Negatively Charging Nonprecious Metal Phosphides/Selenides via General Polyaniline Coating for Improved Alkaline H-2 Evolution

Nonprecious metal phosphides/selenides have been extensively investigated as competent electrocatalysts for the alkaline hydrogen evolution reaction (HER) toward H-2 production, although high overpotentials are still needed due to the sluggish kinetics of the alkaline HER associated with water dissociation. Herein, we present a universal approach to negatively charge Ni5P4, NiSex , and CoPx , via a one-step aniline electropolymerization coating, for an improved alkaline HER. Physicochemical characterizations and density functional theory (DFT) calculations reveal that the surface-coated polyaniline (PANi) renders underlying active species negatively charged due to strong electronic coupling, which leads to accelerated water dissociation via attractive interaction between electron-deficient hydrogen atoms and the repulsive interaction between electron-rich hydroxyl group. Accordingly, the resulting Ni5P4@PANi for instance exhibits exceptional alkaline HER performance with a significant 680 mA cm(-2) at an overpotential of 300 mV, outperforming those of the Ni5P4 counterpart (155 mA cm(-2)) and Pt/C (430 mA cm(-2)) under the same conditions.

Automated summary

The researchers develop a universal approach to negatively charge nonprecious metal phosphides/selenides through one-step aniline electropolymerization coating, which greatly improves the alkaline HER. Physicochemical characterizations and DFT calculations show that the surface-coated polyaniline (PANi) renders the active species negatively charged, resulting in accelerated water dissociation. The resulting Ni5P4@PANi exhibits exceptional alkaline HER performance with a significant 680 mA cm(-2) at a 300 mV overpotential.