Nanoporous Nonprecious High-Entropy Alloys as Multisite Electrocatalysts for Ampere-Level Current-Density Hydrogen Evolution

Abstract

Developing robust nonprecious metal-based electrocatalysts toward hydrogen evolution reaction is crucial for large-scale hydrogen production via electrochemical water splitting. Herein, surface high-entropy NiFeCoCuTi alloy on column-nanostructured nanoporous Ni skeleton is reported as multisite electrocatalyst for highly efficient hydrogen evolution in nonacidic environments by making use of surface heterogeneous atoms with distinct hydrogen and hydroxyl adsorption behaviors to accelerate water dissociation and mediate adsorption of hydrogen intermediates for combination into molecules. Associated with the column-nanostructured nanoporous Ni skeleton that facilitates electron transfer/mass transportation and enables highly accessible and abundant electroactive sites, self-supported monolithic nanoporous high-entropy NiFeCoCuTi alloy electrode exhibits superior nonacidic hydrogen evolution reaction (HER) electrocatalysis, with low onset overpotentials and Tafel slopes. It only takes overpotential of as low as ≈209 mV to deliver ultrahigh current density of 2 A cm−2, along with exceptional stability for more than 240 h, in 1 m KOH electrolyte. These outstanding properties make nanoporous NiFeCoCuTi high-entropy alloy (HEA) electrode attractive candidate as cathode material in the water electrolysis for large-scale hydrogen production and suggest HEAs as ideal platform to develop multisite electrocatalysts.