Viologen Catalysts for a Direct Carbohydrate Fuel Cell

Abstract

Deriving electrical energy from glucose and other carbohydrates under mild conditions is an important research objective because these biomolecules are abundant, renewable, have high energy density, and are convenient as fuels. This rich promise has not been realized because stable, inexpensive, and efficient catalysts are not available to oxidize carbohydrates and transfer all or nearly all of their electrons to fuel cell anodes. We report here that viologen catalysts meet these demanding criteria by catalytically oxidizing glucose and other carbohydrates in a mildly alkaline solution, making possible a direct carbohydrate fuel cell. Formate and carbonate are major products of carbohydrate oxidation, demonstrating that extensive carbon–carbon bond breaking has occurred. A rudimentary fuel cell utilizing viologen catalysts and glucose or dihydroxyacetone as fuels demonstrated electrical power production at up to superficial current density. Improved catalyst function and cell design should significantly advance the efficiency and viability of direct carbohydrate fuel cell technology as a means of generating electrical energy from renewable biomass.