A Mediator-Free Multi-ply Biofuel Cell Using an Interfacial Assembly between Hydrophilic Enzymes and Hydrophobic Conductive Oxide Nanoparticles with Pointed Apexes.

Biofuel cells (BFCs) based on enzymatic electrodes hold great promise as power sources for biomedical devices. However, their practical use has been hindered by low electron transfer efficiency and poor operational stability of enzymatic electrode. Here, we present a novel mediator-free multi-ply BFC that overcomes these limitations and exhibits both substantially high-power output and long-term operational stability. Our approach involves the utilization of interfacial interaction-induced assembly between hydrophilic glucose oxidase (GOx) and hydrophobic conductive indium tin oxide nanoparticles (ITO NPs) with distinctive shapes, along with a multi-ply electrode system. For the preparation of anode, GOx and oleylamine-stabilized ITO NPs with bipod/tripod type were covalently assembled onto the host fiber electrode composed of multi-walled carbon nanotubes and gold nanoparticles (Au NPs). Remarkably, despite the contrasting hydrophilic and hydrophobic properties, this interfacial assembly approach allows for the formation of nanoblended GOx/ITO NP film, enabling efficient electron transfer within the anode. Additionally, the cathode was prepared by sputtering Pt onto the host electrode. Furthermore, the multi-ply fiber electrode system exhibited unprecedented high-power output (∼10.4 mW cm -2 ) and excellent operational stability (2.1 mW cm -2 , ∼49% after 60 days of continuous operation). Our approach can provide a basis for the development of high-performance BFCs. This article is protected by copyright. All rights reserved.