CeO2-decorated Fe-doped Ni2P nanosheets for efficient electrocatalytic overall water splitting at high current densities

The development of highly efficient bifunctional electrocatalysts with excellent stability at high current densities for overall water splitting is a challenging but urgent goal. Herein, a novel kind of significantly efficient bifunctional electrocatalysts has been elaborately designed through the fabrication of Fe-doped Ni2P nanosheets decorated with CeO2 nanoparticles (Fe-Ni2P/CeO2) grown on Ni foam. It reveals the existence of electron transfer from Ni2+ to Ce4+, resulting in an increase of Ni3+, of which the strong Lewis acidity promotes the adsorption of OH− and thus facilitates the formation and conversion of oxygen-related intermediates during the water splitting process. The resulting catalyst shows outstanding electrocatalytic activities for both oxygen evolution reaction (OER) (η20 = 190 mV, η1000 = 260 mV) and hydrogen evolution reaction (HER) (η20 = 78 mV, η1000 = 292 mV). Moreover, when utilized for overall water splitting, the Fe-Ni2P/CeO2 requires very low voltages of 1.52 V and 2.88 V to achieve current densities of 20 mA cm−2 and 1000 mA cm−2, respectively, outperforming the Pt/C || RuO2 electrolyzer. Importantly, the as-designed electrolyzer exhibits exceptional durability at a high current density of 1000 mA cm−2. This work has demonstrated an effective strategy for designing non-precious metal heterojunctions with abundant electrocatalytic active sites to drive efficient overall water splitting.