Dominating Role of Ni⁰ on the Interface of Ni/NiO for Enhanced Hydrogen Evolution Reaction

The research of a robust catalytic system based on single NiO_<i>x</i> electrocatalyst for hydrogen evolution reaction (HER) remains a huge challenge. Particularly, the factors that dominate the catalytic properties of NiO_<i>x</i>-based hybrids for HER have not been clearly demonstrated. Herein, a convenient protocol for the fabrication of NiO_<i>x</i>@bamboo-like carbon nanotube hybrids (NiO_<i>x</i>@BCNTs) is designed. The hybrids exhibit superb catalytic ability and considerable durability in alkaline solution. A benchmark HER current density of 10 mA cm^–2 has been achieved at an overpotential of ∼79 mV. In combination with the experimental results and density functional theory (DFT) calculations, this for the first time definitely validates that the inherent high Ni⁰ ratio and the Ni⁰ on the interface of Ni/NiO play a vital role in the outstanding catalytic performance. Especially, the Ni⁰ on the interface of Ni/NiO performs superior activity for water splitting compared with that of bulk Ni⁰. These conclusions provide guidance for the rational design of the future non-noble metallic catalysts