Multiphase nanosheet-nanowire cerium oxide and nickel-cobalt phosphide for highly-efficient electrocatalytic overall water splitting

Herein, a hybrid nanowire-nanosheet structure made of the cerium oxide and nickel-cobalt phosphide (CeO2-NiCoPx) compound is in situ engineered on the Ni-Co foam (CeO2-NiCoPx/NCF) for the robust water splitting (HER and OER), and the overpotentials of synthesized CeO2-NiCoPx/NCF are about 39 mV for HER and 260 mV for OER at a current density of 10 mA cm−2 (j10). Meanwhile, the nanostructure of CeO2-NiCoPx is well preserved after a long-term electrocatalytic process (100 h) at a large current density of 100 mA cm−2 (j100). When the CeO2-NiCoPx/NCF simultaneously acts as the HER and OER electrodes, the potential of 1.49 V is obtained for transferring j10 with an excellent durability. Theoretical simulations and in operando Raman spectroscopy reveal that the Co and Ni atoms for CeO2-NiCoPx/NCF catalyst are likely to act as the pivotal reaction centers for HER and OER processes, respectively.