Application Of Cobalt Nitride And Nickel Phosphide For Photocatalytic Hydrogen Production

The conversion of solar energy into hydrogen energy by photocatalytic water splitting is an important pathway to solve the current energy problem.In the process of hydrogen production by photocatalytic water splitting,appropriate cocatalysts can serve as catalytic reaction sites to promote photogenerated-carrier transport and separation,thus greatly improve the reactivity.Noble metals are highly efficient cocatalysts for photocatalytic hydrogen production.However,their characteristics of low reserves and high cost limit the large-scale application.Thus,it is extremely important to explore cheap and non-noble metal cocatalysts suitable for photocatalytic water splitting into hydrogen.In recent years,it has been found that first row transition metals and their compounds exhibit good properties as catalysts of water splitting.Among them,the elemental metals,nickel and cobalt,can be used as efficient catalysts for catalytic water splitting into hydrogen.But they are easily oxidized upon exposure to air,which also restricts their practical application.In this thesis,we mainly studied the application of following two transition metal compounds,which can not only serve as efficient cocatalysts,but also possess a good stability in photocatalytic water splitting into hydrogen.1.Co₃NThe Co₃N nanoparticles were facilely synthesized on the surface of semiconductor CdS nanorods.The efficiency of photocatalytic hydrogen production was measured with the Na2S and Na2So3 used as sacrificial agents under visible light irradiation.The results show that the maximum H2 production rate reached?137.33 ?mol h-1 mg-1??>420 nm?and the apparent quantum yield?AQY?was?14.9%??=420 nm?.Photoluminescence?PL?spectra and photocurrent responses indicate that Co3N can help rapidly transfer the photogenerated electrons.2.Ni₂PGraphite-C₃N₄ is a metal-free photocatalyst,which is non-toxic,low-cost.However,its energy conversion efficiency is relatively low due to the recombination of the photogenerated carriers and other issues.We combined the graphite-C3N4 with Ni2P nanoparticles using a facile preparation method and determined the property of photocatalytic water splitting into hydrogen under visible light irradiation.The results show that the efficiency of hydrogen production has greatly improved after the loading of Ni2P nanoparticles.PL spectra show that Ni2P cocatalyst can effectively inhibit the recombination of photogenerated carriers.