CO₂ reduction efficiency through electrolyte immersion in hierarchical bismuth-nickel catalysts

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Nanostructures enhance electrolyte contact and catalytic efficiency for CO2 reduction reaction (CO2RR).
• Hydrophobicity of nanostructures can hinder electrolyte contact and complicate active area determination.
• Hierarchical catalysts offer potential for improved performance in CO2RR.

Purpose of the Study:

• To investigate the effect of electrolyte-catalyst contact area variation on CO2RR performance.
• To understand how immersion duration influences the efficiency of bismuth-nickel (BiNi) hierarchical catalysts.
• To optimize BiNi catalysts for enhanced formate production via CO2RR.

Main Methods:

• Fabrication of BiNi micro-nano hierarchical catalysts.
• Controlled pre-immersion of catalysts in an aqueous electrolyte for varying durations.
• Electrochemical characterization including cyclic voltammetry and chronoamperometry.
• Analysis of product selectivity and faradaic efficiency (FE%) for CO2RR.

Main Results:

• Pre-immersed BiNi catalysts demonstrated a 13.4-fold increase in formate production compared to pristine catalysts.
• A 2-day pre-immersed BiNi sample achieved ~80.1% FE% for formate and ~10% for H2 at -1.5 V vs. Ag/AgCl.
• Pristine BiNi catalysts showed lower FE% for formate (~12.9%) and higher for H2 (~76.3%) at a lower current density.

Conclusions:

• Pre-immersion significantly enhances the electrolyte-catalyst contact area.
• Improved contact through pre-immersion leads to superior CO2RR efficiency for formate production.
• Hierarchical BiNi catalysts are promising for efficient CO2 conversion to formate.