Synergistic sacrificial templating and electronic modulation enabled surface reconstruction of NiFe₂O₄ for efficient...

Developing stable and efficient non-precious metal oxygen evolution reaction (OER) electrocatalysts remains a key challenge for practical water electrolysis applications. Herein, a hierarchical nanostructured N-NiFe₂O₄/VO_x catalyst is constructed using vanadium oxide as a sacrificial template combined with a nitrogen doping strategy. During the OER process, VO_x gradually dissolves as a sacrificial phase, maintaining overall structural stability, suppressing the aggregation of NiFe₂O₄ and exposing more active sites. Nitrogen doping optimizes the electronic structure, enhancing charge transfer efficiency and reaction kinetics. This synergistic effect promotes rapid surface reconstruction of the NiFe₂O₄ spinel, generating a catalytically active MOOH (M = Ni, Fe) phase, and thus significantly improves the OER performance. The N-NiFe₂O₄/VO_x catalyst requires an overpotential of only 300 mV to achieve a current density of 500 mA cm^-2 in 1 M KOH, and it can operate stably for 260 h. Furthermore, under fluctuating current and simulated operating conditions (6 M KOH, 80 °C), it still exhibits satisfactory activity and durability. This work offers insights into the rational design of high performance OER electrodes.