Solution combusted ultrathin Co3O4/CoO heterophase electrocatalyst for solar‐energy driven bifunctional water electrolysis.

Potential low‐cost solution combustion synthesis of cobalt oxide (SCSCO: Co3O4/CoO) by using sugar as a fuel for H2 and O2 generation. Co3O4/CoO heterophase provided multiple functional sites and abundant interfaces between the components owing to synergistic effect. The sufficient adsorption sites in SCSCO6 favoured the formation of reactive intermediates which leads to extraordinary OER and HER process. The SCSCO6 exhibits η of 271 mV (102 mV dec−1) for OER and 174 mV (73 mV dec−1) for HER to achieve 10 mA cm−2 (without iR correction). TOF of SCSCO6 (OER: 0.0624 s−1/IrO2‐ 0.0185 s−1; HER: 0.0282 s−1/Pt ‐ 0.0843 s−1) was found to be higher than IrO2 and near to Pt, respectively. The SCSCO6 displays durability of 130 h with potential loss of 3.2 % (OER) and 3.0 % (HER). The disordered oxidation states and high surface area of SCSCO6 (BET ‐ 99 m2 g−1: ECSA ‐ 151.27 m2/g) facilitates the bifunctional activity. The fabricated water electrolyzer consist of SCSCO6//SCSCO6 affords 10 mA cm−2 @1.64 V and exhibits high stability (>130 h: 4.1 % potential loss). The solar‐to‐hydrogen electrolyser (SCSCO6//SCSCO6) afforded non‐stop evolution of H2 and O2 @1.63 V which can be recommended for low‐cost, large‐scale hydrogen production. [ABSTRACT FROM AUTHOR]