Lignin oxidative depolymerization and simultaneous hydrogen production – utilization of a photoelectrochemical cell (PEC)

As Net Carbon Zero and the development of the circular economy become critical global environmental issues, developing alternative green energy resources for fossil fuels are an area of significant research activity. Bioenergy is potentially one of the most promising green energy resources due to the large annual global output lignocellulosic biomass originated from forestry and agricultural residues[1]. Methods such as fermentation, gasification, catalytic decomposition etc.,[2] have been utilized in biorefinery and green hydrogen production applications. One of the main components of lignocellulosic biomass - lignin, however, is the largest naturally renewable source of aromatic compounds[3]. Currently this material is most commonly incinerated as decomposition, because this material is challenging due to the cross-linked bonding between cellulosic monomers. This is approach not only has a carbon foot print but also is a loss of a potentially high value raw material. Methods for the highly selective conversion of lignin into aromatic high-value chemicals, consequently needs to be urgently investigated. Consequently in this research, NiTi-type LDH with synthetic cationic vacancies[4] is used as a photocatalyst for the oxidative depolymerization of lignin in a PEC as a photoanode, while hydrogen is produced at the photocathode. The device is capable of both lignin valorization and green hydrogen production to provide green energy, solving the problem of high anode overpotential in photoelectrolysis of water.