Shape effects of Pt nanoparticles on hydrogen production via Pt/CdS photocatalysts under visible light

The shape effects of Pt cocatalysts on the photocatalytic activity of Pt/CdS for hydrogen production were investigated for the first time. Nano-cubic and nano-spherical Pt particles were prepared via a shape-and-size-controlled technology and loaded onto a CdS semiconductor photocatalyst for visible light photocatalytic hydrogen production from an aqueous ammonium sulfite solution. Unlike conventional photodeposition and impregnation methods, shape-controlled synthesis is able to produce cubic Pt cocatalysts with tunable sizes. Pt nanocube loaded Pt/CdS photocatalysts show strong shape enhanced photocatalytic activity compared to those of Pt nanospherical particle loaded Pt/CdS photocatalysts. With the same Pt loading and Pt particle size the efficiencies of Pt nanocube loaded Pt/CdS catalysts are 52% and 31% higher than those of Pt nanosphere loaded Pt/CdS photocatalysts at 5.7 nm and 4.0 nm, respectively. In comparison with Pt/CdS photocatalysts prepared via photodeposition, more than 25% efficiency improvement has been achieved with the Pt nanocube loaded Pt/CdS photocatalysts. The electrochemical characterization of Pt nanoparticles revealed that photocatalytic activities of Pt/CdS photocatalysts rely on both the shape and size of the Pt particles. The higher the electrocatalytic activity of the Pt nanoparticles, the higher the efficiency of photocatalytic hydrogen evolution.