NiSe synergistically enhancing FeNi bimetallic site catalysts for efficient bifunctional water electrolysis catalysts and mechanistic insights

The development of efficient non-precious metal catalysts is crucial for the large-scale application of hydrogen production via water electrolysis. Coupling FeNi catalysts with transition metal chalcogenides has proven to be an effective strategy for enhancing catalytic performance. However, limited attention has been given to simultaneously regulating electronic structure and local environmental factors. In this work, we synthesised Fe-Ni-C and NiSe heterostructures, that leverage enhanced water adsorption and rapid electron transfer at their surfaces. Among them, NS/2Fe-Ni-C@600 exhibits excellent catalytic performance, requiring low overpotentials of only 276 mV for oxygen evolution reaction (OER) and 292 mV for hydrogen evolution reaction (HER) reaching to 10 mA·cm −2 in 1 M KOH. Moreover, it exhibited remarkable stability, with no significant degradation observed during 12 h of constant potential stability testing. Simulation calculations show that NiSe increases the water adsorption capacity at the Fe-Ni-C interface on the OER reaction process on the metal catalyst surface at the microscopic level. It regulates the orbital overlap between Fe and Ni above the Fermi energy level, and effectively reduces the adsorption energy of electrolytic water reaction intermediates of Fe-Ni-C. This strategy of constructing heterojunctions between bimetallic catalysts and transition metal sulfides modulates the electronic structure and enhances the surface water distribution, which contributes to improving the reactivity of electrolytic water catalysts. This study further deepens the design and understanding of bimetallic catalysts.