Hybrid catalyst cascade for enhanced oxidation of glucose in glucose/air biofuel cell

Hybrid enzymatic and organic catalyst cascade system for enhanced glucose oxidation is proposed and utilized to fabricate glucose/air enzymatic biofuel cells. The presence of bifunctional TEMPO improves the energetic efficiency, thus boosting the cell performance. [Display omitted] •A hybrid enzymatic and organic catalyst cascade for glucose oxidation is proposed.•The organic catalyst catalyzes 4e- oxidation of glucose into glucuronic acid.•The organic catalyst is capable of mediating electron transfer between enzymes and electrode.•Feasibility of using the hybrid catalyst cascade in glucose/air biofuel cell is demonstrated. Redox enzymes are capable of harvesting electrical energy from biofuels in high catalytic activity and under mild condition. However, it is difficult to achieve efficient electron transfer and deep oxidation of biofuels simultaneously in a single-enzyme catalytic system. Herein, we report a hybrid catalyst cascade consisting of an organic oxidation catalyst, 2,2,6,6-tetramethyl-1-piperidine N-oxyl (TEMPO), and an enzyme, glucose oxidase (GOx), for electrochemical oxidation of glucose. It is found that TEMPO is capable of mediating electron transfer between the redox center of GOx and the electrode surface. While glucose can be oxidized into glucuronic acid under neutral conditions. Thus, combining GOx and TEMPO, we are able to achieve 4e- electrooxidation of glucose using the hybrid enzymatic and organic cascade (HEOC) system. When coupled with an air-breathing Pt cathode, the resulting glucose/air biofuel cell using the proposed HEOC anode exhibits a maximum power density of 38.1 μW cm−2 with a short-circuit current of 651.4 μA cm−2, which can be attributed to the enhanced energetic efficiency, enabling TEMPO a promising catalyst for glucose oxidation in bioelectronics applications.