Co₃O₄/WO₃/C Nanorods with Porous Structures as High-Performance Electrocatalysts for Water Splitting

The recent promise of the hybridization of mesoporous carbon with transition metal oxides as a desirable catalyst for the oxygen evolution reaction (OER), and its extension to the hydrogen evolution reaction (HER) to achieve the goal of overall water splitting applications, remains a major challenge. Here, a unique environmentally benign mesoporous Co 3 O 4 /WO 3 /C bifunctional electrocatalyst is developed from converting cellulose waste, specifically in the form of sugarcane bagasse, by pyrolysis followed by a two-step hydrothermal strategy that can catalyze electrochemically OER and HER activity in an efficient and robust manner. The electrocatalyst delivers low overpotentials of 229/295 mV and a Tafel slope of 63/77 mV/dec –1 for both alkaline and acidic media, respectively, for OER along with the overpotential of 123 mV and a Tafal slope of 36 mV/dec –1 for HER to reach a current density of 10 mA/cm 2 . We hypothesized that an electronic synergistic effect between the transition metals might be responsible for promoting HER and OER activity, which was confirmed by density functional theory studies. This work opens a unique pathway to develop highly efficient, but low cost, electrocatalysts for water splitting applications.