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

Abstract

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.