Detection of Lignin Motifs with RuO2-DNA as an Active Catalyst via Surface-Enhanced Raman Scattering Studies

Abstract

Biomass-derived lignin derivatives are significant biodegradable plant materials which produce a variety of value-added products by oxidation/oxidative cleavage methods. These value-added products constitute important materials for the sustainable production of biofuels. The ultralevel quantitative detection of feedstock carbonyls on metal surfaces is possible with surface-enhanced Raman spectroscopy (SERS) technique. Considering environmental friendly protocols for activation of molecular oxygen in both valorization methods of biomass, the corresponding SERS detection protocols are rare. Here, for the very first time, RuO2-DNA nanochains aggregate as an efficient catalyst for oxidation/oxidative cleavage of biomass-derived lignin mimics and their subsequent in-situ SERS detection. Notably, both reactions are carried out in aqueous medium. For the controlled oxidation study, veratryl alcohol and cinnamyl alcohol were used as lignin mimics, and the respective carbonyls were detected by the SERS method by activating molecular oxygen. Also, by changing the oxidant from molecular oxygen to peroxide, the respective acids were seen to be formed for veratryl alcohol. We extend this protocol to oxidative cleavage of lignin-derived olefins, and diols, such as cinnamyl alcohol and 1-phenyl-1,2-ethanediol, and corresponding acids were formed and detected by SERS technique. This oxidation protocol could also be scaled-up for large-scale synthesis and recyclability experiments to prove the robustness of the catalyst under green conditions.