Boosted photocatalytic CO₂ reduction through interface engineering by constructing CdS-MnO₂ heterojunction

To mitigate the levels of CO₂ in the atmosphere, photocatalytic conversion of CO₂ into hydrocarbons presents a viable approach. Herein, a CdS-MnO₂ composite synthesized through a facile electrostatic self-assembly method was employed as an effective catalyst for photocatalytic CO₂ reduction. The engineered CdS-MnO₂ minimized the recombination of photogenerated electrons and holes, thereby facilitating the charge transfer and boosting the catalytic activity of pristine CdS. The introduction of NaOH solution into the reaction environment further enhanced the interfacial electron transfer and increased the affinity to the key intermediate *CO, facilitating additional multielectron reactions for methanol production. The alkaline characteristics of NaOH solution not only promotes the adsorption and activation of inert CO₂ molecules, but also function as hole scavengers, significantly reducing the photogenerated carrier recombination and further promoting the CO₂ reduction, especially in multielectron reactions towards methanol. A notable yield of 13.4 μmol g⁻¹ h⁻¹ for methanol and 7.6 μmol g⁻¹ h⁻¹ for CO was obtained with the CdS-MnO₂. The results obtained herein may provide insights into the design of a highly efficient photocatalytic systems aimed at converting CO₂ into higher value-added products.