Carbonate-Hydroxide Induced Metal-Organic Framework Transformation Strategy for Honeycomb-Like NiCoP Nanoplates to Drive Enhanced pH-Universal Hydrogen Evolution.

ABSTRACT

Developing a low-cost, pH-universal electrocatalyst is desirable for electrochemical water splitting but remains a challenge. NiCoP is a promising non-noble hydrogen-evolving electrocatalyst due to its high intrinsic electrical conductivity, fast mass transfer effects, and tunable electronic structure. Nevertheless, its hydrogen evolution reaction (HER) activity in full pH-range has been rarely developed. Herein, a Ni-Co carbonate-hydroxide induced metal-organic framework transformation strategy is proposed to in situ grow porous, honeycomb-like NiCoP nanoplates on Ni foam for high-performance, pH-universal hydrogen evolution reaction. The resultant NiCoP catalyst exhibits a highly 2D nanoporous network in which 20-50 nm, well-crystalline nanoparticles are interconnected with each other closely, and delivers versatile HER electroactivity with η10 of 98, 105, and 97 mV in 1 m KOH, 0.5 m H2 SO4 , and 1 m phosphate buffer solution electrolytes, respectively. This overpotential remarkably surpasses the one of commercial Pt/Cs in both neutral and alkaline media at a large current density (>100 mA cm-2 ). The corresponding full water-splitting electrolyzer constructed from the 2D porous NiCoP cathode requires only a cell voltage of 1.43 V at 10 mA cm-2 , superior to most recently reported electrocatalysts. This work may open up a new avenue on the rational design of nonprecious, pH-universal electrocatalyst.