Spin-selective charge transfer at oxygen-deficient NiMoO4/Co3O4/NF interfaces enables high-performance alkaline water splitting

A novel NiMoO 4 /Co 3 O 4 /NF was synthesized via two-step hydrothermal and calcination methods. • The interfaces in Co 3 O 4 /NiMoO 4 core@shell heterostructure facilitates charge transfer and exposes substantial active sites for HER/OER. • The catalyst achieves impressive HER ( η 10  = 121 mV), OER ( η 100  = 202 mV) performance, couple with prolong stability (>120 h) in overall water splitting. • DFT calculations illustrate oxygen vacancies and interfaces activate spin-selective charge transfer, downshift d-band center and optimize adsorption ability of critical intermediates in OER. The synthesis of highly actively bifunctional electrocatalysts with robust durability for hydrogen production by overall water splitting remains constrained by sluggish oxygen evolution reaction/hydrogen evolution reaction (OER/HER) intrinsic kinetics and incompatible reaction environments. Herein, an oxygen vacancy-enriched NiMoO 4 /Co 3 O 4 /NF heterostructure catalyst with abundant tailored interfaces was fabricated via a two-step hydrothermal-calcination strategy through in situ growing NiMoO 4 nanosheets on Co 3 O 4 nanowires-coated nickel foam. The as-prepared catalyst delivers exceptional bifunctional activities in alkaline media (OER: η 100  = 202 mV, HER: η 10  = 121 mV). In the overall water-splitting system, it requires applied voltages of 1.51 V (@ 10 mA cm⁻ 2 ) and 1.73 V (@ 100 mA cm⁻ 2 ), and exhibits prolonged stability (120 h) by addressing Mo leaching. DFT calculations reveal a spin-selective charge transfer driven by the spin-state mismatch between low-spin Co 3+ and high-spin Ni 2+ at the interface. This mismatch along with oxygen defect promotes electron transfer from Co to Ni, filling the antibonding e g orbitals of Ni sites to reduce Ni coordination, downshifting the d -band center and optimizing the intermediates adsorption ability in OER. This study furnishes advanced perspectives on interfacial synergistic effects and oxygen vacancies in catalytic reactions, thus establishing a significant foundation in renewable energy conversion. A novel oxygen vacancy-rich NiMoO 4 /Co 3 O 4 /NF heterostructure with tailored interfacial architecture was fabricated via a two-step hydrothermal-calcination approach. The catalyst exhibits impressive OER ( η 100 = 202 mV) and HER ( η 10 = 121 mV) performance with prolonged stability (>120 h) in overall water splitting. DFT calculations reveal that oxygen vacancy-assisted interfacial spin configuration collaboratively regulates electron redistribution and d -band center, thus reducing kinetic barriers for OER. Download: Download high-res image (157KB) Download: Download full-size image