Electro-catalytic oxidation of cellulose at Au electrode

Ari Ivaska, Yasuhito Sugano, Rose-Marie Latonen, Marceline Akieh and Johan Bobacka

Process Chemistry Centre, Åbo Akademi UniversityBiskopsgatan 8, FI-20500 Turku, Finland

ACES: European Dimension21.5. 2015

ChemSusChem, 2014, 7, 2240-2247

Molecular structure of cellulose

Polysaccharide: β(1→4) linked D-glucose units

Insoluble in pure water but can be dissolved in 1.3 M NaOH

CVs of cellulose at Au electrode in 1.3M NaOH

CVs of cellulose at Au electrode in 1.3M NaOH

CVs of cellulose at Au electrode in 1.3M NaOH

CVs of cellulose at Au electrode in 1.3M NaOH

CVs of cellulose at Au electrode in 1.3M NaOH

Mass change during potential cycling in1.3 M NaOH

Scan rate 10 mV/s

Sample treatment

Electrolysis

Original cellulose sample (solid)

Dialysis

Centrifugation

Water insoluble fraction

Water soluble fraction

Dialysis

Centrifugation

Cellulose solution sample (liquid)

Water insoluble fraction

Water soluble fraction

Dissolution in 1.3 M NaOH

Vacume-freeze-drying

Vacume-freeze-drying

SEM images of cellulose samples

original regenerated water insolubleafter electrolysis

water solubleafter electrolysis

TEM images of water-insoluble cellulose after electrolysis

Au nanoparticles ≈ 4 nm

Proposed mechanism

a: initial state: dissolved cellulose in alkaline solutionb: adsorption of OH- ions to the electrode and cellulose molecule approaching the Au-OH site on the electrode surfacec: oxidation of cellulose at the electroded: simultaneous desorption of the oxidation product from the surface and further oxidation of cellulose at the revealed electrode surfacee: desorption of adsorbed OH- ions from the electrode surface.

Conclusions

Cellulose can be oxidized at Au surface Adsorption of OH- ions at the Au surface is of

importance Two type of material is formed during

electrolysis:

- water soluble: containing caboxyl groups

- water insoluble: containing Au nanoparticles

Electroanalysis in Ireland, Electroanalysis na h’Éireann

NIHE, 10-12.6.1986

Meeting in Dublin 5.5.2014

Previous arrival to Dublin

ICSM-2014, Turku, Finland

Thank you for your attention

CVs of 1 % cellulose solution in 1.3 M NaOH

Different potential ranges