External abiotic glucose fuel cells

The advantages of the use of glucose as a fuel in low-temperature fuel cells are its abundance, easy availability, low cost, non-toxicity and no storage problems. Renewable biomass resources, including starch and cellulose, can be readily converted to the glucose molecule with little energy cost. This overview is focused on abiotic external glucose fuel cells (GFCs), presenting an appreciable performance (maximum power density ≥ 0.1 mW cm−2). Various types of traditional acid and alkaline fuel cells, using solid catalysts, have been fueled with glucose. A comparison of traditional fuel cells fueled with low molecular weight compounds and glucose showed that GFCs have a considerably lower performance, due to partial glucose oxidation, with formation of gluconic acid, by releasing only two electrons, so there is still much room for their improvement. A new type of fuel cells, using liquid catalysts instead of solid catalysts, have recently aroused great interest. When used as a fuel in liquid catalyst fuel cells (LCFCs), glucose provides better cell performance than more simple fuels. In LCFCs glucose can be more deeply oxidized, up to CO2. The hydroxyl/carbon number of polyhydric alcohols seems to be the key factor that determines the LCFC performance, indicating that higher polyhydric compounds, such as glucose, are more suitable fuels for LCFCs than simple alcohols.