Hierarchical Ni/Ni(OH)2-NiCo2O4 Supported on Ni Foam as Efficient Bifunctional Electrocatalysts for Water Splitting

Developing efficient and cost-effective bifunctional catalytic electrodes is of great importance to water splitting. In this study, hybrid Ni/Ni(OH)2-coated NiCo2O4 nanorods were grown on Ni foam (NF) by a facile growth–conversion–epitaxy approach. The epitaxial decoration of Ni/Ni(OH)2 composite could increase the intrinsic activity of NiCo2O4/NF and enhance the charge-transfer rate. This self-standing hierarchical nanohybrid with unique surface chemistry and interface engineering exhibits an excellent electrocatalytic performance. The optimized Ni/Ni(OH)2-NiCo2O4/NF only requires overpotentials of 53 and 235 mV to reach a current density of 10 mA cm–2 for HER and OER, respectively. The electrolyzer achieved 10 mA cm–2 at a low cell voltage of 1.51 V for water splitting. This work offers a new perspective for rationally designing electrocatalytic materials by surface decoration.