Preparation And Performance Of Plasmonic Photocatalyst For Hydrogen Evolution From Water Splitting

Recently, a great deal of attention has been paid to the utilization of solar energy for the production of hydrogen from water due to the global environmental pollution and energy shortage. How to use solar for hydrogen evolution efficiently is a research hotspot, one of the keys to this problem is to explore photocatalysts with high efficiency.More than 40 years have passed, since TiO2 had been explored as a photocatalyst for water splitting by A. Fujisima and K. Honda. Much works have been done on exploring new photocatalysts for water splitting hydrogen evolution. Unfortunately, up to now, the photocatalytic efficiency of the current photocatalyst for hydrogen evolution from water splitting is still low, and they could not meet the requirements for actual industrial production. Therefore, it is very important to explore novel photocatalysts with high activity for hydrogen evolution from water splitting using solar energy. It is possible to improve the photocatalytic activities of photocatalysts by combining noble metal nanoparticles with semiconductor catalysts of utilizing their surface plasma resonance effect.In this paper, several of plasmonic photocatalysts with response to visible light with high photocatalytic activity were prepared by combining gold nanoparticles with semiconductor materials. The detailed research contents are shown as follows:1. Nano Au/Ta2O5 plasmonic photocatalysts were prepared via a Pechini-type sol-gel process, then Nano Au/Ta3N5 plasmonic photocatalysts were obtained after high temperature nitriding. The experimental results show that Ta2O5 and Nano Au/Ta2O5 were prepared successfully under 750 oC calcination, and further nitridating Ta2O5 and Nano Au/Ta2O5 composite samples in ammonia flow at 750 oC yielded Ta3N5 and Nano Au/Ta3N5 composite samples. The gold nanoparticles in size of around 15 ~ 20 nm were distributed in Ta2O5 and Ta3N5 homogeneously to get Nano Au/Ta2O5 and Nano Au/Ta3N5 composites. Blank Ta2O5 absorbs only UV light, after Au nanoparticles were embedded in Ta2O5, Nano Au/Ta2O5 has good light absorption in the visible area and shows high photocatalytic activity of hydrogen evolution with visible light irradiation.Compared to the blank Ta3N5, the light absorption intensity of Nano Au/Ta3N5 increased a little bit, and its photocatalytic hydrogen evolution activity also has a certain improvement.2. Monodisperse SiO2@Nano Au@Ta2O5 and SiO2@Nano Au@Ta3N5 plasmonic photocatalysts with core-shell structures were prepared by combining a variety ofsimple methods, such as Stober process, standard citrate reduction method, and sol-gel process. The results indicate that Ta2O5 and Ta3N5 were coated on the SiO2@Nano Au successfully and the products have core-shell structures indeed. The thickness of the shell of Ta2O5/Ta3N5 is about 50 nm. Blank Ta2O5 absorbs only UV light, the light absorption of SiO2@Nano Au@Ta2O5 extended to visible light after decorated with the Au nanoparticles and showed well photocatalytic hydrogen production activity under visible light irradiation. Compared to the blank Ta3N5, the light absorption intensity of SiO2@Nano Au@Ta3N5 increased, and its photocatalytic hydrogen production performance also got a certain ascend.3. Nano Au-ZnTiO3 composite plasmonic photocatalyst were prepared by a sol-gel process combining with photodeposition method. The results indicate that ZnTiO3 sintered at 900 oC shows a mixed phase composed of cubic and hexagonal with a approximately spherical morphology in the size range of 50 ~ 100 nm. An intense absorption band centered at 525 nm of Nano Au-ZnTiO3 can be observed in visible light region due to surface plasma resonance effect of Au nanoparticles. Under the irradiation of visible light, the Nano Au-ZnTiO3 plasmonic photocatalyst shows excellent photocatalytic activity for hydrogen evolution from water splitting.