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

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.