The development of active hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) catalysts for use in anion exchange membrane fuel cells (AEMFCs), which are free from platinum group metals (PGMs), is expected to bring this technology one step closer to commercial applications. This paper reports our recent progress developing HOR Pt-free and PGM-free catalysts (Pd/CeO2 and NiCo/C, respectively), and ORR PGM-free Co3O4 for AEMFCs. The catalysts were prepared by different synthesis techniques and characterized by both physical-chemical and electrochemical methods. A hydrothermally synthesized Co3O4 + C composite ORR catalyst used in combination with Pt/C as HOR catalyst shows good H2/O2 AEMFC performance (peak power density of ~388 mW cm−2), while the same catalyst coupled with our flame spray pyrolysis synthesised Pd/CeO2 anode catalysts reaches peak power densities of ~309 mW cm−2. Changing the anode to nanostructured NiCo/C catalyst, the performance is significantly reduced. This study confirms previous conclusions, that is indeed possible to develop high performing AEMFCs free from Pt; however, the challenge to achieve completely PGM-free AEMFCs still remains.

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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.