Hierarchical sheet-like W-doped NiCo2O4 spinel synthesized by high-valence oxyanion exchange strategy for highly efficient electrocatalytic oxygen evolution reaction.

[Display omitted] • W-NiCo 2 O 4 -2 hierarchical porous sheets facilitate mass transport. • W6+ doping optimizes the adsorption of oxygen intermediates. • The optimized electron structure promotes the formation of MOOH (M = Co, W). • W6+ doping enhances the intrinsic conductivity of NiCo 2 O 4. Limited specific surface area, active site amount, and intrinsic conductivity inhibit spinels' electrocatalytic oxygen evolution reaction (OER) activity. Herein, we proposed a high-valence oxyanion exchange strategy for preparing hierarchical sheet-like W-NiCo 2 O 4 -2 spinel OER electrocatalyst, which exhibits favorable activity (306 mV overpotential@10 mA cm−2) and durability in 1.0 M KOH solution, and shows an application prospect in a home-made anion exchange membrane (AEM) electrolyzer. BET results showed that the hierarchical structure increased specific surface area and corresponding edge active sites amount, accelerated mass transport and charge transfer. XPS, ex-situ Raman spectroscopy, and HRTEM characterizations dispicted that W6+ doping optimizes e g orbital electron filling and promotes M−OOH (M = Co, W) active species generation. DFT calculations reveal that W6+ doping modulates the adsorption of oxygen intermediates, improving the reaction kinetics, and increasing the density of electronic states nearby the Fermi level, thus enhancing conductivity. This work provides a universal pathway for modulating spinel-based OER electrocatalysts. [ABSTRACT FROM AUTHOR]