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_x electrocatalyst for hydrogen evolution reaction (HER) remains a huge challenge. Particularly, the factors that dominate the catalytic properties of NiO_x-based hybrids for HER have not been clearly demonstrated. Herein, a convenient protocol for the fabrication of NiO_x@bamboo-like carbon nanotube hybrids (NiO_x@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.