Local Surface Structure and Composition Control the Hydrogen Evolution Reaction on Iron Nickel Sulfides

Area of Science:

• Materials Science
• Electrochemistry
• Surface Science

Background:

• Developing efficient electrocatalysts is crucial for energy applications, particularly for the hydrogen evolution reaction (HER) as an alternative to platinum.
• Understanding the relationship between surface structure, composition, and catalytic activity in abundant materials is key to designing next-generation catalysts.

Purpose of the Study:

• To investigate the nanoscale activity of Fe4.5Ni4.5S8, a promising HER catalyst, by probing its (111)-crystal planes.
• To correlate subtle compositional variations with differences in HER activity using advanced microscopy techniques.
• To establish design principles for rational synthesis of powerful electrocatalysts.

Main Methods:

• Scanning electrochemical cell microscopy (SECCM) was employed to map electrochemical activity at the nanoscale.
• Structural characterization methods were used in conjunction with SECCM.
• Electrochemical properties were probed at the nanoscale.

Main Results:

• SECCM successfully revealed variations in HER activity on the (111)-crystal planes of Fe4.5Ni4.5S8.
• Even minor compositional changes were found to significantly influence catalytic performance.
• A direct correlation between nanoscale surface structure/composition and HER activity was established.

Conclusions:

• Nanoscale electrochemical probing, combined with structural analysis, is a powerful approach for understanding catalyst behavior.
• This study provides insights into the rational design of highly active HER electrocatalysts based on abundant materials.
• The findings pave the way for developing novel, platinum-free catalysts for hydrogen production.