Engineering anion-induced electric field in selenide heterojunctions for enhanced alkaline HER

The pursuit of sustainable hydrogen production via water electrolysis urgently demands electrocatalysts reconciling industrial-grade activity, durability, and cost-effectiveness for the hydrogen evolution reaction. While transition metal selenides (TMSs) offer noble-metal alternatives with tunable electronic structures, monophasic variants suffer from compromised charge transfer kinetics, limited active site exposure, and cathodic degradation. Herein, we propose selenium anion electric field engineering via molybdenum ions regulated heterointerface construction in Ni 3 Se 4 /MoSe 2 heterojunctions anchored on nickel foam (denoted as Ni 3 Se 4 /MoSe 2 @NF). Multiscale mechanistic studies reveal that the reconstructed built-in electric field around the selenium anions in MoSe 2 demonstrates a lower hydrogen adsorption free energy (ΔG H*  = 0.166 eV) via d-band center, with accelerating interfacial charge transfer. The resultant catalyst achieves an ultralow overpotential of 60 mV at 10 mA cm −2 (η 10 ) with a Tafel slope of 65.17 mV dec −1 . Particularly noteworthy is its industrial-grade stability, which exhibits only a 20 mV (η 100 ) increase after 200 h of continuous operation in 1 M KOH, coupled with near-unity Faradaic efficiency (over 98 %). This work establishes a heterointerface microenvironment regulation paradigm to break the activity-stability trade-off, providing a universal design principle for durable, high-flux water electrolysis.