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

Abstract

The research of a robust catalytic system based on single NiO electrocatalyst for hydrogen evolution reaction (HER) remains a huge challenge. Particularly, the factors that dominate the catalytic properties of NiO-based hybrids for HER have not been clearly demonstrated. Herein, a convenient protocol for the fabrication of NiO@bamboo-like carbon nanotube hybrids (NiO@BCNTs) is designed. The hybrids exhibit superb catalytic ability and considerable durability in alkaline solution. A benchmark HER current density of 10 mA cm 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 Ni ratio and the Ni on the interface of Ni/NiO play a vital role in the outstanding catalytic performance. Especially, the Ni on the interface of Ni/NiO performs superior activity for water splitting compared with that of bulk Ni. These conclusions provide guidance for the rational design of the future non-noble metallic catalysts.

Ni@NiO Nanowires on Nickel Foam Prepared via “Acid Hungry” Strategy: High Supercapacitor Performance and Robust Electrocatalysts for Water Splitting Reaction

“…Meanwhile, more unfilled d orbitals in Ni 2+ will strengthen such kind of electrostatic effect in comparison with Ni 0 . Furthermore, given the ideal hydrogen adsorption energy of Ni 0 , H ads will prefer to adsorb on Ni 0 sites at the Ni/NiO interface . The presence of Ni metal before and after test was confirmed by X‐ray diffraction (XRD) in Figure S16 (Supporting Information).…”

Electrocatalysts for Hydrogen Evolution in Alkaline Electrolytes: Mechanisms, Challenges, and Prospective Solutions

“…The as‐prepared hybrid nanostructures exhibited good HER performance with a overpotential of 300 mV at 10 mA cm −2 and a small Tafel slope (110 mV dec −1 ), which is ascribed to the enhanced density of electron transfer at specific domains caused by the defective sites on DG. Currently, heteroatom‐doped graphitic carbon materials have been applied in HER as well because of their large specific surface area and unique electronic properties 126. Bamboo‐like nitrogen‐doped carbon nanotube based nickel oxide (NiO x @BCNT) hybrid was designed through calcination of melamine/Ni(NO 3 ) 2 ·6H 2 O (Figure 8b,c).…”

“…Inset in part (e) is the fast Fourier transform (FFT) images of Ni o . Reproduced with permission 126. Copyright 2016, American Chemical Society.…”

NiO as a Bifunctional Promoter for RuO2 toward Superior Overall Water Splitting

“…According to previous studies, individual NiO bind OH too strongly, leading to a higher overpotential for the OER . Due to the strong adsorption of OH, it has appreciable capability for water dissociation, but its unfavorable hydrogen adsorption limits the alkaline HER activity . Interestingly, fruitful synergy is expected to achieve superior overall water electrolysis through hybridizing NiO with RuO 2 .…”