Anna Inzenhofer: Waste-derived photoelectrodes

Environmental issues, especially increased CO₂ emissions, have led to changes in industrial practices towards a future electrified society and away from fossil fuels. As such, the use of bio-based materials (EU Bioeconomy Strategy), as well as the efficient use of the critical metals (EU Critical Raw Materials Act), for example platinum-group metals, is timely and  pertinent to this green transition.

Lignin, an aromatic biomacromolecule, is mainly considered a by- product of the pulp and paper industry and burnt for fuel. Lignin-based carbon fibers have been prepared from various spinning techniques - melt spinning, electrospinning and wet-spinning, however oftentimes these methods rely on expensive or toxic, aprotic solvents. Concerted efforts by the bioproducts community have already resulted in the successful utilization of lignin as fibrous material for gas diffusion electrodes, battery anodes, proton exchange membranes, and supercapacitors. 

This project focuses on a less energy-intensive method of producing lignin-based carbon fibers, solution-blown spinning. Various forms of lignin are being explored – including high molecular weight lignin, Kraft lignin, as well as acetone-soluble lignin. Furthermore, we aim to combine the fields of materials science and hydrometallurgy by using the lignin-derived electrodes for metal recovery using a pulsing technique called electrochemical deposition redox replacement (EDRR), to recover low amounts of Pd from cupric chloride solutions that resemble real hydrometallurgical process streams.