Evidence on C-C Coupling to Acetate as Key Reaction Intermediate in Photocatalytic Reduction of CO over Pt/TiO.

Photocatalytic conversion of CO with HO is an attractive application that has the potential to mitigate environmental and energy challenges through the conversion of CO to hydrocarbon products such as methane. However, the underlying reaction mechanisms remain poorly understood, limiting real progress in this field. In this work, a mechanistic investigation of the CO photocatalytic reduction on Pt/TiO is carried out using an operando FTIR approach, combined with chemometric data processing and isotope exchange of (CO + HO) toward (CO + HO). Multivariate curve resolution analysis applied to operando spectra across numerous cycles of photoactivation and the CO reaction facilitates the identification of principal chemical species involved in the reaction pathways. Moreover, specific probe-molecule-assisted reactions, including CO and CHCOOH, elucidate the capacity of selected molecules to undergo methane production under irradiation conditions. Finally, isotopic exchange reveals conclusive evidence regarding the nature of the identified species during CO conversion and points to the significant role of acetates resulting from the C-C coupling reaction as key intermediates in methane production from the CO photocatalytic reduction reaction.