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

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.