Preparation of ZnO Nanoparticles and Photocatalytic H₂ Production Activity from Different Sacrificial Reagent Solutions

ZnO nanoparticles were synthesized via a direct precipitation method followed by a hetero-geneous azeotropic distillation and calcination processes, and then characterized by X-ray power diffraction, scanning electron microscopy, transmission electron microscopy, and ni-trogen adsorption-desorption measurement. The effects of Pt-loading amount, calcination temperature, and sacrificial reagents on the photocatalytic H₂ evolution efficiency from the present ZnO suspension were investigated. The experimental results indicate that ZnO nanoparticles calcined at 400 oC exhibit the best photoactivity for the H₂ production in comparison with the samples calcined at 300 and 500 oC, and the photocatalytic H₂ pro-duction efficiency from a methanol solution is much higher than that from a triethanolamine solution. It can be ascribed to the oxidization of methanol also contributes to the H2 produc-tion during the photochemical reaction process. Moreover, the photocatalytic mechanism for the H₂ production from the present ZnO suspension system containing methanol solution is also discussed in detail.