Heterogeneous interface engineering for boosting electron transfer induced by MOF-derived Yolk-shell trimetallic phosphide nanospindles for robust water oxidation electrocatalysis

The heterogeneous interface engineering of nanocatalysts has been proved as an efficient strategy to promote the oxygen evolution reaction (OER) catalytic performance. Different from the conventional hollow structures, the yolk-shell construction could defend the distortion and dissolution during OER for stability improvement. However, it is still a great challenging to simultaneously construct heterogeneous interface and yolk-shell structure based on electrocatalysts with well-tuned composition and structure. Herein, we developed a facile synthetic method to prepare the yolk-shell trimetallic phosphide catalysts by starting with MIL-88A nanospindles templates. Benefitting from heterogeneous interface with fast electron transfer, yolk-shell architecture with rich channels for mass transportation, and active metal doping with electron structure modulation, the obtained CoNiFeP yolk-shell nanospindles (YSNSs) catalysts displayed superior OER catalytic properties with the overpotential of only 261 mV to deliver a current density of 10 mA cm−2 in alkaline media. Furthermore, the yolk-shell architecture endowed CoNiFeP with remarkable OER stability for 60 h. By coupling CoNiFeP with Pt/C electrodes to drive overall water splitting, an ultralow cell voltage of 1.56 V is required. The experimental and mechanistic studies indicated the optimized binding energy of *OOHad and *OHad intermediates by constructing robust phosphide interface.