Chemically reduced graphene oxide-P25-Au nanocomposite materials and their photoelectrocatalytic and photocatalytic applications.

Visible light active photocatalysts consisting of gold nanoparticle (Au NP) decorated chemically reduced graphene oxide-P25 nanocomposite materials (CRGO-P25-Au NCMs) were prepared through a one-pot chemical reduction method. The nanocomposite materials were characterized using diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and electrochemical impedance spectroscopy (EIS) analyses. The performances of CRGO-P25-Au NCM modified ITO electrodes were evaluated towards the photoelectrochemical oxidation of methanol. The photoelectrode fabricated using CRGO-P25-Au NCM exhibited a higher photocurrent of 293 μA cm-2 compared to other control electrodes. The CRGO-P25-Au NCMs were also used for the photocatalytic reduction of highly toxic chromium(vi) ions to chromium(iii) ions in the presence of oxalic acid as a sacrificial electron donor. The results showed that around 75% of the Cr(vi) ions were photocatalytically reduced to Cr(iii) ions by the CRGO-P25-Au NCM within the light irradiation time of 1 h. In both applications, the enhanced catalytic activity of the CRGO-P25-Au NCM was attributed to the improved visible light absorption and the reduced charge recombination exerted by the interaction of CRGO and Au NPs with P25 and their synergistic effects.