Breaking Surface Atomic Monogeneity of Rh P 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 Rh 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 and OH on perfect P-terminated Rh P{200} facets (p-Rh P) can be bypassed on defective Rh P{200} surfaces (d-Rh P). The P-vacancies enable the exposure of sub-surface Rh atoms to act as exclusive H adsorption sites. Therein, the H cooperates with the OH on the peripheral P-sites to effectively accelerate the alkaline HOR. Defective Rh P nanowires (d-Rh P NWs) and perfect Rh P nanocubes (p-Rh P NCs) are then elaborately synthesized to experimentally represent the d-Rh P and p-Rh P catalytic surfaces. As expected, the P-vacancy-enriched d-Rh 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-Rh P NCs and commercial Pt/C, respectively. This work sheds light on breaking the surface atomic monogeneity for the development of efficient heterogeneous catalysts.