Synergistic tuning of oxygen vacancies and d-band centers of ultrathin cobaltous dihydroxycarbonate nanowires for enhanced electrocatalytic oxygen evolution

Abstract

Simple and controllable synthesis of efficient and robust non-noble metal electrocatalysts towards the oxygen evolution reaction (OER) is highly desired and challenging in the development of sustainable energy conversion technologies. Herein, we report a facile one-step solvothermal synthesis of cobaltous dihydroxycarbonate nanowires (Co-OCH NWs) with a tunable diameter ranging from 8.7 to 16.7 nm, which were able to exhibit an interesting diameter-dependent catalytic activity towards the OER. It should be highlighted that the thinnest nanowires (8.7 nm) demonstrated the best OER catalytic activity among the as-prepared nanowires, showing an overpotential of only 307 mV at 10 mA cm⁻² and a Tafel slope of 75 mV dec⁻¹ in 1.0 M KOH solution. Based on comprehensive analysis, the excellent electrocatalytic activity of Co-OCH NWs was ascribed to the simultaneous achievement of an enlarged specific surface area, increased oxygen vacancy concentration and favorable position of the 3d-band center for the Co-OCH NWs with the continuous decrease of their diameters. More importantly, this work has emphasized that synergistic tuning of the oxygen vacancy concentration and d-band center position of nanomaterials via facile size control enables boosting their electrocatalytic performance substantially, thereby opening a simple route to design and prepare Earth-abundant electrocatalysts with higher efficiency and lower cost.