Mechanistic Investigation of Alkali-Treated Photocatalytic CO 2 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 2 -TPD demonstrated that the synergistic effect of K + and OH - accelerated the separation and migration of photogenerated charges, and also improved CO 2 adsorption level. Significantly, the K ions could act as active sites for CO 2 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 4 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.