Breaking Surface Atomic Monogeneity of Rh₂P Nanocatalysts by Defect‐Derived Phosphorus Vacancies for Efficient Alkaline Hydrogen Oxidation

Abstract

Breaking atomic monogeneity of catalyst surfaces is promising for constructing synergistic active centers to cope with complex multi-step catalytic reactions. Here, we report a defect-derived strategy for creating surface phosphorous vacancies (P-vacancies) on nanometric Rh₂ P electrocatalysts toward drastically boosted electrocatalysis for alkaline hydrogen oxidation reaction (HOR). This strategy disrupts the monogeneity and atomic regularity of the thermodynamically stable P-terminated surfaces. Density functional theory calculations initially verify that the competitive adsorption behavior of H_ad and OH_ad on perfect P-terminated Rh₂ P{200} facets (p-Rh₂ P) can be bypassed on defective Rh₂ P{200} surfaces (d-Rh₂ P). The P-vacancies enable the exposure of sub-surface Rh atoms to act as exclusive H adsorption sites. Therein, the H_ad cooperates with the OH_ad on the peripheral P-sites to effectively accelerate the alkaline HOR. Defective Rh₂ P nanowires (d-Rh₂ P NWs) and perfect Rh₂ P nanocubes (p-Rh₂ P NCs) are then elaborately synthesized to experimentally represent the d-Rh₂ P and p-Rh₂ P catalytic surfaces. As expected, the P-vacancy-enriched d-Rh₂ P NWs catalyst exhibits extremely high catalytic activity and outstanding CO tolerance for alkaline HOR electrocatalysis, attaining 5.7 and 14.3 times mass activity that of p-Rh₂ P NCs and commercial Pt/C, respectively. This work sheds light on breaking the surface atomic monogeneity for the development of efficient heterogeneous catalysts.