Local tetragonal distortion of Pt alloy catalysts for enhanced oxygen reduction reaction efficiency

Platinum-based alloy nanoparticles are the most attractive catalysts for the oxygen reduction reaction at present, but an in-depth understanding of the relationship between their short-range structural information and catalytic performance is still lacking. Herein, we present a synthetic strategy that uses transition-metal oxide-assisted thermal diffusion. PtCo/C catalysts with localized tetragonal distortion were obtained by controlling the thermal diffusion process of transition-metal elements. This localized structural distortion induced a significant strain effect on the nanoparticle surface, which further shortened the length of the Pt-Pt bond, improved the electronic state of the Pt surface, and enhanced the performance of the catalyst. PtCo/C catalysts with special short-range structures achieved excellent mass activity (2.27 A mgPt-1) and specific activity (3.34 A cm-2). In addition, the localized tetragonal distortion-induced surface compression of the Pt skin improved the stability of the catalyst. The mass activity decreased by only 13% after 30,000 cycles. Enhanced catalyst activity and excellent durability have also been demonstrated in the proton exchange membrane fuel cell configuration. This study provides valuable insights into the development of advanced Pt-based nanocatalysts and paves the way for reducing noble-metal loading and increasing the catalytic activity and catalyst stability. Through reasonable control of the thermal diffusion process and strategic manipulation of the short-range local structure of the alloy catalyst, the synthesized Pt-Co/C catalyst shows a special core-shell structure and local tetragonal distortion, which modulate the alloy surfaces to produce stronger compressive strains. The catalytic activity and long-term durability of the catalysts are significantly enhanced by the structure-induced surface compressive strain. image