Accelerating hydrogen evolution at neutral pH by destabilization of water with a conducting oxophilic metal oxide

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 8; no. 24; pp. 12169 - 12176
• Main Authors: Xie, Zhengzhe, Wang, Wugang, Ding, Ding, Zou, Yu, Cui, Yi, Xu, Lai, Jiang, Jiang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 28.06.2020
• Subjects: Adsorbed water; Density functional theory; Destabilization; Electrical conductivity; Electrical resistivity; Electrochemistry; Electrolysis; Energy of dissociation; Hydrogen; Hydrogen evolution reactions; Hydrogen production; Hydroxides; Interfaces; Metal oxides; Nanostructure; pH effects; Recombination; Seawater; Vanadium; Vanadium oxides; Wastewater
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d0ta04241b

Electrolysis in neutral media is vital for cost-efficient hydrogen production utilizing vast resources like wastewater and seawater. However, the required high overpotential remains an enormous obstacle, which is due to the sluggish water dissociation Volmer step along with the subsequent proton recombination step. Herein, choosing strongly oxophilic and metallic vanadium sesquioxide (V 2 O 3 ) as the water dissociation center, we present the synthesis of self-supporting Ni 4 Mo-V 2 O 3 nanosheets via topotactic transformation of oxometallate intercalated layered double hydroxide (LDH). Benefiting from their good electrical conductivity, large electrochemical surface area, exposed active sites and abundant heterogeneous interfaces, Ni 4 Mo-V 2 O 3 nanosheets exhibit an extremely low overpotential of 39.3 mV at 10 mA cm −2 and a Tafel slope of 65.7 mV dec −1 for the hydrogen evolution reaction (HER) at neutral pH. Density functional theory calculations confirm that V 2 O 3 on Ni 4 Mo alloy enhances water adsorption and reduces the energy barriers for water dissociation, as well as the subsequent H 2 generation, thus achieving superior HER performance in neutral electrolyte. Self-supporting Ni 4 Mo-V 2 O 3 nanosheets, which combine oxophilic V 2 O 3 as a water dissociation center with Ni 4 Mo as a proton recombination site, display an extremely low overpotential (39.3 mV at 10 mA cm −2 ) for hydrogen evolution at neutral pH.