Modification Of Transition Metal Phosphide And Its Mechanism For Enhancing Photocatalytic Hydrogen Evolution Of Graphite Carbon Nitride

Hydrogen energy is an ideal alternative energy to solve the energy crisis and envi-ronmental problems.The photocatalytic decomposition of water technology provides an effective way to convert solar energy into clean and sustainable hydrogen energy.Graph-ite carbon nitride（g-C₃N₄）has the advantages of low cost,pollution-free,appropriate band gap and excellent chemical stability,and is considered to be a promising photocata-lytic hydrogen production material.Transition metal phosphides with metallic properties play a prominent role in the field of photocatalytic hydrogen production.The modifica-tion of transition metal phosphides can effectively promote the charge transfer efficiency of g-C₃N₄ and improve the photocatalytic hydrogen production performance.In this pro-ject,the research status of surface modification of g-C₃N₄ photocatalysts in the field of photocatalytic hydrogen production in recent years was first summarized.Then,Mo based compounds were introduced into transition metal phosphides to modify g-C₃N₄,solving the inherent defects of g-C₃N₄ photocatalyst materials and improving its photo-catalytic hydrogen production performance.The specific research content is as follows:1)To address the issues of low carrier separation efficiency and high hydrogen evo-lution overpotential during the water decomposition process caused by insufficient charge transfer driving force in g-C₃N₄,we propose introducing a metal molybdenum modified Co P co-catalyst and synthesizing an efficient in situ method Mo-Co P@g-C₃N₄ Hydrogen production photocatalyst.The introduction of metal Mo increases the functional differ-ence between g-C₃N₄ and the co-catalyst Co P,effectively enhancing the Schottky effect,thereby improving the separation and migration efficiency of photo excited charges;At the same time,it reduces the hydrogen evolution overpotential on the surface of Co P,ef-fectively improving the photocatalytic hydrogen evolution performance of g-C₃N₄.2)In order to further improve the conductivity of transition metal phosphides,re-duce the overpotential of hydrogen evolution reaction,and construct a more efficient Schottky effect,an appropriate amount of Mo O₂ with platinum like properties was intro-duced onto Ni₂P,and a rod-shaped Mo O₂/Ni₂P co catalyst was synthesized by hydro-thermal method.It can effectively enhance the adsorption of H atoms on the surface of Ni₂P,increase the functional difference between g-C₃N₄ and the co-catalyst,reduce the hydrogen production overpotential,and thereby enhance the entire process of charge transfer,thereby greatly improving the photocatalytic hydrogen evolution performance of g-C₃N₄.3)The co-catalysts with different morphologies also have a certain impact on the photocatalytic hydrogen production rate of g-C₃N₄.We further designed and synthesized a Ni₂P-Mo O₂ co-catalyst with a sheet-like structure,forming a two-dimensional interface with the sheet-like g-C₃N₄ to increase the contact area between the photocatalyst and the co-catalyst.Compared to the rod like structure of Mo O₂/Ni₂P co-catalyst,this co-catalyst can achieve close contact with the main catalyst,making electron migration smoother,thus improving the photocatalytic hydrogen production performance.