Efficient photoelectrochemical CO2 conversion for selective acetic acid production

Amidst the development of photoelectrochemical (PEC) CO2 conversion toward practical application, the production of high-value chemicals beyond C-1 compounds under mild conditions is greatly desired yet challenging. Here, through rational PEC device design by combining Au-loaded and N-doped TiO2 plate nanoarray photoanode with Zn-doped Cu2O dark cathode, efficient conversion of CO2 to CH3COOH has been achieved with an outstanding Faradaic efficiency up to 58.1% (91.5% carbon selectivity) at 0.5 V vs. Ag/AgCl. Temperature programmed desorption and in situ Raman spectra reveal that the Zn-dopant in Cu2O plays multiple roles in selective catalytic CO2 conversion, including local electronic structure manipulation and active site modification, which together promote the formation of intermediate *CH2/*CH3 for C-C coupling. Apart from that, it is also unveiled that the sufficient electron density provided by the Au-loaded and N-doped TiO2 plate nanoarray photoanode plays an equally important role by initiating multi-electron CO2 reduction. This work provides fresh insights into the PEC system design to reach the multi-electron reduction reaction and facilitate the C-C coupling reaction toward high-value multicarbon (C2+) chemical production via CO2 conversion. (C) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

This study achieves efficient conversion of CO2 to acetic acid by rational PEC device design, revealing the important role of Zn doping in Cu2O for selective catalytic CO2 conversion, and uncovering the equally crucial role of Au-loaded and N-doped TiO2 in initiating multi-electron CO2 reduction.