Preparation Of Single Atom Nanocatalyst Composites And Their Photocatalytic Properties For Hydrogen Evolution

In recent years,in order to cope with the crisis of fossil fuel reduction and environmental pollution,photocatalytic hydrogen production technology arises,and in this technical field,photocatalyst preparation has become the top priority.Monatomic catalyst is an excellent choice for photocatalyst preparation due to its advantages of large number of active sites and fast electron transfer rate.However,the development in the field of photocatalysis is limited by the low metal load and poor light absorption capacity of single atom photocatalysts.The most widely used solutions are composites with metal oxides,metal sulfides,or metal-organic frameworks(MOFs),which aim to reduce the band gap and enable more active surface reactions and better photocatalytic hydrogen evolution properties.Therefore,from the perspective of band-gap fitness and electron transfer,in order to get better performance of the photocatalyst,in this paper,CdS/Fe-MOF-525 and CdZnS@Mo single atom composites were respectively synthesized to accelerate the photogenerated carrier and hole transfer and obtain composites with excellent hydrogen production performance.The specific work is as follows:(1)Taking the eight-water chlorine oxidation(ZrOCl2 8H2O)and the organic logger(Fe-TCPP)as the raw material,the Fe-MOF-525 with the Fe-N4 setting structure is obtained through the solvent thermal method.Secondly,CdS/FeMOF-525 composite photocatalyst was synthesized by introducing the synthesized CdS nanoparticles into Fe-MOF-525.The composite catalyst has good photocatalytic hydrogen evolution performance.Experimental results show that the hydrogen evolution performance of CdS/Fe-MOF-525 single atom photocatalyst can reach 3638.6 μmol g-1 h-1 under visible light irradiation.Its excellent photocatalytic hydrogen evolution performance may be due to its synergistic effect,which not only significantly reduces the ratio of electron and hole recombination,but also promotes electron transport,so as to maximize its photocatalytic hydrogen evolution capacity.(2)Mo modified Cd0.5Zn0.5S(CZS@Mo)nanoparticles were constructed by embedding Mo atomic sites into the lattice of CZS nanorods(CZS@Mo)as electron traps.It has excellent photocatalytic hydrogen evolution rate(11.32 mmol g-1 h-1)and remarkable quantum efficiency(41.2%at 420 nm).Experimental and theoretical simulation results show that Mo atoms with high oxidation state lead to mobile charge imbalance in CZS,induce directional photogenerated electron transfer,and effectively inhibit electron-hole recombination.It is not only beneficial to charge separation and directional transfer of photoelectrons,but also greatly improves the photocatalytic efficiency.