Tunable CO₂ electroreduction to ethanol and ethylene with controllable interfacial wettability

Area of Science:

• Electrochemistry
• Surface Science
• Catalysis

Background:

• The mechanism linking interfacial wettability to CO2 electroreduction pathways for ethylene and ethanol is not well understood.
• Controlling the balance of kinetically controlled intermediates, specifically carbon monoxide (*CO) and hydrogen (*H), is crucial for directing reaction selectivity.

Purpose of the Study:

• To investigate how interfacial wettability influences the electroreduction of carbon dioxide (CO2) to ethylene and ethanol.
• To design and implement a method for controlling the equilibrium of *CO and *H intermediates by modifying alkanethiols with varying alkyl chain lengths.

Main Methods:

• Modification of electrode surfaces with alkanethiols of different alkyl chain lengths to tune interfacial wettability.
• Electrochemical characterization and computational simulation to analyze mass transport and intermediate ratios.
• Systematic variation of interface from hydrophilic to superhydrophobic.

Main Results:

• Interfacial wettability affects the mass transport of CO2 and H2O, altering the ratio of *CO to *H intermediates.
• Shifting from hydrophilic to superhydrophobic interfaces changes the reaction limitation from *CO supply to *H supply.
• Achieved tunable ethanol to ethylene ratios from 0.9 to 1.92.
• Reached high Faradaic efficiencies for ethanol (up to 53.7%) and C2+ products (up to 86.1%).
• Demonstrated a C2+ Faradaic efficiency of 80.3% at a high partial current density of 321 mA cm⁻².

Conclusions:

• Modulating interfacial wettability provides a pathway to control CO2 electroreduction selectivity.
• The study reveals the significant role of wettability in managing intermediate ratios and product distribution.
• The developed strategy offers a promising approach for efficient and selective synthesis of valuable chemicals from CO2.