The Performance Of Tungsten-based Catalytic Composites Pyrolysis By Polyoxotungstate For Efficient Counter Electrode In Dye-sensitized Solar Cell

Dye-sensitized solar cells（DSSCs）are environmentally friendly cells that directly store and further utilize solar energy.The counter electrode（CEs）of the battery performs the basic functions of the device through catalytic reduction of the electrolyte.Traditional counter electrode catalyst is precious metal Pt,which has limited reserves and is easily corroded by iodine electrolyte.Therefore,the development of non-Pt counter electrode material with efficient and stable performance is one of the keys to achieve large-scale commercial application of DSSCs.In this paper,tungstic polyacid was used as tungsten source,and different organic compounds were added as carbon source to prepare the precursor,and then tungsten counter electrode catalyst material was synthesized by pyrolysis and applied to DSSCs.The specific research content are as follows:1.The tungstic polyacid(H₃PW₁₂O₄₀·XH₂O)was used as tungsten source and melamine（C₃H₆N₆）as carbon source,tungsten precursors were constructed by ball milling method,and four different N-doped W₂C electrode materials were successfully prepared by temperature gradient pyrolysis,which characterized by XRD,SEM,XPS,EDS and electrochemical test.The electrode material obtained at pyrolysis temperature of 800℃has the highest catalytic activity and photoelectric conversion efficiency of 7.01%.In addition,chemical and hydrothermal methods were used to construct the precursor,and then the prepared material was combined with carbon nanotubes to improve the efficiency.Results the composite prepared by hydrothermal method had the best performance and the efficiency was only 5.85%.2.The H₃PW₁₂O₄₀·XH₂O was first anchored in the pores of the copper complex,and then four precursors with different proportions were synthesized by combining different volumes of pyrrole and pyrolyzed at high temperature.Then optimized the pyrolysis time of the precursor（4,5,6,7 h）.In the preparation of different W₂C@C composites,when the volume of pyrrole was 0.15 m L,the W₂C@C-0.15Py composites synthesized by pyrolysis for 6 h had the largest specific surface area and uniformly dispersed gaps,which was conducive to the rapid of electrolyte ions transfer,so that the material exhibits the highest catalytic activity and good stability,and the power conversion efficiency was as high as 7.08%.3.The H₃PW₁₂O₄₀·XH₂O and Py was used as raw material,the molar ratio of the two was changed,and five kinds of precursors with unique structure were synthesized by one-pot hydrothermal method.WO₂materials with different morphology and catalytic performance were successfully prepared by high temperature pyrolysis,which material has the highest efficiency of 5.74%.The catalytic performance of the composite was enhanced and the conversion efficiency was increased to 6.11%when the composite was combined with the two-dimensional conductive carrier graphene oxide（GO）with high conductivity and large specific surface area.