| With the continuous development of modern industrial level,energy shortage and environmental pollution have become hot issues all over the world.Semiconductor photocatalysis technology can directly realize the conversion of solar energy to hydrogen energy,which is regarded as an effective way to build a green and sustainable development society.The core of photocatalytic reaction is the highly efficient and stable photocatalytic material.However,the problems of easy recombination of photogenerated carrier and low utilization rate of visible light are common in single-component catalysts,which seriously limit the development of photocatalytic technology.Based on this,this paper takes layered dihydroxides as the research object,and modifies them through morphological regulation and heterojunction construction strategies,so as to optimize the carrier transmission path,increase the number of active sites,improve the utilization efficiency of photogenerated electrons,and finally achieve significantly enhanced photocatalytic activity.The main work contents are as follows:（1）The ZIF-67@CoAl LDH composite photocatalyst was successfully synthesized by hydrothermal method and in situ driven growth technique and applied to photocatalytic hydrogen evolution reaction.The dodecahedral structure of ZIF-67provides sufficient coupling sites for CoAl LDH nanosheets and facilitates the formation of reactive sites.Driven by the internal electric field,the S-scheme heterojunction formed between ZIF-67 and CoAl LDH can effectively promote the separation and migration of photogenerated carriers in the photocatalytic reaction system,and retain a more effective redox potential for the system.In addition,the introduction of CoAl LDH significantly improves the optical response and reduces the electron transport resistance.Hydrophotolytic test showed that under visible light irradiation,the hydrogen production activity of ZIF-67@CoAl LDH material with the optimal coupling ratio could reach 606.26μmol h-1g-1,8.4 times that of ZIF-67(72.46μmol h-1g-1)and 26.1 times of CoAl LDH(23.26μmol h-1g-1).（2）Using Cu MOF octahedron and NiCo LDH nanoflowers as preprecursor,phosphorus atoms were introduced into the reaction system to obtain Cu3P and NiCo P by low temperature phosphating,and Cu MOF and NiCo LDH were phosphating together to obtain Cu3P@NiCo P composite photocatalyst.The phosphating product NiCo P retains the morphologic characteristics of nano-flower,this unique three-dimensional（3D）structure provides enough space for the loading of zero-dimensional（0D）Cu3P nanoparticles,so that the active site of the catalyst can be fully exposed.The photogenic carrier formed by p-n heteroform at the interface between Cu3P and NiCo P creates a more efficient transport path,which greatly promotes the separation of photogenic electrons from photogenic holes.Under the synergistic effect of 0D/3D spatial structure design and p-n heterogeneous structure construction,Cu3P@NiCo P showed significantly enhanced photocatalytic hydrogen evolution activity in EY-sensitized triethanolamine aqueous solution.（3）Two-dimensional graphite-alkyne(GD,CnH2n-2)nanosheets were prepared by cross-coupling method,and CoFe LDH/CuI/GD composite photocatalyst was constructed by solvothermal method.In the composite catalyst,the severe aggregation of CoFe LDH nanorods clusters is effectively improved,which has a positive effect on improving the utilization efficiency of photogenerated carrier.In situ X-ray photoelectron spectroscopy shows that the photogenerated carrier in CoFe LDH/CuI/GD presents a double S-scheme transfer path.Due to the unique photogenic carrier migration mode,the double S-scheme heterojunction catalyst can achieve the spatial separation of oxidation and reduction sites while retaining its own strong redox capacity. |
