Fabrication of palladium nanowire array electrode for biofuel cell application

a r t i c l e i n f o Keywords: Pd nanowires Nonenzymatic and enzymatic bioelectrocatalysis Glucose oxidase Biofuel cells Bioelectrocatalysis was demonstrated with palladium (Pd) nanowire array electrode via nonenzymatic and en-zymatic methods for glucose, which was validated by the generation of anodic current in the presence of glucose. The vertically standing Pd nanowires used for the fabrication of the electrodes were on average 5.6 μm in length and 64 nm in diameter. In comparison, the nonenzymatic bioanode exhibited lower current densities and required the application of larger overpotential which resulted in a large cell voltage drop (V oc = 13.5 mV) and limited power production when assembled as a biofuel cell under physiological conditions (pH 7, 0.1 M phosphate buffer saline) with laccase covalently bounded to Pd nanowires as the biocathode. The glucose/O 2 biofuel cell was studied in phosphate buffer saline using the enzymatic bioanode that was developed with the co-immobilization of catalase and glucose oxidase on Pd nanowires and the laccase-Pd as the biocathode. The biofuel cell exhibited an open-circuit voltage of 0.506 V, delivered a maximum power density of 72 μW cm −2 at a cell voltage of 0.25 V and a short-circuit current density of 411 μA cm −2 when operating in 10 mM glucose. Such low-cost lightweight glucose/O 2 biofuel cells have a great promise to be optimized, miniaturized to power bio-implantable devices. The resurgent development of biofuel cell devices has been driven by the mass-market acceptance of conventional fuel cell technologies, in which many efforts have been devoted to biocatalytically modified electrode materials, specifically for sensor applications [1–8]. These research activities in biocatalytically modified metal electrodes have provided a significant technological foundation for current biofuel cell development. Enzymatic biofuel cells employ biocatalysts to convert the chemical free energy stored in biofuels, such as glucose directly into bioelectricity. The generation of electricity is a product of the oxidation of the biofuel and the reduction of molecular oxygen by inexpensive biocatalysts. Researched biofuel cells employ direct electron transfer, as well as employ mediator electron transfer [9–15]. Katz et al. [12] studied the immobilization of a biocatalyst and a mediator at both the anode and cathode of an enzymatic fuel cell and showed that a maximal power density of 4 μW/cm 2 at a cell potential of 40 mV can be obtained by operating in 1 mM glucose (pH 7). Tsujimura et al. …