2D Ruthenium-Chromium Oxide with Rich Grain Boundaries Boosts Acidic Oxygen Evolution Reaction Kinetics

Abstract

Ruthenium oxide is currently considered as the promising alternative to Ir-based catalysts employed for proton exchange membrane water electrolyzers but still faces the bottlenecks of limited durability and slow kinetics. Herein, a 2D amorphous/crystalline heterophase ac-Cr0.53Ru0.47O2-delta substitutional solid solution with pervasive grain boundaries (GBs) is developed to accelerate the kinetics of acidic oxygen evolution reaction (OER) and extend the long-term stability simultaneously. The ac-Cr0.53Ru0.47O2-delta shows a super stability with a slow degradation rate and a remarkable mass activity of 455 A gRu-1 at 1.6 V vs RHE, which is approximate to 3.6- and 5.9-fold higher than those of synthesized RuO2 and commercial RuO2, respectively. The strong interaction of Cr-O-Ru local units in synergy with the specific 2D structural characteristics of ac-Cr0.53Ru0.47O2-delta dominates its enhanced stability. Meanwhile, high-density GBs and the shortened Ru-O bonds tailored by amorphous/crystalline structure and Cr-O-Ru interaction regulate the adsorption and desorption rates of oxygen intermediates, thus accelerating the overall acidic OER kinetics. A 2D amorphous/crystalline ac-Cr0.53Ru0.47O2-delta exhibits superior activity for the OER in an acid medium, in which high-density grain boundaries and tailored RuO bonds synergistically facilitate the adsorption and desorption of oxygen intermediates, thus significantly boosting the catalytic kinetics and durability. image