Tungsten as “Adhesive” in Pt₂CuW_0.25 Ternary Alloy for Highly Durable Oxygen Reduction Electrocatalysis

Pt-based alloy nanocrystals have shown great success in oxygen reduction electrocatalysis owing to their unique surface and electronic structures. However, they suffer from severe stability issues due to the dissolution of non-noble metal elements, leading to the “trade-off” between activity and stability. In this work, targeting the stability issue of a Pt_xCu_y-based alloy, Pt₂CuW_0.25 ternary alloy nanoparticles are synthesized by thermal reduction strategy based on wet-chemical method using W(CO)₆ as a reductant. Apart from the competitive activity, the obtained Pt₂CuW_0.25/C shows remarkable stability, whereby the area specific activity and mass activity maintain 89.5% and 95.9% of the initial values, respectively, after 30 000 cycles of accelerated polarization between 0.6 and 1.1 V (vs reversible hydrogen electrode). By using vacancy formation energy of surface Pt as the descriptor, it is found that the enhanced stability of Pt₂CuW_0.25/C originates mainly from the stronger bonding between W and Pt/Cu atoms, acting as an “adhesive” to stabilize the atoms from dissolution, which is further verified by chemical stability experiments. This work demonstrates a rational design strategy for ternary alloy nano-electrocatalyst that has high thermodynamic stability while maintaining high activity by employing high-melting-point metal.