Tuning the interfacial electric field via potential-zero-charge engineering for boosted alkaline hydrogen evolution

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Water dissociation is the rate-limiting step in alkaline hydrogen evolution reaction (HER).
• The interfacial electric field significantly influences water dissociation kinetics.
• Precise control over the interfacial electric field for HER enhancement remains a challenge.

Purpose of the Study:

• To develop a molecular modification strategy for tuning the interfacial electric field.
• To utilize the potential of zero charge (PZC) as a descriptor for modulating interfacial properties.
• To enhance the alkaline HER performance of CoS2 catalysts.

Main Methods:

• Molecular modification of CoS2 using pyridine sulfonic acid.
• Potential-dependent surface charge analysis to determine PZC shifts.
• In situ Raman spectroscopy to probe interfacial water behavior.
• Density functional theory (DFT) calculations to investigate reaction mechanisms.

Main Results:

• Pyridine sulfonic acid anchored onto CoS2, inducing interfacial charge redistribution and a positive PZC shift of 40 mV.
• Observed changes in water vibrational modes indicate a reorganized hydrogen-bond network.
• DFT calculations confirmed a reduced water dissociation barrier from 0.73 to 0.51 eV.
• The modified CoS2 catalyst achieved an ultralow overpotential of 23.3 mV at 10 mA cm-2 and a reduced Tafel slope of 54.6 mV dec-1.

Conclusions:

• The potential of zero charge (PZC) is an effective descriptor for regulating interfacial electric fields.
• Molecular modification strategy successfully enhanced the alkaline HER performance.
• This approach offers a new pathway for designing efficient electrocatalysts for hydrogen production.