The aim of this project is to manufacture an enzymatic biocathode using a laccase that catalyzes the reduction of oxygen to water. In-house produced and purified Laccase from T. versicolor has been selected due to its stability and high redox potential. The laccase was immobilized by covalent bonding (NHS/EDC method) or by adsorption on the functionalized surface of an electrode. The laccase activity in presence of ABTS and the current output without a mediator were evaluated. The direct electron transfer (DET) was achieved between the electrode and the immobilized laccase. To functionalize the carbon electrode surfaces, two functionalization approaches have been investigated. Firstly, the electrodes surfaces were electrochemically functionalized with amine or carboxylic groups using diazonium salt. The laccase was then covalently immobilised on carboxylic functionalised surfaces. Dioxygen reduction was performed by DET and a current density of 25,1±6,1 µA∙cm-2 was obtained. Using an oxidized laccase improved the biocathode performance and allowed to reach a current density of 166,8±21,4 µA∙cm-2. Secondly, for the first time the plasma treatment approach as an innovative, simple and rapid strategy for the chemical functionalization of graphite carbon electrodes was studied. Different plasma parameters were investigated. Depending on the plasma type (air, O2 and N2), carboxylic, carbonyl and amine/amide functionalities were generated. Dioxygen reduction was also performed by DET. The highest current density of 108 µA∙cm-2 was recorded for covalently immobilized laccase on N2 plasma treated surfaces
