Preparation Of Sb₂Se₃ Photocathode By Rapid Thermal Evaporation And Its Photoelectrochemical Properties For Water Splitting

With the rapid development of economic globalization and rural urbanization,the shortage of traditional fossil fuels is becoming more and more serious.As an effective way to solve energy and environment problems,the conversion of solar energy to hydrogen energy by photoelectric chemical water decomposition cells has attracted the attention of a large number of researchers.P-type semiconductor antimony selenide（Sb₂Se₃）is a binary compound with suitable band gap（～1.2 eV）and high absorption coefficient(>5×10⁵ cm^-1),cheap,low toxicity and simple element composition,it is expected to be an efficient photocathode material for hydrogen production by photoelectrochemical water decomposition.However,in the photocathode of Sb₂Se₃,intrinsic defects and grain boundary problems of Sb₂Se₃ lead to high photocarrier recombination rate and poor stability caused by CdS photocorrosion and co-catalyst Pt shedding.In this paper,firstly,Sb₂Se₃ was prepared by rapid thermal evaporation method,and the influence of in-situ pressure annealing time on the absorption layer of Sb₂Se₃ and the hydrogen production performance of photocathode was investigated.Secondly,the influence of TiO₂/N-GO as a protective layer on the stability of the photoelectrochemical water decomposition of Sb₂Se₃ was investigated.The details are as follows:（1）The absorption layer of Sb₂Se₃ was optimized by changing the annealing time,and then loaded with CdS/Pt to improve the photoelectric performance of hydrogen production by photoaurora electrochemical water decomposition of Sb₂Se₃.Sb₂Se₃ thin films were prepared by rapid thermal evaporation,and the one-step preparation strategy of in-situ pressure annealing was explored.Inert gas Ar gas was added into the cavity to inhibit the back evaporation of the thin films.Sb₂Se₃ optical absorption layer with good crystallization and adjustable thickness was prepared by adjusting in situ annealing time and optimizing Sb₂Se₃ optical absorption layer.Then,the SLG/Mo/Sb₂Se₃/CdS/Pt photocathode was prepared by loading CdS/Pt on the surface.XRD,SEM,KPFM and other characterization methods show that the recrystallization of Sb₂Se₃ during annealing process results in better crystallinity,grain boundary density and fewer Se vacancy defects,which are favorable for photogenic carrier transport.When the annealing time is 120 s,the prepared Sb₂Se₃ absorbing layer has large grain size,appropriate thickness and fewer Se vacancy defects.The photocurrent density of SLG/Mo/Sb₂Se₃/CdS/Pt photocathode can reach 13.4 mA·cm^-2 at 0 V_RHE bias when AM 1.5G simulated sunlight test is performed.（2）The photoelectric performance and stability of Sb₂Se₃ photoelectrochemical water decomposition were improved by the introduction of TiO₂/N-GO protective layer.In order to further improve the photocurrent density and stability of Sb₂Se₃ photocathode,TiO₂ was prepared by atomic layer deposition（ALD）method and nitrogen doped graphene oxide（N-GO）layer was prepared by spin coating method.The photocathode with SLG/Mo/Sb₂Se₃/CdS/TiO₂/N-GO/Pt structure was successfully constructed.The photocurrent and stability of SLG/Mo/Sb₂Se₃/CdS/TiO₂/N-GO/Pt photocathode are significantly improved compared with SLG/Mo/Sb₂Se₃/CdS/Pt photocathode,which is partly because the introduction of TiO₂ increases the curvature of the built electric field and accelerates the separation of photogenerated carriers.On the other hand,not only nitrogen atoms but also defects are introduced after nitrogen doping treatment.Nitrogen atoms can be used as catalytic active centers,and defects may play a certain anchoring role for co-catalyst Pt,thus improving the photoelectric performance and stability of hydrogen production by photoaurora electrochemical water decomposition of Sb₂Se₃.