Excess Activity Tuned by Distorted Tetrahedron in CoMoO4 for Oxygen Evolution

Oxygen vacancies enable modulating surface reconstruction of transition metal oxides containing metal-oxygen polyhedrons into metallic oxyhydroxide for oxygen evolution reaction (OER), while revealing reconstructing mechanism is stuck by the requirement to precisely control exact sites of these vacancies. Herein, oxygen vacancies are localized only within MoO4 tetrahedrons rather than CoO6 octahedrons in CoMoO4 catalyst, guaranteeing coherent reconstruction of CoO6 octahedrons into pure CoOOH with tunable activities for OER. Meanwhile, distorted tetrahedron accelerates the dissolution of Mo atoms into alkaline electrolyte, triggering spontaneous transition of partial CoMoO4 into Co(OH)(2). CoO6 octahedrons in both CoMoO4 and Co(OH)(2) can transform pure CoOOH completely at lower potential, resulting in excess intrinsic activity whose summit is identified by overpotential at 10 mA cm(-2) with 22.9% reduction and Tafel slope with 65.3% reduction. Well-defined manipulation over the distorted polyhedrons offers one versatile knob to precisely modulate electronic structure of oxide catalysts with outstanding OER performance.

Automated summary

Oxygen vacancies in transition metal oxides can be used to modulate surface reconstruction for enhancing the oxygen evolution reaction (OER). In this study, oxygen vacancies were specifically localized within MoO4 tetrahedrons rather than CoO6 octahedrons in the CoMoO4 catalyst, resulting in the coherent reconstruction of CoO6 octahedrons into pure CoOOH with tunable OER activities. The manipulated distorted polyhedrons facilitated the complete transformation of CoO6 octahedrons into pure CoOOH at lower potentials, leading to a significantly improved intrinsic activity for OER.