Plasmon enhanced electrooxidation of ethanol using a new Au-Pt/TiO2/MWCNTs photoelectrocatalyst

A novel photoelectrocatalyst composed from multiwalled carbon nanotubes (MWCNTs), titanium dioxide (TiO2) and gold-platinum bimetallic nanoparticles (Au–PtNPs) was prepared on the surface of a fluorine-tin oxide (FTO) electrode and it was used for electrooxidation of ethanol molecules. Multiwalled carbon nanotubes were utilized as the catalyst support to improve the electrical transmission. The TiO2 nanoparticles were transferred onto the surface of MWCNTs/FTO modified electrode and then, the surface of the electrode was coated with gold-platinum nanoparticles. The surface morphology and chemical composition of the prepared Au-Pt/TiO2/MWCNTs photoelectrocatalyst were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. The fabrication process of the photoelectrocatalyst was investigated by cyclic voltammetry and chronoamperometry techniques. The exchange current densities (J0) were calculated for Pt/FTO, Pt/MWCNTs/FTO, Pt/TiO2/MWCNTs/FTO and Au-Pt/TiO2/MWCNT/FTO electrodes and they were found to be:  4.10 × 10-5, 6.06 × 10-5, 1.45 × 10-4 and 1.89 × 10-4 mA cm-2, respectively. Also, the values of J0 for Pt/TiO2/MWCNTs/FTO and Au-Pt/TiO2/MWCNTs/FTO in the presence of light were obtained 2.0 × 10-4 and 5.1 × 10-4 mA cm-2, respectively. The obtained results reveal that the Au-Pt/TiO2/MWCNTs/FTO electrode has the higher J0 value in the presence of UV-Vis light and the light irradiation can accelerate the ethanol oxidation process. The experimental results showed that the proposed photoelectrocatalyst has an excellent catalytic activity for oxidation of ethanol molecules under the UV-Vis light irradiation which is due to the synergistic effect between the TiO2 photocatalyst and gold-platinum electrocatalyst.