Strain-Engineered Oxygen-Modified Nickel Telluride/Nickel Oxide Heterostructures for Bifunctional Alkaline Water Electrocatalysis

We present a strain-engineering strategy for oxygen-modified nickel telluride/nickel oxide heterostructures capable of enabling bifunctional alkaline water electrolysis with performance surpassing Pt and IrO_x benchmarks. The heterostructures are synthesized via electrochemical Te dissolution and mild oxidation of mechanically exfoliated NiTe₂, followed by controlled strain induction through substrate buckling. Atomic-scale simulations and spectroscopic analyses indicate that Te-vacancy/O-substituted NiTe₂ domains promote oxygen-intermediate spillover between adjacent active sites, reducing OER overpotentials. In parallel, strained NiTe₂ domains facilitate hydrogen-intermediate transfer to NiO containing Ni vacancies, leading to accelerated HER kinetics and near-thermoneutral hydrogen adsorption. Strain modulation adjusts the electronic structure and increases active-site density, enabling stable operation at industrial-level current densities (>1 A cm^-2). These findings illustrate how defect chemistry coupled with strain engineering can be utilized to develop high-performance, earth-abundant bifunctional electrocatalysts.