Converting CoMoO₄ into CoO/MoO_<i>x</i> for Overall Water Splitting by Hydrogenation

Abstract

Special structures of materials often bring in unprecedented catalytic activities, which are critical in realizing large-scale hydrogen production by electrochemical water splitting. Herein, we report a CoO/MoO_<i>x</i> crystalline/amorphous structure as an effective bifunctional electrocatalyst for water splitting. Converted from CoMoO₄ by hydrogenation, the CoO/MoO_<i>x</i>, featured with crystalline CoO in amorphous MoO_<i>x</i> matrix, displays superior catalytic activities toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). It shows small onset overpotentials of 40 and 230 mV for the HER and OER in 1.0 M KOH, respectively, and overall water splitting starting at 1.53 V with a robust stability. The high catalytic activity of the CoO/MoO_<i>x</i> is benefited from the large defect-rich interface between CoO and MoO_<i>x</i>, along with the amorphous nature of MoO_<i>x</i>. Thus, this study demonstrates the effectiveness of structural manipulation in developing highly active electrocatalysts for overall electrochemical water splitting