| Fabricating efficient,stable and inexpensive photocatalytic H2 production system is one of the feasible way to solve the current energy problems.Although the commonly used precious metal Pt as co-catalyst has some advantages such as stable and high efficiency,its limited resources,high cost and catalytic the reverse reaction of the H2 production reaction limit its large-scale application.Therefore,developing new,efficient,stable and inexpensive non-noble metal co-catalyst loaded semiconductors and their photocatalytic H2 production system is an urgent topic.Herein,preparation of Cu,Ni etc.non-noble metal co-catalyst loaded semiconductors and their photocatalytic H2 production properties were investigated.The main research contents and conclusions were summarized as follows:1.Brookite TiO2 with size of-50 nm were hydrothermally synthesized by using TiCl4 as titanium source,urea and sodium lactate as regulator,and then Cu nanoclusters with size of ca.1-2 nm were deposited on those BTN particles' surface to obtain a series of Cu/BTN nanocomposites.Under the optimized photoreaction conditions,the H2 production activity of Cu/BTN with an optimal Cu-loading amount is similar to that of Cu/P25,and is ca.77%of that of Pt/BTN.Those Cu nanoclusters with high specific surface area and dispersion can shorten the photogenerated charge transport pathway and promote the charge separation,and thus causing the significantly enhanced H2 production activity.The present results can not only promote the development of non-noble metal co-catalyst instead of the precious metal,but also provide new idea for fabricating brookite TiO2-based photocatalysts with low cost and high efficiency.2.Metal Ni nanoclusters were deposited on the above BTN particles' surface to obtain a series of Ni/BTN nanocomposites through a chemical reduction process.Since the Ni nanoclusters loaded on BTN surface were more easily oxidized than Cu nanoclusters,the effects of the Ni-loading amount and its oxidation state on the spectral absorption,photocatalytic H2 production activity and stability and the related mechanisms were mainly investigated.The results showed that the Ni nanoclusters with size of ca.1-2 nm co-exist with more NiO nanoclusters to form NiOx/TiO2-like nanocomposite.Because the electron capture capacity of NiO was much lower than that of metallic Ni,the coexistence of NiO was detrimental to the improvement of photocatalytic H2 production activity and stability.These results provide some reference for the synthesis and performance improvement of Ni-based co-catalyst in the future.3.For inhibiting the oxidation of the metallic Ni co-catalyst,carbon layer was coated on Ni nanoparticle to form a novel carbon coated nickel(Ni@C)co-catalyst.A series of Ni@C/Cd0.8Zn0.2S nanocomposites were synthesized through a one-pot hydrothermal method by using Ni@C,Cd(CH3COO)2 and Zn(CH3COO)2 as raw materials,thioacetamide(TAA)as sulfur source,and sodium dodecyl sulfate(SDS)as the shape modifier,respectively.Under the optimized photoreaction conditions,the photocatalytic H2 production activity of Ni@C/Cd0.8Zn0.2S was not only higher than that of Pt/Cd0.8Zn0.2S,but also was-3.10 times of that of the single Cd0.8Zn0.2S.Further investigation results indicated that the improved photocatalytic H2 production activity was mainly attributed to synergistic effect of Ni@C,in which the metal Ni core served as co-catalyst,while the carbon layer as protection coating and electron conductor to improve the photochemical stability of the Ni co-catalyst.In addition,the carbon layer acted as the support of Cdo.8Zno.2S nanoparticles,which can easily accept the conduction band electrons to promote the photogenerated charge separation of Cd0.8Zn0.2S,and thus causing the enhanced H2 production activity.The above results demonstrate that Ni@C is a better and cheaper co-catalyst than the noble metal Pt,and pave a new way to improve the performance of non-noble metal co-catalyst. |
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