Improved photoelectrochemical water oxidation kinetics using a TiO 2 nanorod array photoanode decorated with graphene oxide in a neutral pH solution

We prepared TiO2 nanorod (NR) arrays on a fluorine-doped tin oxide substrate and decorated with graphene oxide (GO) to study their photoelectrochemical (PEC) water oxidation activities in two different electrolytes. The PEC performances of GO-decorated TiO2 NR photoanodes were characterized by optical and electrochemical impedance spectroscopy measurements. In 1 M KOH, the photocurrent density of the TiO2 NR film decreased after deposition of GO, while in the neutral pH electrolyte (phosphate buffered 0.5 M Na2SO4), the TiO2 NR photoanode showed enhanced performance after deposition with the 2 wt% GO solution. This was a consequence of the decrease in charge transfer resistance between the electrode surface and the electrolyte. The improvement of photocurrents by GO decoration was obvious near the onset potential of the photocurrents in the neutral pH electrolyte. These opposite contribu…