Enhancing Efficiency and High-Value Chemicals Generation through Coupling Photocatalytic CO 2 Reduction with Propane Oxidation.

Conversion of CO 2 into high-value chemicals using solar energy is one of promising approaches to achieve carbon neutrality. However, the oxidation of water in the photocatalytic CO 2 reduction is kinetically unfavorable due to multi-electron and proton transfer processes, along with the difficulty in generating O-O bonds. To tackle these challenges, this study investigated the coupling reaction of photocatalytic CO 2 reduction and selective propane oxidation using the Pd/P25 (1 wt%) catalyst. Our findings reveal a significant improvement in CO 2 reduction, nearly fivefold higher, achieved by substituting water oxidation with selective propane oxidation. This substitution not only accelerates the process of CO 2 reduction but also yields valuable propylene. The relative ease of propane oxidation, compared to water, appears to increase the density of photogenerated electrons, ultimately enhancing the efficiency of CO 2 reduction. We further found that hydroxyl radicals and reduced intermediate (carboxylate species) played important roles in the photocatalytic reaction. These findings not only propose a potential approach for the efficient utilization of CO 2 through the coupling of selective propane oxidation into propylene, but also provide insights into the mechanistic understanding of the coupling reaction.