Preparation And Photoelectric Properties Of SnO₂ Based Composite Counter Electrode

As an important part of dye-sensitized solar cells?DSSCs?,the counter electrode functions to adsorb and catalyze the reduction of I₃^-and collect external circuit electrons.The faster the reduction of I₃^-in the battery,the better the photoelectric response.The traditional counter electrode is coated with a layer of metal Pt on the conductive glass.However,the cost of Pt limits the commercial development of DSSCs.Therefore,it is important to explore low-cost and highly catalytic alternative materials as a counter electrode.As a material with excellent conductivity and catalysis,and widely distributed,carbon material is currently the most alternative material for electrode research.However,the carbon material has problems such as low catalytic activity and easy corrosion and peeling off.Therefore,in this paper,graphene and carbon nanotubes were separately doped into SnO₂ to prepare composite counter electrode,and the effects of carbon materials on the morphology and properties of SnO₂ were investigated.The catalytic performance of I₃^-reduction was investigated when they were used as counter electrodes.The main research contents and results are as follows:The SnO₂ and CNT/SnO₂ composites were successfully prepared by hydrothermal method.It was found that the incorporation of CNT into SnO₂enhanced the mechanical stability of the carbon film and formed a loose porous network structure which facilitated the diffusion of the electrolyte.S o that the redox reaction in the electrolyte can proceed more fully.The composite counter electrode prepared by EHD technology has better catalytic performance than the SnO₂ counter electrode and the CNT counter electrode.At the same time,the effects of different CNT contents on the electrochemical performance of the composite electrode were investigated.It was found that the optimum percentage of CNT was 6%,the charge transfer resistance of the electrode was 3.53?·cm² and the cathode current density was 0.77 mA·cm^-2,the assembled DSSC achieved the conversion efficiency of4.44%.The SnO₂ and graphene/SnO₂ composites were successfully prepared by sol-gel method.The morphology analysis found that the incorporation of graphene into SnO₂ reduces the agglomeration between the sheets and exposes more graphene boundary active sites,which is more conducive to the catalytic reaction.It shows the best catalytic activity for I₃^-reduction.The composite counter electrode prepared by EHD technology has better catalytic performance than the SnO₂ counter electrode and the graphene counter electrode.At the same time,the effect of different graphene doping amount on the electrochemical performance of the composite counter electrode was investigated.When the graphene concentration was 2.5 mg/mL,the DSSC obtained the conversion efficiency was 3.39%.