Oxygen vacancy-enriched SnO2/NiO n–p heterointerfaces for high-efficiency oxygen evolution reaction catalysis

Abstract

The quest for efficient “green” hydrogen generation through renewable electricity-powered water splitting confronts profound challenges, most notably the progressive deterioration of catalytic performance and significant constraints imposed by mass transport inefficiencies under industrially pertinent high-current conditions. To overcome these formidable challenges, we have engineered a structurally refined, oxygen-vacancy-enriched SnO₂/NiO n–p hollow nanotube-structured heterostructure (denoted as SnO₂/NiO HNTs) via a facile electrospinning and post-calcination-mediated interfacial design. Rooted in a hollow nanofiber structure, this innovative interface facilitates the formation of a catalytically potent architecture, bestowing dual functional merits: (1) an electronically tailored oxygen-enriched surface that precisely tunes the adsorption energetics of oxygen intermediates and (2) a meticulously engineered three-dimensional (3D) porous framework composed of one-dimensional (1D) nanofibers, which promotes swift bubble release and efficient electrolyte penetration. This harmonious architectural synergy enables the SnO₂/NiO HNT electrode to attain a remarkably low oxygen evolution reaction (OER) overpotential of 200 mV at a current density of 10 mA cm⁻², while sustaining robust operational stability for over 90 hours. In situ Raman spectroscopic analysis reveals that the strategic construction of the n–p heterojunction not only dramatically facilitates the surface reconstruction of NiO to yield authentic NiOOH active species, but also substantially lowers the formation energy barrier for oxygen-containing intermediates during the OER, thereby markedly enhancing the overall catalytic efficiency of the reaction. The demonstrated interface engineering strategy with an n–p heterojunction provides a generalized design paradigm for overcoming mass transport limitations in high-rate gas evolution electrocatalysis.