Ultra-Small Gold Nanoclusters in Efficient Biofuel Cell Design

Energy security is one of the most pressing challenges in the world that need to be addressed through fundamental scientific research. With sources of fossil fuels dwindling, there is an urgent need to find cheap and renewable forms of energy using naturally abundant resources such as sunlight, air, and water. Nanostructured materials and enzymatic fuel cells are showing great promise in alternative energy conversion. 1 The cathodic oxygen reduction reaction (ORR) is a technologically important reaction in the process of energy production. One of the limiting factors that dictate the performance of enzymatic electrodes towards ORR is the slow rate of electron transfer (ET) at the enzyme-electrode interface. 2 Therefore, efficient ET is needed to lift this critical methodological barrier in biofuel cells design. Few atom ultra-small metal nanoclusters (<2nm in diameter) possess many interesting properties compared to bulk metals owing to their discrete electronic states distribution. In this talk I will discuss synthesis and characterization of a new DNA-templated gold nanocluster (AuNC) of ~1 nm in diameter and possessing ~7 Au atoms. When integrated with bilirubin oxidase (BOD), an enzyme used for cathodic ORR in biofuel cells, and carbon nanotubes (CNTs) as a support material, the AuNCs act as remarkable enhancer of ET for ORR by lowering the overpotential for the electrocatalytic ORR by ~15 mV compared to BOD alone. This unique property of AuNCs as ET enhancer at the enzyme-electrode interface makes them potential candidates for development of cathodes in enzymatic fuel cells and removes a critical technological barrier in biofuel cell design. 3