Integrative Chemistry-Based Generation of Novel Three Dimensional Macrocellular Carbonaceous Biofuel Cell
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Integrative Chemistry-Based Generation of Novel Three Dimensional Macrocellular Carbonaceous Biofuel Cell
Victoria Flexer, Nicolas Brun, Mathieu Destribats, Rénal Backov and Nicolas Mano Centre de Recherche Paul Pascal, UPR 8641-CNRS, Université de Bordeaux, 115 Avenue Albert Schweitzer, 33600 Pessac, France. ABSTRACT Here we report the first membrane-less biofuel cell made by using three-dimensional carbonaceous foam electrodes. We first developed a new synthetic pathway to produce a new carbonaceous foam electrode material with increased porosity both in the meso and macroporous scale. We proved that by increasing the porosity of our three-dimensional foams we could increase the current density of our modified electrodes. Then, by choosing the right combination of enzyme and mediator, and the right loading of active components, we achieved unprecedentedly high current densities for an anodic system. Finally, we combined the improved cathode and anode to build a new membrane-less hybrid enzymatic biofuel cell consisting of a mediated anode and a mediator-less cathode. INTRODUCTION Enzyme based biofuel cells convert chemical to electrical energy employing enzymes as biocatalysts, with promising advantages in terms of cost, simple construction, renewable catalysts and fuels, while operating in mild conditions [1]. Enzymatic biofuel cells have been proposed for applications in niche areas of power generation such as implantable medical devices, or portable electronic devices under specific conditions, such as remotely located, or devices needing a non-toxic fuel [2]. Today enzymatic biofuel cells are still limited by both lifetime (due to enzyme denaturation and desorption), and lower power densities that restrict their application [3-5]. Most biofuel cells described to date, involve the immobilization of enzymes on inert electrode materials such as glassy carbon. Beyond, carbonaceous materials, in different forms have been proposed as good candidates because of high surface area and good mass transport, in addition to being chemically stable and biocompatible. In this view, our group is among the firsts to have pioneered the idea of using three-dimensional electrodes for the construction of biofuel cells, as it is already common practice in classical fuel cells[3-5]. Large multidirectional pores in the micrometer scale are needed for efficient fuel delivery to comply with the high demand of substrate of high enzymatic activity. On the other end, smaller pores, in the tenth of nanometer scale are needed to allow for the large surface area that will maximize enzyme loading. Moreover, if the right nanoporisity is chosen, enzyme molecules will then be more efficiently trapped in the porous structure, avoiding loss of catalysts, while keeping their activity [3,5]. The chemical functionalization of electrode materials, and the electrode roughness in the sub-nanometer scale, will both help to stabilize the enzyme and serve as anchoring sites. Eventually they will help the direct electron transfer (DET) from the enzyme to t
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