A Facile and Green Eutectic Salt-Mediated Pyrolysis Strategy to Synthesize Hollow PtNi Alloy Nanocubes for Oxygen Reduction Reaction

The preparation of low-cost, high-activity, and high-stability platinum (Pt)-based oxygen reduction reaction (ORR) catalysts is the key to the large-scale commercial application of proton exchange membrane fuel cells. Herein, we designed a facile synthesis strategy to achieve direct transformation of solid Pt nanoparticles into hollow PtNi alloy nanocubes through a eutectic salt-mediated pyrolysis strategy and nanoscale Kirkendall effect. This distinctive hollow structure makes the inner and exterior spaces easy to access, which would expose additional active sites and a high active surface area. Accordingly, the as-synthesized Pt1Ni8@NC sample, with the moderate Ni feeding content, exhibits an improved ORR activity and stability with respect to a pristine Pt/C catalyst. Such improvement in ORR performance is mainly caused by the moderate surface compositions, high surface area, and well-designed nanostructure. Indeed, this facile surfactant- and template-free synthetic strategy in our work can be extended for fabricating electrocatalysts with a similar hollow cubic structure.