Adjusting the valence band center of Co-Ni-bimetallic sulfides through lattice expansion and stacking faults triggered by strain engineering to boost oxygen evolution reaction

Stress engineering can improve catalytic performance by straining the catalyst lattice. An electrocatalyst, Co3S4/Ni3S2-10%Mo@NC, was prepared with abundant lattice distortion to boost oxygen evolution reaction (OER). With the assistance of the intramolecular steric hindrance effect of metal–organic frameworks, slow dissolution by MoO42- of the Ni substrate and recrystallization of Ni2+ was observed in the process of Co(OH)F crystal growth with mild temperature and short time reaction. The lattice expansion and stacking faults created defects inside the Co3S4 crystal, improved the material conductivity, optimized the valence band electron distribution of the material, and promoted the rapid conversion of the reaction intermediates. The presence of reactive intermediates of the OER under catalytic conditions was investigated using operando Raman spectroscopy. The electrocatalysts exhibited super high performance, a current density of 10 mA cm−2 at an overpotential of 164 mV and 100 mA cm−2 at 223 mV, which were comparable to those of integrated RuO2. Our work for the first time demonstrates that the dissolution–recrystallization triggered by strain engineering is a good modulation approach to adjust the structure and surface activity of catalyst, suggesting promising industrial application.