The Synthesis And Performance Of Vanadium Oxide/Carbon Composite As A Counter Electrode Catalyst For Triiodide/Iodide Redox Couple In Dye-Sensitized Solar Cell

The counter electrodes of Dye-Sensitized Solar Cells（DSCs）have been performed to reduce production costs and to achieve high cell performance.As the counter electrode materails,platinum（Pt）is preferred due to its superior conductivity and high electrocatalytic activity.However,platinum is a very expensive,scarce noble metal and it undergoes slow dissolution due to the corrosive iodide/triiodide（I^-/I₃^-）redox electrolyte,which deteriorates its long-term stability.Metal oxides are also best-opted materials to replace the Pt counter electrode in DSCs due to their low cost,good thermal properties,and high catalytic activity.Some semiconductor oxides have been shown to increase the catalytic activity for the reduction of triiodide to iodide.Carbonaceous materials are quite attractive to replace the platinum electrode in DSCs due to their high electronic conductivity,large surface area,corrosion resistance towards iodine,high reactivity for triiodide reduction,and low cost.Then combining the advantages of the above metal oxides and carbon materials,a more promising way to reduce the cost of DSCs is to explore other low-costing materials that possess reasonably good catalytic activity.V₂O₅ was synthesized by different procedures employing thermal decomposition,sol-gel and hydrothermal methods which were subsequently introduced into DSCs as counter electrodes（CEs）catalysts for the regeneration of traditional iodide/triiodide（I^-/I₃^-）redox couple.Four different methods were used to synthesize vanadium oxide with different morphologies.The photovoltaic performance of solar cells,employing prepared V₂O₅ as CE was investigated.Moreover it was observed that the addition of citric acid can reduce the charge transfer resistance and alter the catalytic activity of vanadium oxide.The V₂O₃/C composites were prepared by adding different proportions of activated carbon to the V₂O₃/C composites by the method of calcining ammonium metavanadate under nitrogen protection.And the structure and catalytic properties of the prepared materials were characterized.The results show that the composite material has higher PV performance than single material,and the middle ratio of 2: 3 is the best,which is attributed to the synergetic cooperation between vanadium oxide and activated carbon.Using starch,dextrin and soluble sugar glucose as carbon materials with V₂O₅ in hydrogen peroxide solution produced by sol in different ratio match,according to participate in the sol reaction and not participate in sol formation of sol for two kinds of different forms of precursor,under different temperature and time,the products were characterized,and use it as the counter electrode in the application of the DSCs.Particles in the sol reaction and the non-reactive co-sol were calcined at high temperature under nitrogen,and vanadium trioxide was obtained when the ratio was low.When the proportion of carbohydrates increased,the samples were mixed with sugars to varying degrees after calcination.As sugar percentage increase samples with different level of sugar mixed carbon after calcining,when the residual carbon produced carbon composite material,the electrical conductivity of the material are improved,and the current density in the 2:1 samples show the efficiency of the best,when expanded to 4:1 excessive carbon added to lower the properties of the composites.Starch samples were sol by changing the conditions of temperature and the vanadium carbide containing a small amount of vanadium trioxide impurity efficiency reaches up to 5.6%.