Preparation Of Au/TiO₂ Plasmonic Composite Photocatalysts With Enhanced Photocatalytic Hydrogen Deneration Activity

The production of chemical fuels by solar energy conversion has been considered as one of the major strategies for solving the global energy problem.Since the pioneering report by Fujishima and Honda on photoelectrochemical water splitting on a TiO₂ electrode,this photocatalytic process has attracted a lot of attention and appears to be a promising strategy for clean,low-cost,and environmentally friendly production of H₂ by utilizing solar energy.TiO₂ as a wide band gap semiconductor material,has been widely studied in the field of photocatalysis due to its excellent properties.However,pure TiO₂ can only be active in the ultraviolet?UV?that accounts for only 4%of the entire solar spectrum,and photogenerated electrons and holes are easy to be recombined.Therefore,great efforts have been done to improve its photocatalytic activity.Among the noble metals,gold has attracted significant interest.The application of gold nanoparticles as a catalyst has increased dramatically in the past twenty years.The local surface plasmon resonance effect produced by its electronic resonance enhanced the absorption of visible light by Au.Based on this optical properties of gold,we have designed the Au/TiO₂ plasma composite photocatalyst to catalyze the hydrolysis of hydrogen to produce hydrogen.The effect of the size of Au nanoparticles on the hydrogen production activity of Au/TiO₂ plasma composite photocatalyst was studied.First,Au/TiO₂/MoS₂ plasmonic composite photocatalysts were synthesized via deposition-precipitation with urea.The photocatalytic activities of the prepared samples were evaluated by performing hydrogen production experiments under Xe lamp irradiation with a 10%??,volume fraction?glycerol aqueous solution as the sacrificial agent.The results showed that the optimal content of MoS₂ in the Au/TiO₂/MoS₂ composite is 0.1%?w,mass fraction?and the corresponding H₂production rate was 708.85?mol?h^-1,which was almost 11 times higher than that of TM6.0 with the strongest photocatalytic activity in the all binary TiO₂/MoS₂composites.The enhanced photocatalytic activity of the ternary Au/TiO₂/MoS₂composites is mainly due to the surface plasmon resonance of the supported Au nanoparticles absorbed on the TiO₂/MoS₂ layered composite,which show an intense absorption maximum centered around 550–560 nm and induce the photoexcitation of electrons.Meanwhile,the electrons excited by surface plasmon resonance of Au could be injected into the conduction band of TiO₂,and they were then transferred to the edges of MoS₂ for catalyzing the production of H₂.Second,Au/TiO₂ plasmonic composite photocatalysts were synthesized via deposition-precipitation with urea and Light reduction method.The photocatalytic activities of the prepared samples were evaluated by performing hydrogen production experiments under Xe lamp irradiation with a 10%??,volume fraction?glycerol aqueous solution as the sacrificial agent.The results showed that when the size of gold nanoparticles is 5 nm,the composite sample AT-150 has the highest photocatalytic hydrogen production activity,and the corresponding H₂ production rate is 234.43?mol/h.It was found that the plasmon resonance effect and hydrogen production activity of small gold nanoparticles under visible light irradiation were weak,but under ultraviolet light irradiation,they could promote the effective separation of photogenerated electron-hole pairs.At the same time,as the active site of hydrogen production,the photocatalytic activity of hydrogen production was improved effectively.