Synthesis of green TiO ₂ /ZnO/CdS hybrid nano-catalyst for efficient light harvesting using an elegant pulsed laser ablation in liquids method

The main limitation on the applications of TiO ₂ as a photocatalyst is its large band gap (3.2 eV) which limits its absorption only to the ultraviolet region of the solar spectrum. To overcome this problem, a facile strategy for clean synthesis of a nanocomposite green catalyst of zinc oxide (ZnO), titanium dioxide (TiO ₂ ) and cadmium sulphide (CdS) was developed using pulsed laser ablation in liquids (PLAL) technique for the first time to the best of our knowledge. The main aim of addition of ZnO is to reduce the electron-hole recombination in the TiO ₂ while CdS is used to increase the light harvesting efficiency of TiO ₂ in the visible spectral region. The absorption spectrum of the TiO ₂ /ZnO/CdS composite obtained from the UV-vis spectrophotometer exhibits strong absorption in the visible region as compared to the pure TiO ₂ whose absorption band lies around 380 nm which is in the UV-region. The morphology of the composite quantum dots was also investigated using high resolution TEM technique which shows that the synthesized composite size ranges between 10 and 40 nm. These nanocomposites have demosntarted noticible improvement in the carriers transport in the visible region which could enhance its efficiency for many applications in the visible region especially for energy harvesting using solar radiations.