Efficient photoelectrochemical CO₂ conversion for selective acetic acid production.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Photoelectrochemical (PEC) CO2 conversion is crucial for sustainable chemical production.
• Producing high-value multicarbon (C2+) chemicals from CO2 under mild conditions remains a significant challenge.

Purpose of the Study:

• To develop an efficient PEC device for converting CO2 into high-value chemicals.
• To investigate the roles of specific material components in enhancing CO2 conversion selectivity and efficiency.

Main Methods:

• Fabrication of a PEC device using an Au-loaded and N-doped TiO2 plate nanoarray photoanode and a Zn-doped Cu2O dark cathode.
• Electrochemical characterization and analysis of CO2 conversion products, including Faradaic efficiency and carbon selectivity.
• Utilizing temperature programmed desorption and in situ Raman spectroscopy to understand catalytic mechanisms.

Main Results:

• Achieved efficient conversion of CO2 to acetic acid (CH3COOH) with a Faradaic efficiency of 58.1% and 91.5% carbon selectivity at 0.5 V vs. Ag/AgCl.
• Identified that Zn-doping in Cu2O modifies electronic structure and active sites, promoting C-C coupling via *CH2/*CH3 intermediates.
• Demonstrated that the photoanode provides sufficient electron density for multi-electron CO2 reduction.

Conclusions:

• The rational design of the PEC device, particularly the Zn-doped Cu2O cathode and the advanced photoanode, is key to selective CO2 conversion.
• This approach facilitates multi-electron reduction and C-C coupling, enabling the production of valuable C2+ chemicals from CO2.
• The findings offer insights into designing PEC systems for efficient and selective CO2 valorization.