Enhanced Proton Spillover at Pt-Cluster/NiO Interface Reduces the Acidic-Alkaline Hydrogen Evolution Activity Gap

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• The hydrogen evolution reaction (HER) is sluggish in alkaline media due to water dissociation kinetics, creating an activity gap compared to acidic conditions.
• Metal-supported catalysts utilizing hydrogen spillover show promise, but understanding and controlling spillover mechanisms for active catalyst design remains challenging.

Purpose of the Study:

• To develop an efficient electrocatalyst for alkaline HER by engineering oxygen defects in NiO nanowires.
• To investigate the role of oxygen defects in facilitating hydrogen spillover and enhancing HER activity.

Main Methods:

• Fabrication of platinum nanoclusters (PtNC) on oxygen-defect-rich NiO nanowires (PtNC-D-NiO).
• Electrocatalytic activity testing for HER in alkaline media.
• Advanced in situ/operando characterizations, including electrochemical impedance spectroscopy, to analyze defect effects.

Main Results:

• The PtNC-D-NiO electrocatalyst exhibited superior intrinsic and mass-normalized HER activity and stability compared to controls and commercial Pt/C.
• Alkaline HER activity of the new catalyst approached that under acidic conditions, significantly reducing the activity gap.
• Oxygen defects were shown to lower the water dissociation energy barrier, promoting H* spillover and recombination.

Conclusions:

• Oxygen-rich NiO nanowires provide an effective platform for enhancing alkaline HER through improved hydrogen spillover.
• The developed catalyst offers a cost-effective strategy and fundamental insights into optimizing electrocatalytic performance via defect engineering.