Effects of deposition time on the photoelectrochemical properties of gold nanoparticles decorated titanium dioxide nanotubes

The use of nanostructured solar cells has gained much interest as a new and promising alternative in harvesting solar energy. Solar-driven energy conversion process such as photoelectrochemical (PEC) water splitting has been proven to be a renewable and environmentally friendly energy conversion method, with metal oxides such as TiO2 as the preferable photoanode. This is due to its stability, non-toxic as well as low cost and exhibits strong photocatalytic activity [1]. However, TiO2 possesses a large bandgap of 3.2eV (anatase) which only allows it to be reactive under UV light. Thus, in this study, gold nanoparticles were deposited onto the TiO2 nanotubes (TNT) in order to extend its spectral response to the visible range. In this study, gold decorated titanium dioxide nanotubes (AuTNT) were fabricated by pulse electrodeposition method. The electrodeposition time was varied from 10-30 mins with a fixed duty cycle of 75% at 0.7V in 0.1M H2SO4 containing the 100µM gold solution. The physicochemical properties of AuTNT were characterized by EDX and XRD. The band gap of the AuTNT was determined by UV-DRS and photoelectrochemical properties of the AuTNT were measured in 0.1M Na2SO4 and 2M C2H5OH under illumination of a halogen lamp. The deposition of gold nanoparticles on the TiO2 nanotubes was able to decrease its band gap energy to 2.6 eV. The AuTNT prepared within 30 minutes deposition time resulted in the highest photocurrent compared to other deposition times.