Study On Synthesis And Performance Of Two-Dimension Material/Metal Sulfide Composites

Two-dimension（2D）materials are promising in solar cell,water splitting and environmental remediation applications due to their unique optical and electronic properties.They possess numerous merits such as high specific surface area,superior electron mobility and high chemical stability.2D materials are regarded as an ideal candidates to prepare nanocomposites that with high performance.Metal sulfides（MxSy）,which can utilize the visible light of the sunlight spectrum,are a good visible-light photocatalyst for hydrogen evolution and organic pollutants photodegradation.However,there are two barrier that prevent the application of metal sulfides.One is the low separation efficiency of their photo-induced electrons and holes,the other one is their stability.The advantages of both materials are complementary,therefore,their composites are expected to improve the photocatalytic efficiency and the utilization of the sunlight.In this thesis,we focus on the 2D semiconductor materials and metal sulfides.Here,we report the synthesis of ultrathin g-C₃N₄ nanosheets/CdS and MoS2 nanosheets/ZnIn2S4 nanocomposites and study on their photocatalytic performance.The roles of the 2D semiconductor materials in the composites were also investigated.The systematic research involving:（1）Ultrathin g-C₃N₄ nanosheets were obtained through thermal condensation of urea followed by a facile ultrasonic method.The ultrathin g-C₃N₄ nanosheets/CdS composites were successfully synthesized by a simple solvothermal method.The result of research indicates that,intimate contact interfaces were developed between ultrathin g-C₃N₄ nanosheets and CdS nanoparticles,promoting the charge separation and the stability of the photocatalyst.（2）Ultrathin MoS2 nanosheets/ZnIn2S4 composites were synthesized via one-pot hydrothermal method.The photocatalytic activity of the as-prepared composites were evaluated by photocatalytic H2 evolution experiments.The results prove that,ultrathin MoS2 nanosheets which in the composites synthesized by one-step method,maintain enough chemical potential to reduce H+ to H2.Moreover,the intimate contact between ultrathin MoS2 nanosheets and ZnIn2S4 facilitate the separation and migration of photogenerated carriers.Thus,the photocatalytic activity and stability of composites were enhanced.（3）In order to explain that 2D semiconductor materials play an important role for improving the activity and stability of metal sulfides,we fabricate two kinds of composites,the ultrathin g-C₃N₄ nanosheets/CdS and MoS2 nanosheets/ZnIn2S4 composites.We hope that our work is able to provide a new insight for the construction of stable photocatalysts with efficient visible light activity.