The Design And Synthesis Of 2D MOF And Derived Materials In Photocatalysis And Electrocatalysis Hydrogen Generation

Since the discovery of graphene with excellent properties,two-dimensional(2D)nanomaterials have attracted extensive research due to their unique physical and chemical properties,such as large specific surface area,excellent optical transparency,and excellent electrical and thermal conductivities.Metal-organic frameworks are formed by the coordination of metal ions and organic ligands,which have high specific surface area and structural tunability.They have been widely used in energy storage,molecular separation,sensing,drug delivery,and photoelectric catalysis.So far,scientists have developed a variety of methods to synthesize MOF,including threedimensional bulk crystals and small nanoparticles,with specific sizes,shapes,and compositions.However,current research work on MOF materials is mainly devoted to bulk MOF crystals,but the synthesis of 0D MOF nanoparticles and 1D MOF nanorods/nanowires as well as 2D MOF nanosheets remains a great challenge.Because it is necessary to suppress the growth of MOF crystals so that they can only reach the nanoscale in the vertical direction without affecting the growth of the other two directions.As a kind of two-dimensional nanomaterials,two-dimensional MOF nanosheets are expected to exhibit excellent properties in the fields of energy storage,molecular separation,sensing,drug delivery,and optoelectronic catalysis.Therefore,as an emerging 2D nanomaterial,2D MOF provide new opportunities for scientific research.In this paper,starting from the design and synthesis of two-dimensional MOF and its derivatives,two two-dimensional MOF-derived catalysts were designed and prepared,and their performances in photocatalytic and electrocatalytic reactions were mainly studied.In this paper,we first synthesized ZIF-67@ZIF-8 with a core-shell structure,and then utilized the different stabilities of ZIF-67 and ZIF-8 to directionally dissolve the inner ZIF-67 by a hydrothermal method,and then burst the outer ZIF-8.The twodimensional Zn/Co-ZIF is obtained from the shell layer,and finally the catalyst Zn/CoZIF-P-400 is obtained by carbonization and phosphating.By controlling the feeding ratio of different metal salts,catalysts with different Zn/Co ratios can be synthesized.Finally,the transition metal phosphide Co P is obtained by phosphating,which can replace the widely used noble metal catalysts for hydrogen evolution reaction.1:2Zn/Co-ZIF-P-400 shows excellent catalytic performance in the electrolysis of water for hydrogen production,and has good stability.Secondly,by hydrothermal treatment of Zn-MOF-74 with urea,two-dimensional sheet-stacked ZnO was synthesized by thermal decomposition of urea,and then ZnO was compounded with Cd S to obtain the final catalyst X-Cd S/ZnO.Among them,ZnO and Cd S are both photocatalysts with excellent performance,so X-Cd S/ZnO was used for photocatalytic degradation of dyes and photocatalytic hydrogen evolution reaction.The recombination of ZnO and Cd S inhibits the recombination rate of photogenerated electrons and holes,broadens the absorption range of the catalyst and light,and thus greatly enhances the catalytic performance of the catalyst.In addition,the catalyst has high stability,and the catalytic effect is not significantly reduced after five repeated experiments.