Mechanistic Investigation of Alkali-Treated Photocatalytic CO Reduction: The Role of OH and Metal Cations for Almost 100 % Selectivity of CO.

In this work, the modulation of activity and selectivity via photoreduction of carbon dioxide under simulated sunlight was achieved by treating P25 and P25/Pt NPs with KOH. It found that KOH treatment could significantly improve the overall conversion efficiency and switch the selectivity for CO. Photoelectric characterizations and CO -TPD demonstrated that the synergistic effect of K and OH accelerated the separation and migration of photogenerated charges, and also improved CO adsorption level. Significantly, the K ions could act as active sites for CO adsorption and further activation. In situ FTIR measurements and DFT calculations confirmed that K enhanced the charge density of adjacent atoms and stabilize CO* groups, reducing the reaction energy barrier and inducing the switching of original CH to CO, which played a selective regulatory role. This study provides insights into the photocatalytic activity and selectivity of alkali-treated photocatalysts and facilitates the design of efficient and product-specific photocatalysis.