Photoelectrocatalytic production of hydrogen peroxide using a photo(catalytic) fuel cell

[Display omitted] •Photoelectrocatalytic production of hydrogen peroxide using a Photo Fuel Cell.•Unbiased operation simply by shining light.•A visible light responsive photoanode made by a CdS/TiO2 combination.•Cathode made by depositing carbon black on carbon cloth.•Substantial photogenerated current thanks to current doubling phenomena. Photoelectrochemical production of hydrogen peroxide has been studied by using a two-compartment photoelectrochemical cell operating in the Photo(catalytic) Fuel Cell mode, i.e. it run without any external bias, simply by shining light and generating current. The photoanode was made of CdS quantum dots deposited on nanocrystalline titania, which was first formed on a transparent fluorine doped tin oxide electrode. The photoanode operated in an alkaline environment with added ethanol as model fuel. An air-breathing cathode was made by depositing carbon black on carbon cloth, without any additives of particular functionalities. Best results were obtained by using a neutral electrolyte (Na2SO4) in the cathode compartment. Hydrogen peroxide was produced during cell operation in a cumulative manner adding up to 1400 mg/l (41 mM) in three hours of operation. The rate of hydrogen peroxide production during this period of time remained practically constant and was 5.7 μmole/min, which corresponds to an average Faradaic efficiency of 74%. These data characterize a system with satisfactory performance that may be used for solar fuel production.