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

Abstract

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/VOx catalyst is constructed using vanadium oxide as a sacrificial template combined with a nitrogen doping strategy. During the OER process, VOx 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/VOx 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.