Synthesis And Photocatalysis Of Single Atom/nanoparticle@g-C₃N₄ Composite Catalysis System

The energy crisis and the increasingly serious environmental problems need to be solved urgently.The conversion and utilization of solar energy is expected to be an effective way to solve the energy and environmental problems.Graphite phase carbon nitride(g-C₃N₄)as a rich,cheap,clean and friendly semiconductor material has attracted wide attention.However,the pure g-C₃N₄ has such defects as high photogenerated holes and electron recombination rate,large internal resistance and narrow light absorption range,which makes its photocatalytic efficiency low.In order to further improve the efficiency of light energy conversion,this paper focuses on the synthesis of single atom/nanoparticle@g-C₃N₄ composite catalytic system to improve the photocatalytic activity.The details showed as below:1.Z-type heterojunction materials were constructed to realize efficient photocatalytic conversion of CO₂ to methanol in pure water.In order to improve the light absorption range of g-C₃N₄ and accelerate the separation of photogenerated electrons and holes,the composite catalytic material was constructed by Cu₂O and g-C₃N₄ with narrow band gap and wide light absorption range.This work developed a simple method for in situ synthesis of Cu₂O nanocrystal crystals on g-C₃N₄,constructed Cu₂O@g-C₃N₄ Z-type heterojunction,and solved the problems of low photocatalytic CO₂ reduction activity of g-C₃N₄ and photoetching of Cu₂O.Using water as proton source and Cu₂O@g-C₃N₄ Z-type heterojunction material as photocatalyst,the efficient photocatalytic conversion of CO₂ to methanol was realized in pure water.It provides a simple and effective synthetic strategy for the construction of Z-type heterojunctions.2.Single-atom modification of g-C₃N₄ for high efficiency photocatalytic hydrogen production.g-C₃N₄ is a good carrier material in photocatalytic hydrogen production system.Ruthenium nanoparticles(N-Ru@g-C₃N₄)and ruthenium monoatom(S-Ru@g-C₃N₄)supported on g-C₃N₄ were synthesized by photoinduced deposition in this work.Ru was loaded on g-C₃N₄ as a single atom by transmission electron microscope with a probe corrector.Driven by visible light,the hydrogen production efficiency of S-Ru@g-C₃N₄ is as high as 916.5?mol g^-1 h^-1,which is better than N-Ru@g-C₃N₄,which is 810?mol g^-(16)h^-(16).The results show that the preparation of S-Ru@g-C₃N₄ catalyst can not only greatly improve the metal utilization rate,but also greatly improve the light energy conversion efficiency.