N, S co-doped NiCo2O4@CoMoO4/NF hierarchical heterostructure as an efficient bifunctional electrocatalyst for overall water splitting

Electrocatalytic overall water splitting technology has received considerable attention in recent years. The fabrication of low-cost, earth-rich and potent bifunctional electro-catalysts is vital for hydrogen evolution (HER) and oxygen evolution reactions (OER). Herein, the N and S co-doped NiCo2O4@CoMoO4 heterostructures (N, S-NCO@CMO400) are fabricated by CVD and hydrothermal methods. N and S atoms as auxiliary active centers can increase the activity of Ni, Co and Mo atoms at the same time. Hierarchical hetero-structures generate more interfaces to accelerate mass transfer and enlarge the electro-chemical surface area, which greatly enhances the catalytic activity. The catalyst displays outstanding OER performance. The overpotentials of OER and HER are 165 and 100 mV at a current density of 10 mA cm-2, respectively. More importantly, the N, S-NCO@CMO400- based water splitting cell has a low voltage of 1.46 V at 10 mA cm-2. Furthermore, the N, S-NCO@CMO400 runs for 120 h in stable operation. This work provides new ideas for the design of hierarchical heterostructures with two-element incorporation. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.