Preparation And Performance Of Nano-goldplasmonic Composite Photocatalyst Forhydrogen Evolution From Water Splitting

The hydrogen energy obtained via a solar photocatalytic decomposition of water to hydrogen technology has attracted much attention on account of its high energy and environmental friendliness characteristics.Thereinto,the choice of photocatalyst is one of the key elements to solar photocatalytic decomposition of water to hydrogen technology.At present,the photocatalyst cannot be widely applied to the actual industrial production,due to the low photocatalytic activity efficiency of semiconductor photocatalyst for hydrogen evolution through photocatalytic water splitting,easy electron-hole recombination,and poor light stability.Since plasma was applied to visible-light-responsive photocatalysts in the early time,and it had open a novel research direction using noble metal plasmon resonance to improve photocatalytic activity.In this paper,we have synthesized three kinds of plasma photocatalysts obtained by combining noble metal nanoparticles with semiconductor photocatalysts via soft chemical synthetic methods,and studied the photocatalytic hydrogen production performance in detail.The specific research content and results are as follows:1.Nano Au-g-C₃N₄ plasma photocatalyst was prepared by a sol-gel method.The XRD results reveal that Nano Au-g-C₃N₄ present good crystal phase and good purity can be obtained at 550 ^oC.The TEM results show that the gold nanoparticles are formed by approximate spherical shapes in the size of around 5-15 nm,which is evenly distributed in g-C₃N₄.STEM-EDS data shows that there are only three elements of Au,C,and N in the sample.The XPS spectrum shows that exists in gold elemental form and binds tightly to g-C₃N₄.Nano Au-g-C₃N₄ showed obvious plasmon resonance absorption peaks of gold nanoparticles at 521 nm with a small red shift.Under the excitation of visible light,Nano Au-g-C₃N₄ presents good photocatalytic activity for water-decomposition.The results reveal that the photocurrent response is maximum and the photocatalytic hydrogen production activity is the highest which is 1.86 times that of pure g-C₃N₄,when the content of gold nanoparticles is 1 wt%.2.Nano Au/SrTiO₃ plasma photocatalyst was synthesized via simple sol-gel method.The research results show that SrTiO₃ and gold nanoparticles are formed in the size of around 100-200 nm and 20 nm,respectively.Pure SrTiO₃ does not showing photocatalytic activity under visible light,while Nano Au/SrTiO₃ presents a characteristic absorption of gold nanoparticles which is due to the plasma resonance effect of gold nanoparticles.The XPS characterization indicates that the Au nanoparticles are in the form of elemental gold.The fluorescence spectra and photocurrent measurements show that gold nanoparticles can reduce the photoelectron-hole recombination in Nano Au/SrTiO₃.Under visible light,Nano Au/SrTiO₃ presents good photocatalytic activity for water-decomposition.The results reveal that the photocurrent response is maximum and the photocatalytic hydrogen production activity is the highest which is estimated to be around 64.23?mol·h^-1·g^-1,when the content of gold nanoparticles is 1.36 wt%.3.A series of solid solution Mn_xCd_1-xS were prepared by a hydrothermal process.Mn_xCd_1-xS solid solution with best photocatalytic hydrogen production activity has been realized by adjusting the ratio between Mn and Cd elements,and then Nano Au-Mn_0.8Cd_0.2S plasma photocatalyst with varying content of gold nanoparticles were prepared by photodeposition.The results show that when x=0.8,the Mn_0.8Cd_0.2S solid solution are mixed phases,namely,the cubic phase?-MnS,the hexagonal phase?-MnS and the cubic phase CdS.In addition,Mn_0.8Cd_0.2S presents good photocatalytic activity for water-decomposition.Nano Au-Mn_0.8Cd_0.2S has a stronger light absorption in the visible region,which is due to the plasma resonance effect of gold nanoparticles.The photocurrent density is the highest,when the mass ratio of loaded gold is 4%.At the same time,the rate of photocatalytic hydrogen production under visible light is1108?mol·h^-1·g^-1,which is 2.7 times higher than that of pure Mn_0.8Cd_0.2S.