Revisiting Laccase Modified Electrodes for Oxygen Cathodes

M. GRATTIERI; CALVO EJ,; CATHERINE ADAM; PABLO SCODELLER; FEDERICO WILLIAMS

Malmo

Simposio; XXIII International Symposium on Bioelectrochemistry and Bioenergetics; 2015

Bioelectrochemical Society

Laccase (EC1.10.3.2) is a blue copper extracellular enzyme in plants and fungi which catalyzes the oxidation of biphenols and the reduction of O2.1 It contains 4 Cu atoms: T1, T2 and T3. High potential T1 can be reduced by artificial mediators or undergo direct electron transfer. Further intramolecular ET to the T2/T3 tri-nuclear cluster results in O2 reduction. Laccase has been extensively studied as a catalyst in O2 cathodes both for direct electron transfer (DET)2 and mediated electron transfer (MET) 3-6 using a redox shuttle to the T1 site. In most previous studies it has been assumed that O2 is reduced to 2 H2O molecules from the mechanistic studies of Solomon.7 However, in 2010 Scodeller showed for the first time that osmium mediated laccase O2 cathodes produced hydrogen peroxide which also inhibits the enzyme.8 This was further confirmed by the group of Minteer.9 We will present new experimental evidence on the inhibition of H2O2 both in DET and MET laccase electrodes using LbL Os polymer mediator with Trametes Trogii highly purified laccase at well characterized electrodes.1.E. I. Solomon, U. M. Sundaram and T. E. Machonkin, Chemical Reviews, 1996, 96, 2563-2605.2.C. F. Blanford, R. S. Heath and F. A. Armstrong, Chemical Communications, 2007, 1710-1712.3.J. W. Gallaway and S. A. C. Barton, Journal of the American Chemical Society, 2008, 130, 8527-8536.4.N. Mano, V. Soukharev and A. Heller, Journal of Physical Chemistry B, 2006, 110, 11180-11187.5.V. Soukharev, N. Mano and A. Heller, Journal of the American Chemical Society, 2004, 126, 8368-8369.6.F. Barrière, Y. Ferry, D. Rochefort and D. Leech, Electrochemistry Communications, 2004, 6, 237-241.7.E. I. Solomon, P. Chen, M. Metz, S. K. Lee and A. E. Palmer, Angewandte Chemie - International Edition, 2001, 40, 4570-4590.8.P. Scodeller, R. Carballo, R. Szamocki, L. Levin, F. Forchiassin and E. J. Calvo, Journal of the American Chemical Society, 2010, 132, 11132-11140.9.R. D. Milton and S. D. Minteer, J. Electrochemical Society, 2014, 161, H3011-H3014.