Alkali metal-mediated interfacial charge redistribution toward near-optimal water oxidation

The optimal oxidation state and electronic structure of active sites in an electrocatalyst are critical factors for maximizing water-oxidation kinetics. To this end, we developed a heterostructured electrocatalyst for oxygen evolution reaction (OER) comprising La0.5Sr0.5CoO3-delta and Li2MoO4 (LSC/LMO) with optimized oxidation states for active metal sites using an alkali metal mediator. The LSC/LMO system exhibited excellent OER performance (overpotential: 1.45 V at 10 mA cm(-2)) and operational durability (chronoamperometric and cyclic voltammetry stabilities of 200 h at 1.52 V and 5000 cycles). The experimental and computational analyses revealed that lithium atoms accumulated at the LSC/LMO interface exhibit a mediating function toward optimizing the oxidation state and electronic structure of OER active metal elements (cobalt and molybdenum), minimizing the free energy barrier of the rate-determining step in OER. This study provides a new insight for boosting sluggish OER kinetics in water oxidation through in situ oxidation state modulation for heterostructured electrocatalysts.

Automated summary

The optimal oxidation state and electronic structure of active sites in an electrocatalyst are critical factors for maximizing water-oxidation kinetics. In this study, a heterostructured electrocatalyst with optimized oxidation states for active metal sites was developed, showing excellent oxygen evolution reaction (OER) performance and operational durability. The accumulation of lithium atoms at the interface played a mediating role in optimizing the oxidation state and electronic structure of OER active metal elements, leading to a lower energy barrier for the rate-determining step in OER.