Preparation And Photoelectric Properties Of Carbon-Based Oxide Composite Catalytic Electrode Materials

As a member of the third generation of solar cells,dye-sensitized solar cells have attracted attention because of their low cost,simple preparation process and environmental friendliness.Typically,the DSSCs consists of a nanoporous TiO₂ film,a dye photosensitizer,an electrolyte containing a redox couple?usually triiodide/iodide?and a counter electrode?CE?.Among them,the counter electrode is a key component that affects the photoelectric conversion efficiency of the dye-sensitized solar cell.Platinum?Pt?is the most commonly used counter electrode catalytic material with excellent electrical and electrocatalytic activity.However,platinum reserves are limited,expensive,and easily corroded by iodine electrolytes,affecting the life and stability of the battery,which is not conducive to large-scale practical applications.Therefore,it is necessary to develop a counter electrode catalytic material that can replace the platinum source,which is earth-abundant,efficient and low-cost.In the second chapter,carbon nanofibers?CNFs?were first prepared by electrospinning.Fe₂O₃/CNFs,a composite electrode material for carbon fiber-supported ferric oxide was synthesized by a simple hydrothermal method in dye-sensitized solar cells?DSSCs?.Scanning electron microscopy showed that Fe₂O₃ nanoparticles were uniformly supported on the surface of CNF,providing a rich catalytic active site for the reduction of I₃^-to I^-.The one-dimensional CNFs have high conductivity,can effectively reduce the agglomeration of Fe₂O₃ nanoparticles,increase the specific surface area of the material,and facilitate the rapid transport of ions and electrons in the electrolyte.The synergistic effect of the two enabled Fe₂O₃/CNFs exhibiting higher catalytic performance.The composite material was sprayed on the FTO conductive substrate to form a counter electrode?CE?assembled into DSSCs with an open circuit voltage of 0.718V,a short circuit current density of 16.75 mA cm^-2,a fill factor of0.62,and a photoelectric conversion efficiency of 7.48%,higher than Pt CE?6.97%?.The element-abundant and environmentally friendly composite electrode materials are expected to be an efficient alternative to traditional Pt electrodes.In the third chapter,NiCo₂O₄/CNFs,a carbon nanofiber-coated NiCo₂O₄ nanosheet composite counter electrode catalytic material was successfully synthesized by hydrothermal method with urea as precipitant and used as the counter electrode of dye-sensitized solar cell.The open circuit voltage of the NiCo₂O₄/CNFs composite counter electrode is 0.736V,the short circuit current density is 17.11 mA cm^-2,and the fill factor is 0.62,achieving a power conversion efficiency of 7.8%,higher than CNFs?5.75%?and platinum electrode?7.35%?.Compared with CNFs,NiCo₂O₄/CNFs composites have a significant improvement in the electrocatalytic performance of reduced triiodide.Due to the synergy effects between CNFs and NiCo₂O₄,NiCo₂O₄/CNFs behaved higher efficiency and electrochemical stability.In the fourth chapter,using PVP as a linker,the carbon nanofiber-loaded NiMoO4nanoparticle composite counter electrode catalytic material NiMoO4/CNFs was successfully synthesized by hydrothermal method and used as a counter electrode catalytic material for dye-sensitized solar cells.The open-circuit voltage of the DSSCs reached 0.803V,the short-circuit current was 15.79 mA cm^-2,and the fill factor was 0.60.Finally,the photoelectric conversion efficiency of 7.67%was achieved,exceeding the platinum electrode?7.17%?and the carbon fiber-based counter electrode?5.65%?.