Dynamic restructuring of nickel sulfides for electrocatalytic hydrogen evolution reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Transition metal chalcogenides are promising electrocatalysts for hydrogen evolution.
• Understanding active sites and mechanisms in alkaline media is crucial but challenging.

Purpose of the Study:

• To elucidate the active sites and catalytic mechanism of NiS during the hydrogen evolution reaction in alkaline media.
• To investigate the in-situ phase transition of NiS under operando conditions.

Main Methods:

• Operando X-ray absorption spectroscopy (XAS).
• Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS).

Main Results:

• NiS undergoes an in-situ phase transition to a mixed phase of Ni3S2 and NiO.
• Synergistic dual active sites are generated at the Ni3S2/NiO interface.
• Interfacial Ni and S sites are identified for water dissociation/OH* adsorption and H* adsorption/H2 evolution, respectively.
• Achieved low overpotential of 95 ± 8 mV at 10 mA cm⁻².

Conclusions:

• The dynamic chemistry of transition metal chalcogenides allows for in-situ formation of highly active catalytic species.
• Controlling working conditions can optimize electrocatalyst performance through phase engineering.