Tailoring Intermediate Adsorption Through d ‐band Mismatch Strategy of Heterojunction to Achieve Industrial Overall Water Splitting

ABSTRACT Adjusting the d ‐band center of catalysts through heterojunction construction represents an effective approach for enhancing the catalytic activity. Nevertheless, the precise modulation pathways of d ‐band centers still require systematic elucidation. In this work, a Ni ₃ Mo/Ni ₃ N junction is constructed to investigate d ‐band engineering, and a d ‐band mismatch mechanism has been proposed for the first time to elucidate the synergistic effect between Ni ₃ Mo and Ni ₃ N for improved HER and OER. Specifically, the dissociation of H ₂ O can be achieved on the Ni ₃ Mo surface while the adjacent Ni ₃ N sites catalyze the subsequent evolution reactions. Remarkably, the Ni ₃ Mo–Ni ₃ N/NF achieves ultra‐low overpotentials of 15 mV (HER) and 155 mV (OER) at 10 mA cm ⁻² , and just 228 mV (HER) and 459 mV (OER) at 1 A cm ⁻² . Most strikingly, the HER performance of Ni ₃ Mo–Ni ₃ N/NF is superior to that of the Pt/C catalyst across all current densities, marking it as a standout among the NiMo‐based catalysts documented so far. Additionally, the Ni ₃ Mo–Ni ₃ N/NF demonstrates outstanding performance in an anion exchange membrane water electrolyzer (AEMWE), delivering the current density of 4 A cm ⁻² at a mere 2.12 V while maintaining stable operation for 1000 h at 1 A cm ⁻² , showing great potential for practical applications.