A study on tandem photoanode and photocathode for photocatalytic formaldehyde fuel cell

We report a fuel cell device with double-side semiconductor photoelectrode, in which TiO2 nanorods (NRs) array serves as photoanode for formaldehyde oxidation, and Cu2O photocathode takes part in oxygen reduction reaction (ORR). Unlike traditional noble metal-based fuel cells, the whole fuel cell reaction is operated from photoelectrocatalytic process due to photogenerated holes and electrons. The best performance is obtained by photoexciting both TiO2 photoanode and Cu2O photocathode through contrast experiments, the short circuit current and open circuit voltage of the fuel cell reach 1.2 mA/cm2 and 0.58 V, respectively. Mott-schottky measurement, surface photovoltage (SPV) transients and linear sweep voltammetry (LSV) test under illumination further reveal the thermodynamic and dynamic feasibility for charge transfer in the formaldehyde oxidation-oxygen reduction process. This study introduces an alternative design in developing non-noble metal photocatalytic fuel cells with low cost and high practicality.