▎ 摘　　要

Graphene oxide (GO) was applied for construction of an effective biocathode based on bilirubin oxidase (BOD). Separation of small-sized GO sheets together with the BOD immobilisation protocol has detrimental effects on the bioelectrocatalytic reduction of oxygen. When BOO was deposited on electrochemically reduced GO (ErGO) only a negligible current density j = 2.6 mu A cm(-2) was observed. Current density dramatically increased to a value of 46 mu A cm(-2) once BOD was in-situ mixed with as-received GO directly on a glassy carbon electrode (GCE) with subsequent electrochemical reduction of the BOD/GO composite. When this protocol was tested with small-sized GO flakes separated simply using centrifugation, the fabricated biocathode exhibited j = 120 mu A cm(-2). A current density further increased to j = 280 mu A cm(-2) when BOD and purified GO were incubated ex-situ for 4 h, followed by the BOD/GO composite collection by centrifugation, its deposition on the GCE and electrochemical reduction. Moreover, oxygen reduction current increased steeply with a steady-state current density achieved at high potential (approximate to 500 mV), close to the onset potential of oxygen reduction (approximate to 580 mV). (C) 2014 Elsevier B.V. All rights reserved.