High-power “nesting-doll” biofuel cell enabled by free-standing electrodes with inherent enzymatic function

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Biofuel cell (BFC) is a type of green energy device based on the biocatalyst-mediated redox reaction. However, their relatively low performance has limited their wider application. Here, we proposed a novel all-in-one strategy to design the free-standing electrodes with the inherent enzyme-like activity and high conductivity, in which, the dynamic limitations of the enzyme-electrode interface were eliminated. This approach facilitated rapid electron transfer by removing the need to coat enzymes on the electrode. Furthermore, the enzyme-mimic characteristic enhanced the stability of BFC. Notably, the step-by-step “ionic corrosion-electrografting coordination” of Cu foam yielded the free-standing cathode, which exhibited excellent laccase-like activity. Concurrently, the in-situ loading of gold particles on the Ni foam can serve as an exemplary mimic of the glucose oxidase. Furthermore, a “nesting doll” nanozyme BFC device was developed, in which, the anode was placed inside the cathode to create a multi-shell coaxial configuration. The four-tier devices demonstrated an elevated open-circuit voltage of 1.7 V, and the output power density was 3639.0 μW cm⁻2 measured by resistance method, which was superior to that of the reported literatures. This study presents a pioneering approach to improving output performance and stability, thereby broadening the potential scope of BFC application.