Sequential reactant water management by complementary multisite catalysts for surpassing platinum hydrogen evolution activity

Alkaline hydrogen evolution reaction (HER) offers a near-zero-emission approach to advance hydrogen energy. However, the activity limited by the multiple reaction steps involving H₂O molecules transfer, absorption, and activation still unqualified the thresholds of economic viability. Herein, we proposed a multisite complementary strategy that incorporates hydrophilic Mo and electrophilic V into Ni-based catalysts to divide the distinct steps on atomically dispersive sites and thus realize sequential regulation of the HER process. The Isotopic labeled in situ Raman spectroscopy describes 4-coordinated hydrogen bonded H₂O to be free H₂O passing the inner Helmholtz plane in the vicinity of the catalysts under the action of hydrophilic Mo sites. Furthermore, potential-dependent electrochemical impedance spectroscopy (EIS) reveals that electrophilic V sites with abundant 3d empty orbitals could activate the lone-pair electrons in the free H₂O molecules to produce more protic hydrogen, and dimerize into H₂ at the Ni sites. By the sequential management of reactive H₂O molecules, NiMoV oxides multisite catalysts surpass Pt/C hydrogen evolution activity (49 mV@10 mA∙cm⁻² over 140 h). Profoundly, this study provides a tangible model to deepen the comprehension of the catalyst–electrolyte interface and create efficient catalysts for diverse reactions.