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 (Ni₂P@CeO₂) hybrid nanoarray on nickel foam was designed via selective-phosphorization of nickel hydroxide@cerium oxide (Ni(OH)₂@CeO₂). Benefiting from CeO₂ as the “electron pump,” it leads to electron transfer from Ni₂P to the CeO₂ 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 CeO₂ 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 Ni₂P side through the spillover process. Contributing to the synergistic effect of double-active sites, the Ni₂P@CeO₂/NF electrode exhibits brilliant catalytic performance for HER with 62 mV to attain 10 mA/cm² and exceptional durability over 100 h in alkaline solution at ~ 100 mA/cm². Meanwhile, attributing to the similar interface electron redistribution effect, the precursor Ni(OH)₂@CeO₂/NF likewise displays excellent oxygen evolution reaction (OER) electrocatalytic performance, which only requires 229 mV to arrive at 10 mA/cm², even better than benchmark ruthenium dioxide (RuO₂). Hence, the assembled Ni(OH)₂@CeO₂/NF||Ni₂P@CeO₂/NF system only needs 1.53 V to achieve 10 mA/cm² 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 CeO₂ ensures that interface-engineered Ni₂P@CeO₂ hybrid nanoarrays prepared via selective-phosphorization treatment present superior HER catalytic performance