Molecular Design Strategy in Dye-sensitized Photoelectrochemical Cells for the Lignin Oxidation

Abstract

Lignocellulosic biomass comprises lignin, cellulose, and hemicellulose and is the largest renewable carbon source on earth. The conversion of lignin represents an alternative to petroleum as a source for the production of aromatic compounds that serve as feedstocks for aviation fuels. The prospect of using lignin as a renewable and alternative source of aromatic compounds in place of petroleum has motivated several approaches for carrying out lignin depolymerization, but controlling the extent of the reaction to afford specific products remains a significant challenge. To overcome this issue, dye-sensitized photoelectrochemical cells have emerged for the visible-light-driven selective cleavage of the C–C/C–O bond in lignin model compounds at ambient temperature. However, these recent works have been limited to studying a relatively simple Ruthenium dye with limited tunable redox potentials. Compared with metal complexes like ruthenium dyes, the energy levels of organic dyes can be easily tuned by controlling donor–π–acceptor (D–π–A) configuration. This is because the organic dyes are designed with π-conjugated organic segments in a donor–π–acceptor (D–π–A) configuration, and their photophysical properties can be easily tuned by changing the molecular units. Especially, the controlling donor units in organic dyes are very important to study the mechanism of catalyzed cleavage of lignin. My group has studied organic dyes for over 10 years. In this presentation, I will present the molecular design strategy of controlling the donor energy level and the efficient charge transfer for photocatalytic oxidative C–C/C–O bonds cleavage in the DSPEC.