Oxidative Depolymerisation of Kraft Lignin: From Fabrication of Multi‐Metal‐Modified Electrodes For Vanillin Electrogeneration via Pulse Electrolysis To High‐Throughput Screening of Multi‐Metal Composites

Abstract

Abstract The production of green hydrogen may be greatly aided by the use of an alternative anode reaction replacing oxygen evolution to increase energy efficiency and concomitantly generate value‐added products. Lignin, a major component of plant matter, is accumulated in large amounts in the pulp and paper industry as waste. It has excellent potential as a source of aromatic compounds and can be transformed into the much more valuable aroma chemical vanillin by electrochemical depolymerisation. We used a flow‐through model electrolyser to evaluate electrocatalyst‐modified Ni foam electrodes prepared by a scalable spray‐polymer preparation method for oxidative lignin depolymerisation. We demonstrate how pulsing, i. e. continuously cycling between a lower and a higher applied current, increases the amount of formed vanillin while improving the energy efficiency. Further, we present a scanning droplet cell‐assisted high‐throughput screening approach to discover suitable catalyst materials for lignin electrooxidation considering that a suitable electrocatalyst should exhibit high activity for lignin depolymerization and simultaneously a low activity for vanillin oxidation and oxygen evolution. Combining electrosynthesis and electrocatalysis can aid in developing new customised materials for electrochemical processes of potential industrial interest.

Keywords

• electrocatalytic lignin oxidation
• non-noble active anodes
• flow-through cell
• pulse electrolysis
• performance screening