Improving the immobilization of glucose oxidase on carbon cloth via a hybrid approach of cross-linked chitosan/TPP matrices with Na® polymers for high-performance self-pumping enzyme-based biofuel cells

The real-world application of an enzyme-based biofuel cell (EBFC) requires the desirable immobilization of enzymes on the electrode surface, offering the feasibility of addressing its short lifetime and low-power density. Nevertheless, an efficient immobilization of enzymes strongly relies on the preferred scaffolding between the enzyme and the electrode. Accordingly, the development of a promising route to attain a tunable scaffold structure is urgently required. Herein, we present a facile and ecofriendly route for efficiently controlling the scaffold structure by investigating the interplay of tripolyphosphate (TPP), chitosan (CS), and Na. A series of glucose oxidase (GOx)-based anodic electrodes, GOx­[CS/TPP]­CC, GOx­[CS/Na]­CC, and GOx­[CS/TPP/Na]­CC, are synthesized using CS/TPP, CS/Na, and CS/TPP/Na as the scaffolding on carbon cloth (CC) followed by the immobilization of GOx for a comparative study of the microstructure, enzyme loading, and electrochemical property. It is revealed that the self-pumping EBFC, driven by capillary force, utilizing GOx­[CS/TPP/Na]­CC can deliver a higher peak power density (1.077 mW cm–2) than that utilizing GOx­[CS/TPP]­CC (0.776 mW cm–2) and GOx­[CS/Na]­CC (0.682 mW cm–2). The self-pumping EBFC utilizing GOx­[CS/TPP/Na]­CC can retain 89.2% of its beginning performance even after 240 h of testing, as compared with that utilizing GOx­[CS/Na]­CC (61.1%). This enhancement can be attributed to the formation of a desirable scaffold structure via the cross-linked CS/TPP matrices combined with Na polymers for the hybrid enzyme immobilization, simultaneously offering the capability of improving the enzyme-loading efficiency, facilitating the interaction between the surface electrode and the enzyme, and preventing the release of the enzyme during the cell operation.