Facile Synthesis of 3D NiCoP@NiCoPO_<i>x</i> Core–Shell Nanostructures with Boosted Catalytic Activity toward Oxygen Evolution Reaction

Abstract

As a half-reaction, the intrinsically sluggish oxygen evolution reaction (OER) kinetics severely affects the overall water splitting efficiency. Therefore, we synthesized porous three-dimensional core–shell NiCoP@NiCoPOx nanostructures (3D CS-NiCoP@NiCoPOx) at room temperature via a one-step cyanogel reduction strategy, using NaBH4/NaH2PO2 as a mixed reductant. Specifically, the inner NiCoP core acts as the conductive support for the active catalytic NiCoPOx shell, facilitating the charge transport during OER. With the merits of abundant accessible active sites, fast electron transport, and gas diffusion, CS-NiCoP@NiCoPOx exhibited outstanding electrocatalytic activity and stability toward OER in 1 M KOH electrolyte (e.g., the overpotentials are only 313 mV at 10 mA cm–2 and 398 mV at 100 mA cm–2), outperforming a homemade NiCo nanosheet (NiCo-NS) and commercially available RuO2 catalysts. The developed one-step NiCl2/K3Co(CN)6 cyanogel reduction strategy provides some insights into the synthesis of novel earth-abundant and cost-efficient 3D transition-metal-based nanocatalysts for commercial applications in OER.