Co-Gallate MOF-Derived Transition Metal Oxide/Phosphide Heterostructure for Efficient Overall Water Splitting

The development of highly active, stable, and earth-abundant bifunctional electrocatalysts presents an innovative approach for achieving overall water splitting with lower cell voltages and generating hydrogen technology. In this study, we present a Co₃O₄/P-C@NiFeP heterostructure composite with 3D nanoflower-like morphology derived from metal-organic framework Co-gallate. Notably, benefiting from the unique morphology and synergy with polycrystalline heterostructure engineering, the as-prepared electrocatalyst Co₃O₄/P-C@NiFeP offers good catalytic activity, exhibiting overpotentials of 281 and 180 mV, and smaller Tafel slope values of about 41.7 and 87.0 mV dec^-1 toward the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) at a current density of 10 mA cm^-2 in alkaline solution, respectively. Additionally, the Co₃O₄/P-C@NiFeP bifunctional catalyst serves as both the cathode and anode for water splitting, exhibiting remarkable efficiency with a low voltage of about 1.67 V to attain a current density of 10 mA cm^-2. Therefore, this work sheds light on the design and synthesis of efficient and low-cost bifunctional electrocatalysts for future practical overall water splitting and other energy conversion and storage technologies by controlling the structures of MOF derivatives.