Deciphering the In Situ Reconstruction of Metal Phosphide/Nitride Dual Heterostructures for Robust Alkaline Hydrogen Evolution Above 3Acm-2.

Abstract

Hydrogen evolution reaction (HER) in neutral or alkaline electrolytes is appealing for sustainable hydrogen production driven by water splitting, but generally suffers from unsatisfied catalytic activities at high current densities owing to extra kinetic energy barriers required to generate protons through water dissociation. In response, here, a competitive Ni3N/Co3N/CoP electrocatalyst with multifunctional interfacial sites and multilevel interfaces, in which Ni3N/CoP performs as active sites to boost initial water dissociation and Co3N/CoP accelerates subsequent hydrogen adsorption process as confirmed by density functional theory calculations and in situ X-ray photoelectron spectroscopy analysis, is reported. This hybrid catalyst possesses extraordinary HER activity in base, featured by extremely low overpotentials of 115 and 142mV to afford 500 and 1000mAcm-2, respectively, outperforming most ever-reported metal phosphides-based catalysts. This catalyst presents an ultrahigh current density of 3545mAcm-2 by a factor of 4.96 relative to noble Pt/C catalysts (715mAcm-2) at 0.2V. Assembled with Fe(PO3)2/Ni2P anode, industrial-level current densities of 500/1000mAcm-2 at ultralow cell voltages of 1.62/1.66V for overall water electrolysis with outstanding long-term stability are actualized. More interestingly, this hybrid catalyst also performs well in acidic, neutral freshwater, and seawater requiring relatively low overpotentials of 140, 290, and 331mV to reach 500mAcm-2. Particularly, this catalyst can withstand electrochemical corrosion without obvious activity decay at the industrial-level current densities for over 100h in base. This work provides a cornerstone for the construction of advanced catalysts operated in different pH environments.