Pre-intercalation of phosphate into Ni(OH)2/NiOOH for efficient and stable electrocatalytic oxygen evolution reaction.

[Display omitted] • A volume OER (VOER) strategy for layered hydroxides was presented. • Phosphate-intercalated Ni(OH) 2 /NiOOH loaded on Ni foam was prepared as a VOER catalyst. • The catalyst displays better OER activity than benchmark RuO 2 and most Ni-based catalysts. • The long-term stability is over 1000 h, much better than other Ni-based OER catalysts. • The role of phosphate intercalation on VOER has been revealed. Layered Ni(OH) 2 /NiOOH hydroxides are effective oxygen evolution reaction (OER) electrocatalysts, but their activities are still inferior to those of benchmark RuO 2 and IrO 2. Notably, the long-term stability becomes a significant challenge. Herein, we present a novel volume OER (VOER) strategy to solve the problems via pre-intercalation of phosphate. Phosphate-intercalated Ni-Ni(OH) 2 /NiOOH electrode was prepared by a two-step electrochemical method. The obtained porous electrode exhibits outstanding OER performance in the alkaline phosphate electrolyte with the overpotentials of 129 and 243 mV at 10 and 100 mA cm−2, respectively, and stability for 1000 h. The exceptional performance is mainly ascribed to effective VOER and elimination of the interlayer-produced protons, because the phosphate-intercalation enhances the interlayer water content, interlayer spacing and proton transport ability, endows the interlayers with proton buffering capacity, and alters the chemical environment of the interlayer Ni-O. The finding provides a strategy to develop highly efficient and stable OER materials and reaction systems for layered transition metal hydroxides. [ABSTRACT FROM AUTHOR]