New insights into the role of CO2 in a photocatalytic fuel cell

The objective of this work is to explore the role of CO 2 in the photocatalytic fuel cell with TiO 2 as the photoanode and methanol as a fuel under acid condition by making the anode electrolyte saturated with CO 2 . It is interesting to find that the performance of the photocatalytic fuel cell can be improved at low methanol concentration in the presence of CO 2 . This is probably because TiO 2 has an adequate conduction band for photocatalytic reduction of CO 2 to organics at the photoanode, which increases the methanol concentration at the catalytic surface to alleviate the mass transfer issue encountered in the low methanol concentration operation, and hinders the recombination of the electron-hole pairs. Moreover, the methanol concentration at the outlet of the photoanode can be even higher than the supplied methanol concentration. However, this effect is weakened and even disappears as the supplied methanol concentration increases. This work gives new insights into the role of CO 2 in the photocatalytic fuel cell with the photoanode having an adequate conduction band for photocatalytic reduction of CO 2 .