Deciphering d–sp Orbital Interaction in MnSe₂–CoSe₂ with a Built-in Electric Field toward Enhanced Water and Seawater Oxidation Electrocatalysis

Constructing efficient hybridized catalysts for water and seawater electrolysis, along with an understanding of their function mechanisms, is essential for advancing green hydrogen production. Herein, a uniform MnSe₂-CoSe₂ coating is constructed on graphite felt (GF) through a straightforward electrodeposition-selenization approach. The in situ cocrystallization process generates numerous heterointerfaces, which enhance catalytic activity and stability through the establishment of an internal electric field and the modulation of d-sp orbital interactions. Specifically, antibonding regulation facilitates the adsorption and desorption of oxygen-related species, enabling MnSe₂-CoSe₂/GF to require low overpotentials of 363 and 394 mV to achieve 500 mA cm^-2 oxygen evolution in alkaline water and seawater, respectively. Meanwhile, bonding enhancement contributes to improved chemical stability and corrosion resistance, allowing the catalyst to remain stable for more than 200 h with a minimal 9.8% current decay during seawater oxidation. This study provides an innovative method for constructing interface-wealthy heterogeneous structures and reveals the mechanisms behind high-performance seawater electrocatalysis, which is highly valuable for green hydrogen production.