Investigation On Microstructure Control,Modification And Properties Of CuInS₂ Photoelectrode

Photoelectrocatalytic decomposition of water to produce hydrogen can convert solar energy into clean hydrogen energy.It has a very broad application prospect in solving energy crisis and environmental pollution problems,and has been receiving the attention of researchers in recent years.The development of low-cost,high-activity and high-stability semiconductor materials as photoelectrodes is the key to photocatalytic decomposition of water to produce hydrogen.In this paper,CuInS₂ nanofilms were prepared by hydrothermal method.By adjusting the[Cu^2+]/[In³⁺]molar ratio and reactant concentration of hydrothermal precursor solution,different microstructures of CuInS₂ nanofilms were prepared.The influence of microstructure on photoelectric properties of CuInS₂ nanofilm was studied,In order to further improve its photoelectric properties,the composite modification of CuInS₂ nanofilm was carried out by Pt co-catalyst and metal sulfide semiconductor Sb₂S₃ respectively.The composite structures of CuInS₂/Pt,CuInS₂/Sb₂S₃ and CuInS₂/Sb₂S₃/Pt were prepared by electrodeposition and low-temperature hydrothermal method respectively.The morphology,phase and photoelectric properties of the prepared samples were tested and characterized.The effects of microstructure on the properties were investigated.The influence mechanism of co-catalyst and heterojunction on the performance of semiconductor photoelectrodes was discussed.The results show that the[Cu²⁺]/[In³⁺]molar ratio and reactant concentration have an important influence on the photoelectric properties of CuInS₂ nanofilms.When the[Cu²⁺]/[In³⁺]molar ratio is 0.4,the maximum photocurrent density is up to-0.79mA/cm²;when the reactant concentration is 8 mM copper chloride,20 mM indium chloride and 60 mM thioacetamide,the maximum photocurrent density is-0.76 mA/cm²,due to its smaller crystal size and better crystallinity.The photocurrent densities of CuInS₂/Pt,CuInS₂/Sb₂S₃ and CuInS₂/Sb₂S₃/Pt composite structure optical electrodes constructed respectively reached-1.96 mA/cm²,-1.86 mA/cm² and-2.48 mA/cm² at the voltage of-0.6 V vs.RHE,which were 2.48,2.35 and 3.13 times of the photocurrent densities of single CuInS₂ nanofilm?-0.79 mA/cm²?.The reasons are as follows:?1?After the composite modification of CuInS₂ nanofilms with Sb₂S₃ semiconductor,the absorption of the material is further improved,and the utilization efficiency of sunlight is increased;?2?CuInS₂ and Sb₂S₃ have an appropriate energy band matching,and this gradient energy level structure promotes the separation of photogenerated carriers.?3?Pt co-catalyst assisted in the capture of photogenerated electrons further promoted the separation of carriers and effectively inhibited the recombination of carriers.