Controlling Radical Pathways via Valence Engineering of Rh/TiO₂ for Selective Jet Fuel Synthesis from Biomass.

Abstract

Photocatalytic biomass conversion offers a sustainable route for jet fuel production under mild conditions, while controlling the selectivity of products remains a long-standing challenge because of the involvement of various radical intermediates. Herein, we report a strategy to achieve selective switching toward jet fuel (C₈-C₁₈ hydrocarbons) in the photocatalytic decarboxylation of biomass-derived fatty acids by regulating hydrogen radical transfer on TiO₂ surfaces. By modulating the valence states of Rh cocatalysts, we spatially orient radical intermediates to guide their reaction pathways: oxidized Rh (Rh³⁺) promotes decarboxylative hydrogenation (yielding C_<i>n</i>-1 alkanes), while reduced Rh (Rh⁰) drives decarboxylative C-C coupling (forming C_2<i>n</i>-2 alkanes). This approach enables selective conversion of a broad range of biomass-derived acids, including fatty acids, aromatic acids, branched-chain fatty acids, and naphthenic acids, into target jet fuel hydrocarbons. This work provides an effective strategy for directing reaction pathways through spatial control of radical intermediates, advancing the development of sustainable biomass upgrading technologies.