Synergizing aliovalent doping and interface in heterostructured NiV nitride@oxyhydroxide core-shell nanosheet arrays enables efficient oxygen evolution

Highlights: • NiV nitride@oxyhydroxide heterostructured nanosheet arrays was proposed. • An in-situ electrochemical surface reconfiguration (ESR) on Ni₃N@Ni₃VN takes place. • Aliovalent V-doping and abundant core-shell interfaces lead to a high OER activity. • NiVN@OOH delivers an ultralow overpotential of 233 mV at 50 mA cm^–2. • DFT calculations were performed to identify the synergistic effect in multiscale structure. An earth-abundant and highly efficient oxygen evolution reaction (OER) electrocatalyst has long been the holy grail in the entire energy conversion chain. Despite the considerable efforts in advancing non-precious-metal candidates by multiscale structural engineering, an adequate structural integration remains a significant challenge in achieving an efficient OER, largely bottlenecked by a low population of active sites and limited synergistic effect. Herein, we propose a synergistic strategy of effectively combining aliovalent doping and interface in the NiV nitride@oxyhydroxide (NiVN@OOH) heterostructured nanosheet arrays, successfully developed by in-situ electrochemical surface reconfiguration (ESR) from the core-shell nanostructured Ni₃N@Ni₃VN aiming for enabling OER kinetics. The thus-optimized NiVN@OOH with abundant core-shell interfaces, vertically aligned nanosheet arrays and purposely-chosen V-doping, demonstrates superior OER activity with an ultralow overpotential of 233 mV at the current density of 50 mA cm_geo⁻², 64-fold rise in catalytic current density at 1.47 V vs. reversible hydrogen electrode (RHE) and 37-fold increase in turn-over frequency at an overpotential of 240 mV, over those of Ni₃N@OOH, together with a robust long-term stability in 1 M KOH. Our DFT calculations further reveal that the synergistic effects of the aliovalent V-doping and interface engineering have boosted the intrinsic OER activity on adjacent oxygen active sites. The discovery in the present work provides a new paradigm of multiscale-controlled synergy for much enhanced electrocatalysis.