Oxygen Reduction Reaction over PtFeM (M = Mo, V, W) Alloy Electrocatalysts: Role of the Compressive Strain Effect on Pt

Abstract

The high level loading requirement of platinum and the sluggish oxygen reduction kinetics - catalyzed by platinum-based electrocatalysts - create major bottlenecks for cost-effective application of fuel cell technology. Herein, ternary PtFeM (M = Mo, V, W) alloy electrocatalysts with different levels of compressive strain on Pt were systematically prepared using the method of impregnation-reduction, post-treated at high temperatures. The physicochemical characterization displays that these elements (Fe, Mo, V, and W) are crucial for inducing a compressive strain effect on Pt and improving the oxygen reduction activity. In all the as-prepared electrocatalysts, a remarkable enhancement of ∼20-fold in mass activity at 0.9 V, with respect to commercial Pt/C, is witnessed on Pt25Fe70Mo5/C that possesses the moderately compressive strain effect on Pt and the suitable electronic ligands. After accelerated testing (30k cycles of cyclic voltammetry), Pt25Fe70Mo5/C exhibits ∼threefold activity compared to pristine Pt/C. The reasons could be the aggregation of electrocatalysts during electrochemical testing as well as the dissolution of metal elements in acidic solution, especially in electrochemical environmental conditions. Additional work is needed to enhance the stability such as coating metal nanoparticles with ultrathin material that possesses antiacidic and antioxidant properties and to balance the catalytic stability and activity to meet the requirements of practical application. Copyright © 2019 American Chemical Society.