Construction of interface-engineered coral-like nickel phosphide@cerium oxide hybrid nanoarrays to boost electrocatalytic hydrogen evolution performance in alkaline water/seawater electrolytes

Fabricating a functional heterogeneous interface to enhance catalytic performance is quite significant for developing high-efficiency electrocatalysts. Herein, a coral-like nickel phosphide@cerium oxide (Ni 2 P@CeO 2 ) hybrid nanoarray on nickel foam was designed via selective-phosphorization of nickel hydroxide@cerium oxide (Ni(OH) 2 @CeO 2 ). Benefiting from CeO 2 as the “electron pump,” it leads to electron transfer from Ni 2 P to the CeO 2 side, and induces electron redistribution in the interface boundary, thereby optimizing the H* adsorption free energy in the hydrogen evolution reaction (HER) process. As hypothesized, the water molecules will preferentially adsorb on the CeO 2 side due to its better affinity for oxygen-containing species, and will readily break down into OH* and H* at a lower energy barrier. Subsequently, benefiting from the lower H* adsorption free energy of P sites, the generated H* will migrate to the Ni 2 P side through the spillover process. Contributing to the synergistic effect of double-active sites, the Ni 2 P@CeO 2 /NF electrode exhibits brilliant catalytic performance for HER with 62 mV to attain 10 mA/cm 2 and exceptional durability over 100 h in alkaline solution at ~ 100 mA/cm 2 . Meanwhile, attributing to the similar interface electron redistribution effect, the precursor Ni(OH) 2 @CeO 2 /NF likewise displays excellent oxygen evolution reaction (OER) electrocatalytic performance, which only requires 229 mV to arrive at 10 mA/cm 2 , even better than benchmark ruthenium dioxide (RuO 2 ). Hence, the assembled Ni(OH) 2 @CeO 2 /NF || Ni 2 P@CeO 2 /NF system only needs 1.53 V to achieve 10 mA/cm 2 in alkaline solution. Moreover, the electrolyzer also presents brilliant electrocatalytic activity and stability in alkaline natural seawater electrolyte with higher reserves on earth. Graphical Abstract “Electrons pump” effect of CeO 2 ensures that interface-engineered Ni 2 P@CeO 2 hybrid nanoarrays prepared via selective-phosphorization treatment present superior HER catalytic performance