Study On Preparation Of Organic Framework Compound Based Carbon Materials As Counter Electrodes For Dsscs

For meeting energy demand,the dye sensitized solar cells（DSSCs）become one of the heat pots of present research area.As an important part of DSSCs,the counter electrode（CE）serve as the reduction of I₃^-and transferring electrons.However,the most widely used platinum（Pt）counter electrodes are too expensive and the long-term stability is not ideal,which limited the industrial production and commercialization of DSSCs.It is necessary to find an alternative materials.Carbon is one of rich abundance in nature,it has relatively low cost,and comparably high chemical and thermal stability.It possesses a tunable surface area and multiple structural forms at atomic/nanoscale that define an unusually broad range of physicochemical properties to satisfy diverse application.In this paper,two organic framework compounds were respectively used as precursors to construct two porous carbon materials:in-situ boron-doped nanosheets structure vertically linked on the surface of reduced GO（v BNS-G）and nitrogen-doped porous carbon materials with Zn atoms loaded（m NC）.By using various electrochemical methods,the catalytic activity and chemical reaction kinetics of I₃^-reduction,and DSSCs were assembled to test the its photovoltaic performance.The research contents as follows:1.Using two-step synthesis method,which enables growth of ultrathin COF-1 nanosheets vertically oriented on the surface of GO,carbonization of this nanocomposites under the protection of molten salt allows the porous carbon materials with boron-doped nanosheets structure vertically linked on reduced GO.A series of v BCNS-G samples were synthesized using variation of loading ratio of benzene-1,4-diboronic acid（DBA）（DBA:DBA-GO=1:2,1:3,1:4）.Finally,v BCNS-G-3 showed the best electrochemical performance of I₃^-reduction,and the photoelectric conversion efficiency of DSSCs manufactured by v BCNS-G-3 CEs reached 9.21%,better than the performance of the Pt CEs（7.67%）.This is due to the synergistic effect of B-doped carbon nanocrystals and graphene substrate.B-doped carbon nanocrystals provide abundant reactive sites,graphene and carbon nanosheets facilitates the charge transfer,and the porous structure conducive to diffusion of electrolyte.2.Using metal-organic framework compound Ru/ZIF-8 as the precursor,that has been transformed into porous nitrogen doped carbon overlayer under the high temperature condition.Besides,the simultaneous pyrolysis of Ru/ZIF-8 shell accompanied by the assembling of Zn particles was beneficial to obtain the uniformly small-sized Zn cluster,the properties of the materials were optimized at the temperature of 800℃,900℃,1000℃and 1100℃.When the pyrolysis at 1000℃,m NC-1000 as DSSCs CEs obtained 10.21%PCE,which was better than Pt electrode.Because of the porous structure increased the contact area between electrode material and electrolyte,reduced the interfacial transfer resistance.The co-existence of N,Zn and Ru atoms provides abundant active sites for the I₃^-reaction and improves the conductivity of CEs,alleviated the electron recombination.