Enhanced electrochemical performance in microengineered NiO films by mechanical loading

The sluggish kinetics of the oxygen evolution reaction (OER) remains a critical bottleneck in renewable energy technologies. To tackle this issue, this study investigates the strain–electrochemical coupling behavior of nickel oxide (NiO) films under mechanical loading. A potential–strain coupling coefficient ς = 1.13 V is obtained by density functional theory calculations for the electrochemical capacitive process, and then a finite element analysis is performed to optimize the pore structures in NiO films for the enhancement of local strain due to the stress concentration under mechanical loading. Compared with nonporous NiO film, the electrochemical current density of optimized dual-scale NiO film increases significantly sixfold under a tensile stress of 15 MPa. Experimentally, the dual-scale NiO film achieves an increase of 13.8% in current density at 0.76 V (vs reversible hydrogen electrode) and a reduction of 29 mV in OER overpotential. This work reveals the existence of a mechanically tunable strain–electrochemical coupling mechanism and provides a novel, cost-effective strategy for enhancing the OER performance of transition metal oxides through rational microstructure design.