Efficient photoelectrochemical CO conversion for selective acetic acid production.

Amidst the development of photoelectrochemical (PEC) CO conversion toward practical application, the production of high-value chemicals beyond C compounds under mild conditions is greatly desired yet challenging. Here, through rational PEC device design by combining Au-loaded and N-doped TiO plate nanoarray photoanode with Zn-doped CuO dark cathode, efficient conversion of CO to CHCOOH 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 CuO plays multiple roles in selective catalytic CO conversion, including local electronic structure manipulation and active site modification, which together promote the formation of intermediate *CH/*CH for C-C coupling. Apart from that, it is also unveiled that the sufficient electron density provided by the Au-loaded and N-doped TiO plate nanoarray photoanode plays an equally important role by initiating multi-electron CO 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 (C) chemical production via CO conversion.