Lattice-strain engineering of CoOOH induced by NiMn-MOF for high-efficiency supercapacitor and water oxidation electrocatalysis

Lattice strain engineering is desirable to accelerate the electrochemical reaction kinetics but still lacks exploration. Here, we have endowed NiMn-MOF@CoOOH with multiple strains, which were introduced by NiMn-MOF. In such hybrid material, the NiMn-MOF not only stabilizes the structure to prevent the material from breaking during the electro-oxidation phase change process but also serves as an anchor point to tightly connect Co ions. The surface of CoOOH undergoes lattice stretching and compression and builds abundant vacancies and dislocations. The multiple lattice strains enable accelerated ion conduction through tensile/compressive strain and introduce additional electrochemically active sites. Regional vacancies and dislocation can change the stoichiometric ratio of some regions, leading to local electric field distortion and electron density redistribution. Moreover, the stacked network structure of the double-layer sheet provides more electrochemical active interfaces for electrochemical reactions, which greatly reduces the ion transport distance and promotes the rapid diffusion of electrolyte ions. The as-obtained NiMn-MOF@CoOOH demonstrates a superb capacity of 1771.4 at 1 A g⁻¹ in supercapacitors. Meanwhile, when facing the water oxidation electrocatalysis reaction, it delivers low overpotentials of 221 mV at 10 mA cm⁻² in an alkaline electrolyte. This report provides a novel strategy for lattice strain engineering on advanced materials for sustainable applications.