Kraft lignin as dispersing agent for carbon nanotubes

Kraft lignin (KL) was found to undergo strong adsorption on multi-walled carbon nanotubes (MWCNT) from aqueous/organic solutions. The MWCNT/KL composite could be re-dispersed in dimethyl sulfoxide to form a relatively stable suspension. Films of MWCNT/KL could then be obtained using this suspension in the casting method. A strong interaction of MWCNT and KL was confirmed by Raman spectroscopy. The adsorbed lignin served also as a redox polymer and the composite modified electrode after initial electrooxidation showed characteristic redox functions assignable to KL-derived quinone moieties. The redox activity of the MWCNT/KL composite could be employed to electrocatalyse the oxidation of dihydronicotinamide adenine dinucleotide (NADH) in a nearly neutral (pH 7.4) buffer or the reduction of iodate in acidic (pH 1.8) electrolyte.