Preparation of gold nanostars covered with platinum particles and their photoelectrocatalysis properties.

The hydrogen evolution reaction (HER) must use a catalyst to reduce the overpotential and accelerate the chemical reaction of the electrolysis process. Pt stands out because of its very good catalytic properties. However, the extremely low content of Pt in the Earth's crust and the high price of Pt severely limit the large-scale use of this precious metal. In order to reduce the use of Pt and enhance catalytic activity, we designed a composite structure by combining the plasmon effect characteristics of Au with Pt particles. In this work, we investigated the synthesis and growth mechanism of Au@Pt nanostars with gold nanostars (Au NS) as the core, and explored the application efficiency of Au@Pt nanostars in photocatalysis. The Au NS were produced by a "one-step synthesis", and the Au@Pt nanostars were synthesized by growing Pt on the nanostar surface. More branched Au NS formed catalysts with Pt clusters for metal ionization enhancement. The catalytic activity of the structure was increased by the presence of Pt. The synergistic advantages of the heterogeneous composite nanostructures mean the structures have high photoelectrocatalysis activity at the edge and corner positions. Benefiting from the synergistic effect and the plasmon-induced accelerated molecular transformations, the Au@Pt nanostars manifest outstanding plasmon-enhanced electrochemical activity toward the HER with a low overpotential of 23.08 mV for achieving the current density of 10 mA cm⁻², which surpasses the commercial Pt/C catalyst. At the same time, the Au NS also exhibit excellent photocatalytic performance with a smaller initial overpotential (ΔV = 9.03 mV) than that in the absence of light. This shows that the study of this structure can be used for the development and application of new energy and hydrogen energy. [ABSTRACT FROM AUTHOR]