Electrocatalytic lignin oxidation for hydrogen and fine chemical co-production using platinized nickel foam in a 3D printed reactor

Biomass electrooxidation has garnered much attention in recent years, owing to its potential to circumvent greenhouse gas emissions. Substituting the sluggish water oxidation with biomass oxidizable species such as lignin at anode is thermodynamically more favorable, enabling energy efficient hydrogen production and concomitant fine chemicals. The present study shows the organosolv lignin electrooxidation in an additively manufactured 3D printed reactor (3DPR) consisting of platinized nickel foam (PtNF) as anode and cathode and compared with commercial hardware electrolyzer (CHE). The electrolysis of organosolv lignin in 3DPR outperformed CHE by achieving 1.23 times higher current at an applied voltage range from 0 to 2.2 ​V with a membrane (Nafion 115) interposed between anode and cathode under a continuous flow of lignin feed at the anode. The chronoamperometry study reveals a mixture of diverse aromatic compounds, including vanillic acid, syringic acid, 3,5-dimethoxy-4-hydroxyacetophenone, 2-hydroxyacetophenone, 4-ethycathecol, and 2,6-dimethoxyphenol in anolyte, and sinapic acid and vanillin acetate in catholyte. Thus, realizing renewable biomass electrolysis in the 3DPR is an intriguing strategy for the co-production of hydrogen and fine aromatic chemicals.