Facile One-Pot Synthesis of a PtRh Alloy Decorated on Ag Nanocubes as a Trimetallic Core-Shell Catalyst for Boosting Methanol Oxidation Reaction

The development of highly active and stable catalysts is a critical challenge which affects the practical application of the direct methanol fuel cells. Alloying Pt with other metals is an effective strategy to form the bimetallic or trimetallic catalysts, which not only decreases the consumption of Pt but also optimizes the electronic structure of Pt, in turn enhancing the catalytic activity. Herein, we use a facile one-pot solvothermal reduction method to synthesize Ag nanocubes (NCs) enclosed by PtRh nanoparticles as a trimetallic Ag@PtRhAg NC core-shell catalyst toward methanol oxidation reaction (MOR). Notably, the core-shell structure is formed because of the presence of N,N-dimethylacetamide, which promotes the preferential reduction of Ag by reducing the reduction potential of Ag atoms. Meanwhile, the bromide ions originating from cetyltrimethylammonium bromide controlled the growth of the cubic morphology. Benefiting from the pleated exterior providing more active sites and the synergistic effect between Pt, Rh, and Ag, the mass and specific activities of Ag@PtRhAg NCs are 4.22 and 3.78 times higher than those of commercial Pt/C, respectively. More impressively, because of the better CO tolerance, Ag@PtRhAg NCs display strengthened durability by maintaining 84.9% mass activity after 1000 MOR cycles compared to the initial value. The present work provides a one-step strategy to synthesize a core-shell nanostructure catalyst for enhancing the MOR activity.