB) or 4,4'-biphenyl dicyanobenzene (or 4,4'-biphenyldicarbonitrile) (BPDC) to the DCP monomer (as illustrated in Scheme 1 in Figure 1). The streamlined synthetic approach overcomes multiple difficulties of producing high porosity: (i) avoiding tedious organic synthesis techniques, (ii) maintaining full conjugation, and (iii) ability to bind transition metals. Tuning the pore sizes of CTFs, and using them as precursors for annealing, resulted in three robust frameworks which maintained sequentially higher specific surface areas, and also successively increased electrochemical surface areas. Here evaluation is made of the progressive pore tuning, and report is made of their correlation to oxygen reduction behavior in alkaline electrolyte. It is found that the largest pore size supported electrocatalyst, Co- CTF -L, has exceptional ORR performance, with half-wave over-potential of about 38 mV lower than that of commercial Pt/C.

[0038] Results and Discussion: [0039] As shown in Scheme 1, the approach includes adding long, slim organic linkers to the DCP monomer, therefore increasing the length of each trimered unit and cobalt chelation sites, hence expanding the pores. DCP is chosen as a starting monomer, since its CTF derivatives show metal chelations, and good electrochemical applications. Initially, the CTFs were formed through ZnCl₂ methods and adding mixed monomers when desired as outlined in Scheme 1. In the mixed monomer scenario, a DCP ratio to DCB or BPDC was at about 1 :2 respectively. After synthesis at about 400 °C, the CTFs were washed using copious amounts of about 0.1 M HC1 and tetrahydrofuran (TUF). Cobalt chelation to the CTFs was performed by submerging the material in a CoCl₂/ethanol solution (about 1 mg/mL) for about 24 h. A visible de-coloration of the metal solution could be observed, after which the CTFs were washed several times with ethanol, removing any excess non-chelated cobalt. To activate the electrocatalyst, aid in conductivity, and facilitate strong bond formation, the CTFs were annealed at about 900 °C for about 2 h in about 90: 10 mixture of Ar:H₂ for all samples. The pyrolized materials are noted in relation to their pore size of small (Co-CTF-S), medium (Co-CTF-M), and large (Co-CTF-L). The treatment temperature of about 900 °C performs well with the material in terms of ORR.

[0040] Pore size evaluations began with using N₂ adsorption techniques for each material. The corresponding surface areas were determined through Brunauer-Emmett-Teller (BET) analysis to be about 425, about 780, about 1480 m² g^"1 for Co-CTF-S, Co-CTF-M, and Co-CTF-L respectively (Figure 2a). The isotherm shapes of Co-CTF-M and Co-CTF-L are type-IV, which contain a typical hysteresis loop due to nitrogen fragility artifact during mesopore desorption.

[0041] Although it is important to obtain higher surface areas, expanded pore sizes are also desired and should be confirmed. Evidence of actual pore expansion was determined using Density Functional Theory (DFT) methods to calculate specific pore volumes and their corresponding pore widths. As expected, pore size distributions widen with mixed monomelic Co-CTFs as seen in Figure 2b, where differential pore volumes of Co-CTF-S, -M, and -L are overlaid. Pore widths enlarge from about 1-3 nm pores in Co-CTF-S, to ranging about 1-4.5 nm for Co-CTF-M, and finally reaching about 1-8 nm distributions in Co-CTF-L. Total pore volumes also rise respectively with pore size from about 0.23 cm³ g^"1 to about 0.40 cm³ g^"1 to about 0.89 cm³ g^"1. The pore specific surface area corresponding to pore widths are displayed in a bar graph of Figure 2c. These distributions were derived from Cumulative Pore Volume Graphs in Figure 3. [0042] Since pore accessibility of an 0.1 M KOH electrolyte may differ from N₂ gas diffusions from BET measurements in Co-CTFs, electrochemical surface area (ECSA) calculations were derived from double-layer capacitance (C_di) measurements by sweeping cyclic voltammetry (CV) at different rates in a region without Faradaic current (Figure 4). The C_di capacitance from CV progress from about 5.5 mF cm^"2, to about 31 mF cm^"2, and finally about 49 mF cm^"2 as pores expand, a near 10-fold increase. These C_di measurements translate into specific capacitances of about 14 F g^"1, about 78 F g^"1, and about 122 F g^"1 respectively. C_di values can be computed into ECSA's of about 60 m² g^"1, to about 380 m² g^"1, reaching about 606 m² g^"1 respectively, shown in Figure 2d. The experiments demonstrate that pore tuning of Co-CTFs increase surface area, and also C_di and ECSA. These factors play major roles for oxygen reduction by aiding in: reactant delivery, access of surfaces for catalysis, ionic conduction, and product removal from pores.

[0043] A strong correlation between ORR activity and pore size of the CTFs was observed. Figure 5a overlays the linear scan voltammetry (LSV) curves of the three Co-CTF samples with different pore sizes. As pore size increases, a significant enhancement of both kinetic slope and the diffusion limiting current can be achieved. Calculated kinetic current densities and Ei_/2 wave potentials are plotted against the respective Co-CTFs in Figure 5b. Improving kinetic performance can be attributed to four major ways: decreasing the activation barrier, increasing the temperature, increasing the reactant concentration, and increasing the number of possible reaction sites. The kinetic improvements can be accredited to the latter two: a greater rate of exchange between reactant and product, and also an increase in accessibility to catalytic sites, both originating from pore size engineering.

[0044] In addition to kinetic and diffusion enhancements, progressive charge transport and ion diffusion are observed, which are confirmed using impedance spectroscopy. Nyquist plots displayed in Figure 5c identify the reduced charge transfer resistance between electrode and electrolyte as pore sizes increases, observed through smaller semi-circle diameters. The improved diffusion efficiency is further confirmed in the shorter 45° Warburg region incline.

[0045] A representative CV curve of Co-CTF-L is displayed in Figure 5d. Cyclic scans of N₂ saturated KOH solution show the absence of the characteristic ORR cathodic peak. Upon 0₂ electrolyte saturation a strong peak at about 0.86 V appears. The ORR activity of the Co-CTF-L sample is further compared with an about 20 wt.% Pt/C. As shown in Figure 5e, a steep kinetic slope is induced by the large pore size and results in an impressive Ei/2 of Co-CTF-L that is about 38 mV less than that of Pt/C (about 0.87 V versus about 0.83 V in Figure 5e). Figure 5f displays Koutecky-Levich (K-L) plot of Co-CTF-L. The linearity indicates first order rate kinetics, which aligns well with electron transfer number (n) of about 3.98 measured through peroxide current on a rotating ring-disk electrode (RRDE) in Figure 6. This is very close in line with commercial Pt/C, which has theoretical n of about 4.0.

[0046] Co-CTF samples were treated with about 0.5 M H₂S0₄ in order to dissolve away most of the large cobalt particles and unstable atoms. Comparing the post acid treated material with powder X-ray diffraction (PXRD) analysis in Figure 7a reveals most of the cobalt has been removed; yet the ORR performance improves. The weak signal signifies the significantly reduced content, and the peak broadness is indicative of small particles. LSV curves measured for the post acid treatment gave a slight improvement in overall performance, resulting in higher diffusion limiting current especially at about 0.76 V in Figure 7b. These results indicate that the active ORR species in the Co-CTFs are not the large particles but likely small clusters and possibly atomic cobalt species.

[0047] Catalyst uniformity throughout the Co-CTFs was confirmed using PXRD and X-ray photoelectron spectroscopy (XPS). Figure 8 displays the overlapping Co 111 and Co 200 at peak positions of about 44.3° and about 51.5° from pre-etched Co-CTFs samples. Nitrogen XPS spectroscopy (Figure 9) displays just pyridinic (about 398.6 eV) and pyrrolic (about 400.5 eV) bands throughout the three Co-CTFs, which are the two types of ORR active nitrogen species.

[0048] Cobalt 2p spectrums in Figure 10 designate uniform bands at about 781.1 and about 796.2 eV corresponding to Co 2p_3/2 and Co 2pi_/2, for the three Co-CTFs_. The about 15.1 eV separation, along with satellite peaks, indicates the presences of cobalt ion species. The non-observance of cobalt metal may be attributed to the sampling depth of XPS. At the moment, the specific form of cobalt in ORR catalyst remains to be confirmed, whether it is large particles, small clusters, or single atoms. It is possible that in transition metal-nitrogen- carbon systems, the main contribution in electrochemistry comes from small clusters and single atoms, which is the case for iron-nitrogen-carbon ORR catalysts.

[0049] Low magnification transmission electron microscopy (TEM) image in Figure 11a displays the presence of graphitic ribbons, amongst the CTF, along with remaining cobalt particles that were not etched away. Elemental maps of carbon, nitrogen, and cobalt were obtained through energy dispersive X-ray (EDX) analysis under high resolution TEM (URTEM) (Figure 1 lb). To investigate the presence of smaller clusters and possible single atoms, an aberration corrected High Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) is used under dark field imaging (Figure 11c). An atomic resolution image of a sub-5 nm cobalt particle is captured in Figure l id. The highly crystalline Co⁰ particles are confirmed by (111) facet with d-spacing of about 2.2 A, which correlates well with the PXRD in Figure 7. It should be noted that a low accelerating voltage of about 80 kV was used to avoid electro-beam induced damage of the CTF and clusters.

[0050] The durability of Co-CTF-L was tested by using CV tests for 10,000 cycles in a range about 0.4-1.2 V. LSV curves of initial and post 10,000 cycles show just slight decay of about 12 mVs at E_½ wave in Figure 12. Through these tests, the kinetic slope in the post 10,000 cycles LSV curve remains unchanged.

[0051] The molecular tuning strategy is investigated by changing the ratios of blended monomers. Here, it is observed that increasing the amount of BPDC, a longer linker than DCP, results in the pore stretching. The cavity opening is mainly prevalent in the about 5-12 nm range as observed from the differential volume graph of Figure 13. A slight reduction in pore volume between about 2 to 5 nm is also measured.

[0052] To further confirm the high temperature stability and structural integrity of CTFs under thermal annealing, measurement is made of differential volumes of CTF-L at both about 400 °C sublimation and about 900 °C annealing, as shown in Figure 14. Nearly no changes were observed between the two samples. The very slight variation is most likely attributed to the normal float that is present in BET sample measurement. Here it can be confirmed that thermal annealing even at temperatures as high as about 900 °C does not noticeably change the structure of CTFs.

[0053] As the evaluation moves towards a full series of expansions, the strategy holds true for several more materials. Figure 15 displays the DFT differential pore volume distributions of 4 different CTFs, from size 'M', along with varied stoichiometric ratios of size 'L' and lastly BPDC. The incremental pore expansion holds true for all 4 compounds. BPDC being the longest monomer, and when used solely as the starting material, produces a highly mesoporous CTF.

[0054] Conclusion:

[0055] The effects of pore size tuning and pore volume on electrochemical performances of using cobalt-containing CTFs as precursors have been systematically investigated. Increased surface area, larger pore volumes, and higher ECS As improve reactivity and diffusion for oxygen-saturated electrolytes. Moreover, increased charge transfer and enhanced diffusion are achieved. To summarize, a strategy is developed to enhance the efficiency of Co-CTF catalysts. This pore expansion strategy is applicable to various electrocatalyst designs.

[0056] Example Embodiments:

[0057] First Aspect

[0058] In some embodiments, a method of forming a porous carbonaceous material includes: (1) providing at least two different monomers; (2) polymerizing the monomers to form a covalent organic framework; and (3) heating the covalent organic framework to form the carbonaceous material.

[0059] In some embodiments of the method, the at least two different monomers have different molecular weights. In some embodiments, the at least two different monomers have different molecular lengths along their longest dimensions.

[0060] In some embodiments of the method, a first monomer of the monomers is a N-heterocyclic arene. In some embodiments, the N-heterocyclic arene includes a 6-membered ring structure. In some embodiments, the N-heterocyclic arene is a pyridine. In some embodiments, the N-heterocyclic arene or the pyridine is substituted with at least one functional group configured to form a covalent linkage with a corresponding functional group. In some embodiments, the N-heterocyclic arene or the pyridine is substituted with at least one cyano group. Other functional groups include an amide group, a boronic acid group, a boronic ester group, a borosilicate group, an amine group, an aldehyde group, a hydrazine group, and a hydrazide group. In some embodiments, the first monomer is 2,6- dicyanopyridine. In some embodiments, the first monomer is represented by a chemical formula:

where R and R' are cyano groups, or can be independently selected from other functional groups listed above. [0061] In some embodiments of the method, a second monomer of the monomers is an arene. In some embodiments, the arene includes a 6-membered ring structure. In some embodiments, the arene is devoid of nitrogen in its ring structure. In some embodiments, the arene includes two or more 6-membered ring structures that are bonded to one another. In some embodiments, the arene is a benzene. In some embodiments, the arene is a biphenyl. In some embodiments, the arene is a triphenyl (e.g., /?ara-triphenyl) or a higher order phenyl. In some embodiments, the arene is substituted with at least one functional group configured to form a covalent linkage with a corresponding functional group. In some embodiments, the arene is substituted with at least one cyano group. Other functional groups include an amide group, a boronic acid group, a boronic ester group, a borosilicate group, an amine group, an aldehyde group, a hydrazine group, and a hydrazide group. In some embodiments, the second monomer is 1,4-dicyanobenzene or 4,4' -biphenyl dicarbonitrile. In some embodiments, the second monomer is represented by a chemical formula:

where R" and R" are cyano groups, or can be independently selected from other functional groups listed above, and n is an integer that is 1, 2, 3, or greater.

[0062] In some embodiments of the method, a molar ratio of the first monomer to the second monomer is in a range of about 1 : 15 to about 2: 1, such as about 1 : 10 to about 1 : 1, about 1 :8 to about 1 : 1, about 1 :6 to about 1 : 1, about 1 :4 to about 1 : 1, or about 1 :2 to about 1 : 1. In some embodiments, the molar ratio of the first monomer to the second monomer is about 1 : 1 or less than about 1 : 1.

[0063] In some embodiments of the method, polymerizing the monomers is performed in the presence of a catalyst, such as zinc chloride. In some embodiments, polymerizing the monomers includes heating at a temperature in a range of about 250 °C to about 550 °C, about 300 °C to about 500 °C, or about 400 °C for a time duration in a range of about 20 h to about 60 h, about 30 h to about 50 h, or about 40 h.

[0064] In some embodiments of the method, polymerizing the monomers includes forming covalent linkages between the monomers. In some embodiments, polymerizing the monomers includes forming triazine moieties. In some embodiments, the triazine moieties are bonded to one another via linkers. In some embodiments, the linkers are represented by a chemical formula:

where n is an integer that is 1, 2, 3, or greater.

[0065] In some embodiments of the method, heating the covalent organic framework is performed at a temperature in a range of about 700 °C to about 1000 °C, about 800 °C to about 1000 °C, or about 900 °C for a time duration in a range of about 0.5 h to about 5 h, about 1 h to about 3 h, or about 2 h.

[0066] In some embodiments of the method, the method includes, prior to heating the covalent organic framework, exposing the covalent organic framework to a solution of a metal salt. In some embodiments, the metal salt includes a transition metal. In some embodiments, the transition metal is cobalt. In some embodiments, heating the covalent organic framework includes forming the carbonaceous material including the transition metal incorporated therein. In some embodiments, the transition metal incorporated in the carbonaceous material is in the form of nanoparticles, such as having sizes in a range of about 1 nm to about 100 nm, about 1 nm to about 80 nm, about 1 nm to about 60 nm, about 1 nm to about 40 nm, about 1 nm to about 20 nm, about 1 nm to about 10 nm, or about 1 nm to about 5 nm. Alternatively, or in conjunction for some embodiments, the transition metal incorporated in the carbonaceous material is in the form of atomic species.

[0067] Second Aspect

[0068] In additional embodiments, a method of forming a porous carbonaceous material includes: (1) providing a monomer; (2) polymerizing the monomer to form a covalent organic framework; (3) exposing the covalent organic framework to a solution of a transition metal; and (4) heating the covalent organic framework to form the carbonaceous material incorporating the transition metal.

[0069] In some embodiments of the method, a monomer is an arene. In some embodiments, the arene includes a 6-membered ring structure. In some embodiments, the arene is devoid of nitrogen in its ring structure. In some embodiments, the arene includes two or more 6-membered ring structures that are bonded to one another. In some embodiments, the arene is a benzene. In some embodiments, the arene is a biphenyl. In some embodiments, the arene is a triphenyl (e.g., ?ara-triphenyl) or a higher order phenyl. In some embodiments, the arene is substituted with at least one functional group configured to form a covalent linkage with a corresponding functional group. In some embodiments, the arene is substituted with at least one cyano group. Other functional groups include an amide group, a boronic acid group, a boronic ester group, a borosilicate group, an amine group, an aldehyde group, a hydrazine group, and a hydrazide group. In some embodiments, the monomer is 1,4- dicyanobenzene or 4,4' -biphenyl dicarbonitrile. In some embodiments, the monomer is represented by a chemical formula:

[0070] In some embodiments of the method, polymerizing the monomer is performed in the presence of a catalyst, such as zinc chloride. In some embodiments, polymerizing the monomer includes heating at a temperature in a range of about 250 °C to about 550 °C, about 300 °C to about 500 °C, or about 400 °C for a time duration in a range of about 20 h to about 60 h, about 30 h to about 50 h, or about 40 h.

[0071] In some embodiments of the method, polymerizing the monomer includes forming covalent linkages between molecules of the monomer. In some embodiments, polymerizing the monomer includes forming triazine moieties. In some embodiments, the triazine moieties are bonded to one another via linkers. In some embodiments, the linkers are represented by a chemical formula:

where n is an integer that is 1, 2, 3, or greater.

[0072] In some embodiments of the method, the transition metal is cobalt. In some embodiments, the transition metal incorporated in the carbonaceous material is in the form of nanoparticles, such as having sizes in a range of about 1 nm to about 100 nm, about 1 nm to about 80 nm, about 1 nm to about 60 nm, about 1 nm to about 40 nm, about 1 nm to about 20 nm, about 1 nm to about 10 nm, or about 1 nm to about 5 nm. Alternatively, or in conjunction for some embodiments, the transition metal incorporated in the carbonaceous material is in the form of atomic species.

[0073] In some embodiments of the method, heating the covalent organic framework is performed at a temperature in a range of about 700 °C to about 1000 °C, about 800 °C to about 1000 °C, or about 900 °C for a time duration in a range of about 0.5 h to about 5 h, about 1 h to about 3 h, or about 2 h.

[0074] Third Aspect

[0075] In some embodiments, a resulting carbonaceous material has a surface area of about 400 m² g^"1 or greater, about 500 m² g^"1 or greater, about 600 m² g^"1 or greater, about

700 m 2 g^" 1 or greater, about 800 m 2 g^" 1 or greater, about 900 m 2 g^" 1 or greater, about 1000 m 2 g^" 1 or greater, about 1100 m 2 g^" 1 or greater, about 1200 m 2 g^" 1 or greater, about 1300 m 2 g^" 1 or greater, or about 1400 m² g^"1 or greater, and up to about 1500 m² g^"1 or greater.

[0076] In some embodiments, pores of the carbonaceous material having sizes in a range of about 1 nm to about 20 nm account for at least 90% of a total pore volume within the carbonaceous material. In some embodiments, pores of the carbonaceous material having sizes in a range of about 1 nm to about 12 nm account for at least 90% of a total pore volume within the carbonaceous material. In some embodiments, pores of the carbonaceous material having sizes in a range of about 1 nm to about 8 nm account for at least 90% of a total pore volume within the carbonaceous material. In some embodiments, pores of the carbonaceous material having sizes in a range of about 1 nm to about 5 nm account for at least 90% of a total pore volume within the carbonaceous material. In some embodiments, pores of the carbonaceous material having sizes in a range of about 1 nm to about 3 nm account for at least 90% of a total pore volume within the carbonaceous material.

[0077] In some embodiments, a total pore volume within the carbonaceous material is about 0.2 cm³ g^"1 or greater, about 0.3 cm³ g^"1 or greater, about 0.4 cm³ g^"1 or greater, about 0.5 cm³ g^"1 or greater, about 0.6 cm³ g^"1 or greater, about 0.7 cm³ g^"1 or greater, or about 0.8 cm³ g^"1 or greater, and up to about 0.9 cm³ g^"1 or greater.

[0078] In some embodiments, an electrical conductivity of the carbonaceous material is about 2 S/cm or greater, about 4 S/cm or greater, about 6 S/cm or greater, about 8 S/cm or greater, about 10 S/cm or greater, about 12 S/cm or greater, about 14 S/cm or greater, about 16 S/cm or greater, or about 18 S/cm or greater, and up to about 20 S/cm or greater. [0079] In some embodiments, the carbonaceous material includes carbon and nitrogen, and an atomic percentage of nitrogen within the carbonaceous material is about 2% or greater, about 4% or greater, about 6% or greater, about 8% or greater, or about 10% or greater, and up to about 12% or greater. In some embodiments, the carbonaceous material includes carbon, nitrogen, and a transition metal, and an atomic percentage of the transition metal within the carbonaceous material is about 2% or greater, about 4% or greater, about 6% or greater, about 8% or greater, or about 10% or greater, and up to about 11% or greater.

Examples

[0080] The following examples describe specific aspects of some embodiments of this disclosure to illustrate and provide a description for those of ordinary skill in the art. The examples should not be construed as limiting this disclosure, as the examples merely provide specific methodology useful in understanding and practicing some embodiments of this disclosure.

Example 1

Molecular Tuning of Covalent Triazine Frameworks for Pore Size Control [0081] Experimental:

[0082] Synthesis of CTFs. CTF-S: 2,6-dicyanopyridine (DCP) was mixed in an about 1 : 1 molar ratio with anhydrous ZnCl₂ (about 2 grams total weight) and flame sealed in a quartz tube. The tube was placed in a furnace at about 400 °C for about 40 h, where the CTF was then washed with copious amounts of about 1.0 M HC1, tetrahydrofuran (TUF), and acetone. Synthesis of CTF-M: Monomers in about 1 :2 molar mixture of DCP and 1,4- dicyanobenzene (DCB), along with a substantially equal molar amount of anhydrous ZnCl₂, were flame sealed in a quartz tube and followed the same post-synthesis procedure above. Synthesis of CTF-L: Monomers in about 1 :2 molar mixture of DCP and 4,4'-biphenyl dicyanobenzene (BPDC), along with a substantially equal molar amount of anhydrous ZnCl₂, were flame sealed in a quartz tube and followed the same post-synthesis procedure above.

[0083] Synthesis of Co-CTFs. To metallate the CTFs, about 40 mg of desired CTF was immersed in about 20 mL of CoCl₂/ethanol solution (about 1 mg/mL). The vial was allowed to react for about 24 h in which a noticeable de-coloration occurred. The excess cobalt solution was then decanted, and the remaining CTF washed twice with ethanol then dried in air. The cobalt-bound CTFs were then placed into an aluminum boat, and heated in a quartz tube furnace with a gas flow mixture of Ar:H₂ (about 90: 10) for about 2 h. To prepare Co-CTFs for electrochemical measurements, the materials were ground into fine powders/paste using a mortar and pestle along with a few drops of ethanol.

[0084] Materials Characterization. TEM (TEM T12 Quick CryoEM) was performed to investigate the overall structure and cobalt particles. HRTEM was performed using a Titan at about 300 kV accelerating voltage. Scanning electron microscopy (Zeiss Supra 40VP) was used to evaluate the morphology of the Co-CTFs. XRD was carried out using a Bruker D8 X- ray Powder Diffractometer with Cu Ka radiation. BET isotherms and pore size data were measured using a Miromeritics Tristar II 3020. XPS (Axis Ultra DLD) was used to probe nitrogen and cobalt contents of each Co-CTF. Thermogravimetric analysis (TGA) was carried out to evaluate the cobalt loading amount using PerkinElmer instruments Pyris Diamond TG/DTA.

Example 2

Covalent Triazine Frameworks as Support for Electrocatalysts [0085] Introduction:

[0086] With the move towards increasing renewable energy sources, challenges arise on how to store excess energy and re-harvest it back. High performance electrocatalysts can help fulfill these roles, more specifically those that perform ORR and hydrogen evolution reaction (HER). Earth abundant, low-cost, efficient, and stability are the main criteria to fulfilling these challenges.

[0087] In a typical regenerative fuel cell (RFC), an electrolyzer stores energy by splitting water into H₂ and 0₂, and a fuel cell converts the chemical energy into electrical energy. In an unified regenerative fuel cell (URFC) a single module serves the dual purposes of electrolyzer and fuel cell, where the module utilizes bi-functional catalysts for both electrolysis and energy conversion. This design efficiency saves components, and also material, space, and costs.

[0088] CTFs can be desirable platforms for electrocatalysts. However, to obtain good electrochemical performance, blending with carbon is performed due to their low conductivities. Though this is a solution, this has the added effect of lowering the number of active catalyst per area and weight. Here synthesis is performed of Co-CTF, a cobalt-loaded CTF-derived material formed from super-acid polymerized triazine films. The resultant polymer when immersed into a cobalt solution can strongly chelate the metal. After high temperature annealing, the resultant Co-CTF possess desired electrochemical properties of: intrinsic conductivity, high surface area, nitrogen doping, and transition metal binding.

[0089] The CTF and cobalt play synergistic roles for each other. Cobalt aids in the graphitization of the CTF, allowing the framework to achieve metallic-like conductivities, as well as remaining an active catalyst to enhance ORR and HER. The CTF upon graphitization now acts as a desirable electrocatalytic support, aiding the cobalt with surface area, diffusion, and electron transport across a three-dimensional (3D) framework.

[0090] Experimental:

[0091] Co-CTF was formed using metal binding followed by high-temperature treatment (Scheme 2 in Figure 16). Polymerized CTF was prepared and was immersed into a cobalt chloride and ethanol solution at about 60 °C overnight, allowing for metal chelation. The CTF turned blue, indicating metal binding. The sample was washed with ethanol to remove any excess cobalt then annealed under Ar and H₂ gas at about 900 °C for about 2 h. Other annealing temperatures of about 700, about 800, and about 1000 were tested; however, about 900 °C yielded the highest ORR performance. So for further discussion, unless stated otherwise in this example, all samples were treated under about 900 °C temperature. Of note, this allows CTFs to be synthesized from super-acid and is able to absorb metal atoms from solution. This finding may lead to further applications of super-acid CTFs in membrane purifications.

[0092] Results and Discussion:

[0093] The 3D Co-CTF structure and morphology were examined by TEM and SEM (Figure 17). Hollow mesopores are visible throughout the structure along with uniformly distributed cobalt nanocrystals (NCs). Figure 17a displays a typical TEM image of the Co-CTF. The SEM image shows the mesoporous channels of Co-CTF are interconnected with micron-length oligomers that continuously run throughout the structure in Figure 17b. HRTEM and XRD (Figure 17c) identified the cobalt to be highly crystalline face-centered cubic (fee), with d-spacing of about 2.04 A corresponding to the (111) facet. These graphitically wrapped cobalt particles can dramatically improve ORR performance. Nitrogen absorption analysis gave a specific surface area of about 560 m²/g as seen in Figure 17d. A typical type I-V isotherm was observed, which is a characteristic of mesoporous materials (Figure 17e). Encouraged by the evidence of 3D conjugation, measurement is made of a bulk centimeter- sized sample using vapor deposited gold electrodes. A conductivity of about 20 S/cm is obtained at room temperature, which places Co-CTF amongst the best organic conductors. The presence of cobalt NCs aided in the graphitization and therefore conductivity enhancement, since non-cobalt thermally annealed CTFs gave a lower conductivity of about 1 x 10^"3 S/cm. Raman studies support this conclusion through comparison of honeycomb- graphitic in-plane D and G band vibrations intensities at about 1350 cm^"1 and about 1580 cm^"1 respectively. There is a significant signal to sample enhancement of several times when using equal amounts of CTF, indicating enhanced graphitization of cobalt-containing CTF.

[0094] To investigate the elemental composition of Co-CTF, EDX mappings were performed. Nitrogen atoms are uniformly distributed throughout the framework giving strong signals. Cobalt NCs are also observed to be well dispersed through the framework (Figure 18a). XPS further confirms nitrogen and cobalt content, and also the bonding environments and oxidation states (Figure 18b-d). The nitrogen N Is spectrum after annealing of Co-CTF (Figure 18c) can be de-convoluted into three peaks at: about 398.6, about 400.5, and about 401.3 eV. These peaks correspond to pyridinic, pyrrolic, and quaternary nitrogens respectively. There was some typical nitrogen loss from pyrolization, where the content decreased from a theoretical value of about 13.5% to about 11.8% analyzed using elemental analysis. The cobalt XPS displays peaks correlating to cobalt^2+/3+ ions. This signal is due to catalytic sites of cobalt chelated in Co-N fashion to pyridinic and pyrrolic nitrogens throughout the framework, which is responsible for bi-catalyst properties. Inductive coupled plasma (ICP) analysis revealed the cobalt content to be about 11%. The results indicate Co- CTF maintains its nitrogen group functionality throughout the annealing process, and may omit ammonia treatment to introduce nitrogen doping which has been shown to be important for enhancing ORR performance in other approaches. Furthermore, through this intrinsic nitrogen-containing framework, high amounts of nitrogen are reached, and are not readily obtained through doping.

[0095] The ORR activities of Co-CTF were measured using a rotating-disk electrode (RDE) under acidic and alkaline electrolytes and RRDE for catalytic pathway determination. LSV curves were taken at a scan rate of about 10 mV/s in both electrolytes with overlay comparisons to commercial about 20 wt.% platinum on Vulcan carbon (Pt/C) as shown in Figure 19a. In acidic conditions, Co-CTF gave an onset potential (E_onset) of about 0.9 V vs. reversible hydrogen electrode (RUE) and diffusion limiting current density of about 4 mA/cm at about 0.6 V. Under alkaline conditions, Co-CTF outperforms Pt/C. An E_onset of about 0.98 V and a half-wave potential (E_1/2) at about 0.82 V are measured, which at this point surpasses that of Pt/C by over about 10 mV. Moreover, Co-CTF has a near 70 mV cathodic shift when comparing at about 5 mA limiting current using an about 0.7 V potential. Though some ORR is observed with non-cobalt treated CTF, it resulted in significantly larger overpotential (about 200 mV ) in comparison to Co-CTF.

[0096] RRDE measurements were performed under the same conditions with a scan rate of about 10 mV/s in their appropriate electrolytes. Extremely low peroxide oxidation currents are detected, in the micro-ampere range, as seen in Figure 19b. Calculations reveal the peroxide percentages to be below about 0.1% throughout the limiting current. Calculating the electron transfer number (n) from these values attributes Co-CTF to near total 4e^" reduction of oxygen by Co-CTF in both alkaline and acidic conditions (Figure 19d). Catalyst durability was tested by cycling Co-CTF in 0₂-saturated about 0.1 M KOH for up 10,000 cycles. By comparing data points along the onset potential to the limiting current, just minor degradation is seen in Figure 19c.

[0097] Evaluation is made of the activity of Co-CTF towards F£ER under conditions of about 0.5 M H₂S0₄ and a three-electrode system. A loading mass of about 285 μg cm^"2 on glassy carbon electrode rotating at about 2000 r.p.m. was used. For comparison, commercial Pt/C @ about 20 wt.% was loaded on the working electrode in the same mass amount. Co- CTF begins F£ER at an onset potential of about 70 mV as seen in the polarization curves of Figure 20a, overlaid with Pt/C standard whose onset is near zero. At about 10 mA of current density, Co-CTF operates at just about 200 mV overpotential. This activity is comparable, and even surpasses many other non-noble metal catalysts as shown in Figure 20b. To test the long-term resilience of Co-CTF for sustained F£ER, CV was continuously performed from about 0.2 to about -0.5 V vs. RHE in about 0.5 M H₂S0₄ for two-thousand cycles. Just a slight overpotential increase of about 8 mV was observed after this cycling, as seen in Figure 20a. The small differences in the stability curves for both ORR and TIER show Co-CTF to be a robust candidate for long-term URFC catalyst.

[0098] Conclusion:

[0099] In summary, synthesis is made of a conductive 3D framework, which includes transition metal cobalt and performs two electrocatalytic reactions, ORR and TIER with good performance. The framework, Co-CTF, includes a wide range of pores, ranging from micro- to mesoporous, many are large enough to be observed under SEM. This translates into highly accessible surface area, which optimizes diffusion attributing to Co- CTF's high performance. The results show the synergistic behavior between CTF and cobalt, where they complement each other in a thermal reaction to produce conductive 3D materials, and whose applications may be utilized in sensing, devices, and batteries. The bi-functional catalyst advances the applicability of CTFs as supports for water splitting and fuel cell applications.

[00100] As used herein, the singular terms "a," "an," and "the" may include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to an object may include multiple objects unless the context clearly dictates otherwise.

[00101] As used herein, the term "set" refers to a collection of one or more objects. Thus, for example, a set of objects can include a single object or multiple objects.

[00102] As used herein, the terms "connect," "connected," and "connection" refer to an operational coupling or linking. Connected objects can be directly coupled to one another or can be indirectly coupled to one another, such as via one or more other objects.

[00103] As used herein, the term "size" refers to a characteristic dimension of an object. Thus, for example, a size of an object that is circular or spherical can refer to a diameter of the object. In the case of an object that is non-circular or non-spherical, a size of the object can refer to a diameter of a corresponding circular or spherical object, where the corresponding circular or spherical object exhibits or has a particular set of derivable or measurable properties that are substantially the same as those of the non-circular or non- spherical object. When referring to a set of objects as having a particular size, it is contemplated that the objects can have a distribution of sizes around the particular size. Thus, as used herein, a size of a set of objects can refer to a typical size of a distribution of sizes, such as an average size, a median size, or a peak size.

[00104] As used herein, the terms "substantially" and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation. For example, when used in conjunction with a numerical value, the terms can refer to a range of variation of less than or equal to ±10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%), less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. [00105] Additionally, concentrations, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It is to be understood that such range format is used for convenience and brevity and should be understood flexibly to include numerical values explicitly specified as limits of a range, but also to include all individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly specified. For example, a range of about 1 to about 200 should be understood to include the explicitly recited limits of about 1 and about 200, but also to include individual values such as about 2, about 3, and about 4, and sub-ranges such as about 10 to about 50, about 20 to about 100, and so forth.

[00106] While the disclosure has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the disclosure as defined by the appended claims. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, method, operation or operations, to the objective, spirit and scope of the disclosure. All such modifications are intended to be within the scope of the claims appended hereto. In particular, while certain methods may have been described with reference to particular operations performed in a particular order, it will be understood that these operations may be combined, sub-divided, or re-ordered to form an equivalent method without departing from the teachings of the disclosure. Accordingly, unless specifically indicated herein, the order and grouping of the operations are not a limitation of the disclosure.

Claims

What is claimed is:

1. A method of forming a porous carbonaceous material, comprising:

providing at least two different monomers;

polymerizing the monomers to form a covalent organic framework; and

heating the covalent organic framework to form the carbonaceous material.

2. The method of claim 1, wherein the monomers have different molecular lengths.

3. The method of claim 1, wherein a first monomer of the monomers is a N-heterocyclic arene.

4. The method of claim 3, wherein the N-heterocyclic arene is substituted with at least one cyano group.

5. The method of claim 3, wherein the N-heterocyclic arene is 2,6-dicyanopyridine.

6. The method of claim 3, wherein a second monomer of the monomers is an arene including a ring structure that is devoid of nitrogen within the ring structure.

7. The method of claim 6, wherein the arene is substituted with at least one cyano group.

8. The method of claim 6, wherein the arene includes two or more ring structures that are bonded to one another.

9. The method of claim 6, wherein the arene is 1,4-dicyanobenzene or 4,4'- biphenyldicarbonitrile.

10. The method of claim 1, wherein a first monomer of the monomers is a N-heterocyclic arene, a second monomer of the monomers is an arene including a ring structure that is devoid of nitrogen within the ring structure, and a molar ratio of the first monomer to the second monomer is 1 : 1 or less.

11. The method of claim 1, wherein heating the covalent organic framework is performed at a temperature in a range of 700 °C to 1000 °C.

12. The method of claim 1, further comprising:

prior to heating the covalent organic framework, exposing the covalent organic framework to a solution of a metal salt.

13. A method of forming a porous carbonaceous material, comprising:

providing a monomer;

polymerizing the monomer to form a covalent organic framework;

exposing the covalent organic framework to a solution of a transition metal; and heating the covalent organic framework to form the carbonaceous material incorporating the transition metal.

14. The method of claim 13, wherein the monomer is an arene including two or more ring structures that are bonded to one another.

15. The method of claim 14, wherein the arene is substituted with at least one cyano group.

16. The method of claim 14, wherein the arene is a biphenyl.

17. The method of claim 13, wherein the transition metal is cobalt.

18. The method of claim 13, wherein heating the covalent organic framework is performed at a temperature in a range of 700 °C to 1000 °C.

19. A porous carbonaceous material comprising carbon and nitrogen, wherein an atomic percentage of nitrogen within the carbonaceous material is 8% or greater, and a total pore volume within the carbonaceous material is 0.2 cm³ g^"1 or greater.

20. The carbonaceous material of claim 19, wherein the atomic percentage of nitrogen within the carbonaceous material is 10% or greater.

21. The carbonaceous material of claim 19, wherein pores of the carbonaceous material having sizes in a range of 1 nm to 20 nm account for at least 90% of the total pore volume within the carbonaceous material.

22. The carbonaceous material of claim 19, wherein an electrical conductivity of the carbonaceous material is 10 S/cm or greater.

23. The carbonaceous material of claim 19, further comprising a transition metal, and an atomic percentage of the transition metal within the carbonaceous material is 8% or greater.