Laser-Irradiation-Induced Melting and Reduction Reaction for the Formation of Pt-Based Bimetallic Alloy Particles in Liquids.

Laser melting in liquids (LML) is one of the most effective methods to prepare bimetallic alloys; however, despite being an ongoing focus of research, the process involved in the formation of such species remains ambiguous. In this paper, we prepared two types of Pt-based bimetallic alloys by LML, including Pt-Au alloys and Pt-iron group metal (iM=Fe/Co/Ni) alloys, and investigated the corresponding mechanisms of alloying process. Detailed component and structural characterizations indicate that laser irradiation induced a quite rapid formation process (not exceeding 10 s) of Pt-Au alloy nanospheres, and the crystalline structures of Pt-Au alloys is determined by the monometallic constituents with higher content. For Pt-iM alloys, we provide direct evidence to support the conclusion that FeO /CoO /NiO colloids can be reduced to elementary Fe/Co/Ni particles by ethanol molecules during laser irradiation, which then react with Pt colloids to form Pt-iM sub-microspheres. These results demonstrate that LML provides an optional route to prepare Pt-based bimetallic alloy particles with tunable size, components, and crystalline phase, which should have promising applications in biological and catalysis studies.