Order-of-magnitude enhancement of an enzymatic hydrogen-air fuel cell based on pyrenyl carbon nanostructures

A fuel cell featuring two enzymes as electrocatalysts on specially modified electrodes-an O-2-tolerant hydrogenase for the anode and bilirubin oxidase for the cathode-produces more than 0.1 mW cm(-2) (electrode) at 1 V from a non-explosive hydrogen-air (80/20) mixture. The anode and cathode are prepared by covalently attaching the respective enzymes, via 1-pyrenebutyric acid functionalities, to multiwalled carbon nanotubes pre-coated on graphite. The fuel cell performance, which is limited by the reduction of O-2 (4%), represents an order-of-magnitude improvement over analogous cells in which the enzymes are conventionally adsorbed on graphite. These results bring forward realization of what is possible for niche devices able to generate small power outputs from gas mixtures under ambient conditions.