Photoelectrochemical Properties Of Two-dimensional Sulfide Nanosheets And Its Composites

Due to the energy shortage and environmental pollution,the new energy utilization has been focused in recent years.Among these,semiconductor photocatalytic technology is considered to be the most promising technology for the direct conversion from the solar energy to the chemical energy.TiO2 nanorod array is widely used in photocatalysis and solar cells due to its ordered physical structure,large specific surface area and high carrier transport capacity.However,only the ultraviolet light,4%of the sunlight could be absorbed,since the bandgap of TiO2 nanorod arrays is about 3.2 eV.Moreover,in TiO2 nanorods array,the photoelectric conversion is restricted by the higher carrier's recombination.With great performance of graphene,two dimensional sulfides catch more and more attention for their visible light absorption,high electronic transmission and lager specific surface area.Therefore,the photoelectric conversion could be possibly improved by compositing these two dimensional sulfide materials with TiO2.In this work,the two dimensional sulfide nanosheets and corresponding TiO2 nanorod composites were fabricated.Our work was mainly focused on following three aspects.1.Preparation and electrocatalytic properties of Rhenium disulfide(ReS2)nanosheets.ReS2 nanosheets were prepared on carbon paper by the hydrothermal method.Its electrocatalytic performance was investigated by the reactant concentration,temperature and time modification.However,unanticipatedly,the ReS2 prepared in our system had no light response.2.Preparation and photoelectrochemical properties of ReS2/TiO2 compositing system.TiO2 nanorods array were prepared on the FTO conductive glass by the hydrothermal method.The TiO2 nanorods array with the best photoelecltric conversion efficiency was obtained by changing the preparation conditions.Then the ReS2 nanosheets were loaded on TiO2 nanorods array by the hydrothermal method,and its photoelectrochemical properties were carefully studied.The separation efficiency and carrier migration efficiency of photogenerated electron-hole pairs in TiO2 nanorods array were markedly increased by ReS2 nanosheets loading,which worked as electrocatalysts,although no light response was detected in them.Taking the saturated photocurrent density of this composite material at 1.6 V bias as an example,it was about 1.3 times high compared to that in TiO2 nanorods array.3.Preparation and photoelectrochemical properties of SnS2 nanosheets.SnS2 nanosheets were prepared on carbon paper by the hydrothermal method,and the optimized preparation condition was obtained.As a preliminarily application,the photocatalytic degradation rate about 70%of methylene blue(MB)by SnS2 nanosheets was realized.