Defect and Interface Engineering of Three-Dimensional Open Nanonetcage Electrocatalysts for Advanced Electrocatalytic Oxygen Evolution Reaction

Defect engineering and interface engineering are two efficient approaches to promote the electrocatalytic performance of transition metal oxides (TMOs) by modulating the local electronic structure and inducing a synergistic effect but usually require costly and complicated processes. Herein, a facile electrochemical etching method is proposed for the controllable tailoring of the defects in a three-dimensional (3D) open nanonetcage CoZnRuO_x heterostructure via the in situ electrochemical etching to remove partial ZnO. The highly open 3D nanostructures, numerous defects, and multicomponent heterointerfaces endow the CoZnRuO_x nanonetcages with more accessible active sites, moderated local electronic structure, and strong synergistic effect, thereby enabling them to not only deliver an ultralow overpotential (244 mV @ 10 mA cm^-2) for oxygen evolution reaction (OER) but also high-performance overall water electrolysis by coupling with commercial Pt/C, with a potential of 1.52 V at 10 mA cm^-2. Moreover, experiments and characterizations also reveal that the remaining Zn²⁺ can facilitate OH^- adsorption and charge transfer, which also further improves the electrocatalytic OER performance. This work proposes a promising strategy for creating surface defects in heterostructured TMOs and provides insights to understand the defect- and interface-induced enhancement of OER electrocatalysis.