Implanting Ni-O-VOx sites into Cu-doped Ni for low-overpotential alkaline hydrogen evolution

Abstract

Nickel-based catalysts are most commonly used in industrial alkaline water electrolysis. However, it remains a great challenge to address the sluggish reaction kinetics and severe deactivation problems of hydrogen evolution reaction (HER). Here, we show a Cu-doped Ni catalyst implanted with Ni-O-VOx sites (Ni(Cu)VOx) for alkaline HER. The optimal Ni(Cu) VOx electrode exhibits a near-zero onset overpotential and low overpotential of 21 mV to deliver-10 mA cm −2 , which is comparable to benchmark Pt/C catalyst. Evidence for the formation of Ni-O-VOx sites in Ni(Cu)VOx is established by systematic X-ray absorption spectroscopy studies. The VOx can cause a substantial dampening of Ni lattice and create an enlarged electrochemically active surface area. First-principles calculations support that the Ni-O-VOx sites are superactive and can promote the charge redistribution from Ni to VOx, which greatly weakens the H-adsorption and H 2 release free energy over Ni. This endows the Ni(Cu)VOx electrode high HER activity and long-term durability.

Metal–Sulfur Linkages Achieved by Organic Tethering of Ruthenium Nanocrystals for Enhanced Electrochemical Nitrogen Reduction

“…However, the inert nature of N 2 and intensive competition from hydrogen evolution reaction (HER) impede its performance with sluggish kinetics and low selectivity. [3][4][5][6][7] Ru-based transition metal catalysts are active catalysts for NRR at ambient conditions that can activate and polarize the inert N 2 molecule by accepting and donating electronic density. [8][9][10][11] However, they are limited by the low selectivity and faradaic efficiency (FE) towards NH 3 that could be attributed to the high affinity of H-adsorption on the Ru surface.…”

Design and operando/in situ characterization of precious‐metal‐free electrocatalysts for alkaline water splitting

“…62 Most recently, Zhao and co-workers fabricated Cu-doped Ni catalysts with implanted Ni-O-VO x composites (Ni(Cu)VO x ) via a facile electrodeposition approach as highly efficient HER catalysts. 59 The optimized Ni(Cu)VO x outperformed most precious-metal-free HER catalysts reported so far, with an extremely low overpotential of merely 21 mV to deliver 10 mA cm −2 . The enhanced HER activity originated from the optimal ΔG H* and H 2 release free energy, owing to the superactive Ni-O-VO x sites which promote the charge redistribution from Ni to VO x ( Figure 5A-C).…”

“…100,149,161 The enhanced HER activity can also be achieved by metal doping because of the enhanced electron interactions and optimal ΔG H* during HER process. 59,62,162 For example, 3D hierarchical Cudoped porous Ni catalyst (Ni(Cu)/NF) exhibited satisfying catalytic activity toward HER because of the lattice distortion of Ni and the formation of NiO/Ni with increased interfacial activities. 62 Most recently, Zhao and co-workers fabricated Cu-doped Ni catalysts with implanted Ni-O-VO x composites (Ni(Cu)VO x ) via a facile electrodeposition approach as highly efficient HER catalysts.…”

“…Moreover, incorporating less stable elements such as Al and Zn cation as a sacrificial agent can create surface defects with the exposure of more low‐coordinated metal sites by selective removal of the dopants, which in turn improves the catalytic performance 100,149,161 . The enhanced HER activity can also be achieved by metal doping because of the enhanced electron interactions and optimal ΔG H* during HER process 59,62,162 . For example, 3D hierarchical Cu‐doped porous Ni catalyst (Ni(Cu)/NF) exhibited satisfying catalytic activity toward HER because of the lattice distortion of Ni and the formation of NiO/Ni with increased interfacial activities 62 .…”

“…C, The deformation electronic density of V‐Ni (111), yellow and cyan represent electron‐rich and electron‐deficient area. Reproduced with permission: Copyright 2020, Nature publishing group 59 . D, Schematic illustration for the synthesis of Ni‐N hybrid material.…”