Controlling atomic phosphorous-mounting surfaces of ultrafine W2C nanoislands monodispersed on the carbon frameworks for enhanced hydrogen evolution

Abstract

Controllably mounting foreign atoms on the surfaces of earth-abundant electrocatalysts strongly improve their surface electronic properties for optimizing the catalytic performance of surficial sites to an unusual level, and provides a good platform to gain deep insights into catalytic reactions. The present work describes, employing ultrafine W2C nanoislands (average size: 2.3 nm) monodispersed on the N, P dual-doped carbon frameworks as a model system, how to regulate the atomic phosphorous-mounting effect on the surfaces of W2C to derive an active and stable P-mounting W2C (WCP) catalyst for both acidic and alkaline hydrogen evolution reaction (HER). Since in situ phosphorus substitution into carbon sites of preformed W2C nanoislands gradually proceeds from surfaces to solids, so that using a proper amount of phosphorus sources can readily control the surface mounting level to avoid the mass P-doping into the bulk. By this way, the activity per active site of WCP catalyst with robust stability can be optimized to 0.07 and 0.56 H2 s−1 at –200 mV overpotential in acid and base, respectively, which reach up to the several-fold of pure-phase W2C (0.01 and 0.05 H2 s−1). Theoretical investigations suggest that compared with solid P doping, the P mounting on W2C surface can more remarkably enhance its metallicity and decrease the hydrogen release barrier. This finding disclosed a key correlation between surface foreign atom-mounting and catalytic activity, and suggested a logical extension to other earth-abundant catalysts for various catalytic reactions.