High-Concentration Alkane Output via In Situ Thermal-Assisted Photocatalytic Decarboxylation of Biomass-Derived Fatty Acid

Production of alkane fuels from fatty acids by photocatalytic decarboxylation is presently challenging due to low product output efficiency. Here, we report a high-efficiency photocatalytic decarboxylation route, achieving the transformation of high-concentration bioderived long-chain fatty acids to C1-shortened n-alkanes only by using the in situ heat from the photothermal conversion of Fe₃O₄. Through the use of high-boiling-point n-alkane solvents for getting the maximum reaction temperature, the single output concentration of C_n–1 n-alkane was upgraded from a traditional far less than mmol/L level to the unprecedented mol/L level. We suggest that the heat enhances the strain of aimed C–COO^– bond by forcing the standing C-chain down at room temperature onto the Fe₃O₄ surface, leading photoinduced hole–electron pair easily to be close to and react with the energy-storing C–COO^– bond. Meanwhile, the photogenerated electron consumption can shift from conventional PCET of the photo-Koble reaction into a stepwise pathway to form a more favorable carbanion (R^–) intermediate that reacting with H⁺ into RH is highly accelerated with lifting the temperature. Our findings open a new way to upgrade the output efficiency of photocatalytic decarboxylation reaction by reusing the vast majority of incident light energy in a heat form.