Chemical Modifications of Ag Catalyst Surfaces with Imidazolium Ionomers Modulate H₂ Evolution Rates during...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Optimizing electrochemical reactors is crucial for energy and sustainability.
• Polymer design and catalyst surface science interactions can tune reactor performance.
• Organic-inorganic interfaces influence reaction selectivity and activity.

Purpose of the Study:

• Investigate imidazolium-based ionomers' role in electrocatalytic CO2 reduction to CO (CO2R) on silver surfaces.
• Understand how ionomers affect CO2R and the competing hydrogen evolution reaction (HER).
• Determine the impact of ionomer structure on catalytic activity.

Main Methods:

• Electrocatalytic experiments measuring CO2R and HER rates.
• Kinetic modeling based on varying CO2 and bicarbonate (HCO3-) concentrations.
• Analysis of ionomer structure-activity relationships using Taft steric parameters.
• Density functional theory (DFT) calculations.

Main Results:

• Imidazolium ionomers showed no effect on CO2R activity on Ag surfaces.
• Ionomers strongly promoted the competing HER.
• Kinetic modeling indicated intrinsic promotion of HCO3- reduction by ionomers.
• Varying ionomer structure modulated HER promotion, with steric bulk limiting the effect.

Conclusions:

• Steric hindrance in ionomer structure restricts interaction with the catalyst surface and substrates.
• Findings provide design rules for ionomer-catalyst interactions in CO2R.
• Further research is needed to understand coordination effects in electrocatalysis.