Fabrication, characterization and photoelectrochemical properties of cuprous oxide-reduced graphene oxide photocatalysts for hydrogen generation

Abstract

Reduced graphene oxide protected Cu2O/Cu foil (rGO/Cu2O/Cu foil) photocathodes have been synthesized via a two-step strategy. (NH4)2S2O8 was first used to oxidize Cu foil and prepare Cu(OH)2 nanostructures/Cu foil. In the second step, graphene oxide (GO) solution and the prepared Cu(OH)2/Cu foil sample were hydrothermally reacted in a Teflon lined stainless steel autoclave for different periods of time at 120 °C, followed by calcination at 450 °C under N2 atmosphere for 3 h. The effect of modification of rGO on the photoelectrochemical activity of different rGO/Cu2O/Cu foil samples has been studied by FESEM, XRD, FTIR, Raman spectroscopy and UV–Vis diffuse reflectance spectroscopy. Continuous and transparent layer of GO sheets are formed on the surface of Cu(OH)2 nanostructures/Cu foil, according to FESEM results. The photoelectrochemical properties of the prepared samples in the dark and under illumination conditions were investigated using linear sweep voltammetry and chronoamperometry techniques. The rGO/Cu2O/Cu foil photocathodes exhibit enhanced photocurrent density under illumination (85 mW/cm2) in comparison with the bare Cu2O/Cu foil photocathode. The improved separation efficiency of photogenerated charge carriers may be mainly accounted for this enhanced photoelectrochemical performance. A low photostability of 12.5% of the initial photocurrent density was observed for the bare Cu2O/Cu foil photocathode after 1000s of illumination whereas this value reached to almost 77% after modification of rGO. The new rGO/Cu2O/Cu foil nanocomposite prepared in this study is believed to be a promising photocathode material in photoelectrochemical cells for efficient water splitting.