| The energy source is the basis for human beings’ survival and growth.As global warming increases,energy technology in the 21 st century is moving in a new direction-the search for sustainable,cleaner energy sources.Fuel cells seem to be the most prospective source of clean energy and are of great interest to national governments around the world.As an essential part of fuel cells,proton exchange membranes(PEMs)play a very crucial role in their proton conduction properties.In order to improve the efficiency of fuel cells,it is necessary to improve the conductivity of PEM,so it is urgent to find some cheap materials that can exhibit excellent proton conductivity.At present,the materials used in proton exchange membranes are mainly polymers,metal-organic frameworks(MOFs)and covalent organic frameworks(COFs),while there are few reports of hydrogenbonded organic framework materials(HOFs)used to make proton exchange membranes.However,as a class of materials rich in hydrogen bonds,it is foreseeable that HOFs as proton conductors should have great prospects and are worth exploring and challenging.Therefore,in this paper,seven different iHOFs are designed and synthesized,the application potential of this series of iHOFs in proton conduction is explored,and proton exchange membranes are designed and prepared to study their application potential in fuel cells.Discussion I:Four ionic hydrogen-bonded organic framework materials(iHOFs 5-8)were synthesized by slow diffusion of solvents using four naphthalenedisulfonic acid derivatives and 1,1’-diamino-4,4’-bipyridine diiodide(DBpy-21)as organic ligands.PXRD,TGA,SCXRD and other methods were used to characterize the structure and properties of the four crystals.The results showed that the highest proton conductivity of iHOF-5 reached 2.8 × 10-4 S·cm-1 at 100℃ and 98%RH,the maximum proton conductivity of iHOF-6 was 3.0 × 10-4 S·cm-1,the highest proton conductivity of iHOF-7 was 5.2 × 10-4 S·cm-1,and the proton conductivity of iHOF-8 was the best,reaching 4.5 × 10-3 S·cm-1 at 85%RH and 100℃.Furthermore,based on the high proton conductivity of iHOF-8,composite films with different doping ratios were prepared by doping it into the SPEEK/CS matrix.The test results show that the highest proton conductivity of 15%-iHOF-8/SPEEK and 15%-iHOF-8/CS composite membranes can reach 5.1 × 10-3 and 5.7 × 10-3 S·cm-1,respectively.Discussion Ⅱ:A case ionic hydrogen-bonded organic framework material(iHOF-9)was synthesized by 1,3,5-Tris(4-sulfophenyl)benzene(H3PSA)and 1,1’-diamino-4,4’-bipyridine diiodide(DBpy·2I)as organic ligands by solvent slow diffusion method.The structure and properties of iHOF-9 were studied,and the results displayed that there was a dense 2D hydrogen bond network,and when the proton conductivity of iHOF-9 was studied,it was found that it reached a maximum of 5.02 × 10-3 S·cm-1 at 98%RH and 100℃.The maximal proton conductivity of the 9%-iHOF-9/Nafion composite membrane can reach 1.6 × 10-1 S·cm-1,which is 3.9 times better than that of the recast Nafion membrane.9%iHOF-9/Nafion composite membrane can reach a maximal power density of 73.5 mW·cm-2,which is 1.47 times higher than the 50 mW·cm-2 of the recast Nafion,and even 9%-iHOF-9/Nafion composite membrane can reach a maximal current density of 599.4 mA·cm-2,which is superior to that of recast Nafion.Tetrasodium salt 1,3,6,8-pyrenetetrasulfonate(H4PSB)and 1,1 ’-diamino-4,4’-bipyridine diiodide(DBpy·2I)were selected as ligands,and an ionic hydrogen-bonded organic framework material(iHOF-10)was synthesized by solvothermal method,and its structure and properties were studied by PXRD,TGA,SCXRD and other means,and the findings of the proton conductivity test indicate a maximum proton conductivity is 1.49 × 10-4 S·cm-1 at 98%RH and 100℃.A case of ionic hydrogen-bonded organic framework material(iHOF-11)was synthesized by Hexa(4-sulphonato)phenylbenzene(H6PSC)and 1,1’-diamino-4,4’-bipyridine diiodide(DBpy·2I)by solvothermal method,and the proton conductivity test results indicated that the maximum proton conductivity was 1.3 × 10-1 S·cm-1 at 98%RH and 100℃.The proton-based composite membranes of varying percentages were prepared by remodelling.And the proton conductivity test results showed that the proton conductivity of the 9%-iHOF-11/Nafion composite membrane can be obtained a maximum of 1.7 × 10-1 S·cm-1.The maximum power density of 9%-iHOF-11/Nafion composite membrane was 104.69 mW·cm-2,which is 2.09 times higher compared to recast Nafion,the maximum current density is 599 mA·cm-2,which is 1.8 times higher compared to recast Nafion. |
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