Synthesis Of Noble-Metal-Free Cocatalyst Modified Perovskite Oxide Ultrathin Nanosheet Photocatalysts And Study Of Photocatalytic Hydrogen Evolution Reaction

The K⁺Ca₂Nb₃O^-₁₀ ultrathin nanosheet(marked as KCNO_us)as a two-dimensional semiconductor-based nanomaterial exfoliated from Dion-Jacobson phases layered perovskites has sparked widespread interests thanks to remarkable physical and chemical properties,high specific surface area and special electronic structure.It is notice that the conduction band of KCNO_us is composed of the high-level 4d orbital,which can generate photoelectrons with stronger reducibility to split water into hydrogen under light irradiation.However,owing to lack of active sites and easy recombination of photoinduced carriers,single-component KCNO_uss remains a critical restriction on significant application in the domain of photocatalysis technology.To solve these dilemmas,in this academic dissertation,introducing a cocatalyst was considered as an ideal pathway to achieve desired photocatalytic performance of splitting water over the main photocatalyst KCNO_us.Based on the analysis technics,the composition,morphology,photoelectric properties and hydrogen production performance were investigated.Further,the possible mechanism of photocatalytic reaction was explored.Research contents were listed as following:1.A series of Co_xP/KCNO_us heterostructures were synthesized by integrating noble-metal-free Co_xP nanoparticles on the surface of KCNO_us ultrathin nanosheets and exhibited enhanced photocatalytic hydrogen generation.Under the irradiation of xenon light,the hydrogen generation rate of resulting optimal Co_xP/KCNO_us reached up to 90.44?mol·g^-1h^-1,which was about 5.78 times higher than that of single-component KCNO_us.The apparent quantum efficiency of Co_xP/KCNO_us was1.32%at 350 nm.Based on the photoluminescence?PL?,UV-vis diffuse reflectance spectroscopy?UV-vis DRS?and photo-electrochemical analyses,the possible reasons for the improved photocatalytic activity can be ascribed to the enhanced light absorption capacity and strong separation efficiency of photoinduced carriers over Co_xP/KCNO_us heterostructures thanks to the introduction of Co_xP nanoparticles.2.A series of Ni₂P/KCNO_us nanostructures were synthesized by in-situ integrating noble-metal-free Ni₂P nanocrystals on the surface of KCNO_us ultrathin nanosheets and exhibited enhanced photocatalytic hydrogen generation.Under the irradiation of simulated sunlight,the hydrogen generation rate of resulting optimal Ni₂P/KCNO_us reached up to 72.03?mol·g^-1h^-1,which was about 19.57 times higher than that of single-component KCNO_us.Based on the PL,UV-vis DRS and photo-electrochemical analyses,the possible reasons for the improved photocatalytic activity can be ascribed to reasons that Ni₂P nanocrystals have a low hydrogen evolution overpotential,which can accelerate the surface hydrogen evolution reaction,thus improving the separation efficiency of photogenic carriers and providing the active site of reduction reaction.3.A series of Mo₂C/KCNO_us heterostructures were synthesized by introduction noble-metal-free Mo₂C nanoparticles on the surface of KCNO_us ultrathin nanosheets and exhibited enhanced photocatalytic hydrogen generation.Under the irradiation of xenon light,the hydrogen generation rate of resulting optimal Mo₂C/KCNO_us reached up to 134.26?mol·g^-1h^-1,which was about 8.60 times higher than that of single-component KCNO_us.The apparent quantum efficiency of Mo₂C/KCNO_us was2.23%at 350 nm.Based on the PL,UV-vis DRS and photo-electrochemical analyses,the possible reasons for the enhanced photocatalytic activity put down to the improved light absorption capacity and strong separation efficiency of photoinduced carriers over Mo₂C/KCNO_us heterostructures thanks to the introduction of Mo₂C nanoparticles.