The electrochemical oxidation of butanediol isomers in an alkaline direct liquid fuel cell

In this work we demonstrate the first alkaline direct liquid fuel cell powered by butanediol (BD), and we examine the difference in performance and product formation across the four linear isomers 1,4-BD, 1,3-BD, 1,2-BD, and 2,3-BD when oxidation of the BD occurs on a Pd/C catalyst. The highest maximum power density was observed with the 1,4-BD isomer, reaching as high as 157 mW cm−2 at 60 °C using a split pH fuel cell. Both the fuel cell and the electrochemical cell showed an order of performance (i.e., power density and current density, respectively): 1,4-BD > 1,3-BD > 1,2-BD > 2,3-BD, with variations in performance dependent on the technique chosen. Carbon NMR was performed on fuel cell products to determine that the vicinal diols (1,2-BD and 2,3-BD) oxidized through some C–C bond scission, while the other isomers only oxidized at 1 or 2 of the alcohol groups. Overall, this work demonstrates potential for very strong power from a BD fuel cell. Furthermore, this work also presents an analysis of how the relative position of the alcohol groups impacts the adsorption of the molecule on the Pd surface leading to different performance levels and product formation.