Visible light-driven self-heating photocatalytic decarboxylation of fatty acid over α-Fe2O3

Abstract

Here we report a temperature-dependent strategy that achieves high-efficiency photocatalytic decarboxylation of long-chain fatty acids to Cn-1 n-alkanes, e.g., producing ∼0.5 M of n-heptadecane from stearic acid in a single operation with ∼91% selectivity, far beyond no more than mM limit capacities of conventional photocatalysis. Through the use of high boiling-point n-alkane solvents for getting the best self-heating based on the photothermal conversion effect of α-Fe2O3, i.e., high temperatures, which force the standing C-chain at low temperatures down onto the α-Fe2O3 surface for energy-storing, allowing photo-induced hole-electron pairs to readily approach and react with the more strained C-COO- bonds. And the consumption of photogenerated electrons shifts from the conventional PCET of the photo-Koble reaction into a step-wise pathway to form more favorable carbanion intermediate that reacting with H+ into RH is accelerated with lifting temperature. Our work offers a practical approach to upgrade photocatalytic decarboxylation by a convenient photo-to-heat route.