Metastabilizing the Ruthenium Clusters by Interfacial Oxygen Vacancies for Boosted Water Splitting Electrocatalysis

Abstract

Metal-support interaction (MSI) is witnessed as an essential manner to stabilize active metals and tune catalytic activity for heterogonous water splitting. Kinetically driving the water electrolysis (WE) appeals for a rational MSI system with the coupled electron-donating/accepting (e-D/A) characters for hydrogen/oxygen evolution reactions (HER/OER). However, the metal stabilization effect by MSI will in turn restrict the deblocking of e-D/A properties and challenge the full electrocatalytic optimization. This study profiles a heterostructure featuring metastable Ru clusters on defective NiFe hydroxide (Ru/d-NiFe LDH) support as a low-precious (approximate to 2 wt%) catalytic platform for efficient WE. It is indicated that the interfacial oxygen vacancies can deviate the stable Ru 4d5 orbit to a metastable Ru2+delta state, and regulate the metal d-band center levels toward the facilitated HER/OER processes. Resultantly, the Ru/d-NiFe LDH heterostructure attains the ultralow overpotentials at 10 mA cm-2 for Pt-beyond alkaline HER (18 mV) and OER (220 mV) with fast kinetics and durability. The symmetrical water electrolyzer delivers a promising voltage of 1.49 V at 10 mA cm-2 in 1 m KOH and efficient seawater splitting performance. This work carries interesting opportunities in rationalizing sophisticated metal-support electrocatalysts through metal-site metastabilization engineering. A heterostructure featuring metastable Ru clusters on defective NiFe hydroxide (Ru/d-NiFe LDH) support is profiled as a low-precious (approximate to 2 wt%) catalytic platform for efficient Pt/RuO2-beyond water electrolysis. The oxygen vacancies on the NiFe-LDH support are revealed to enhance the interfacial charge transfer at the RuONi bridge, giving rise to metastable Ru2+delta sites deviated from the half-filled 4d5 orbital stable state. image