Li sensitized CdS/TiO2 nanocomposite photoanode for solar water splitting, hydrogen generation and photoelectrochemical (PEC) performance

Li-CdS/TiO2 nanocomposite with different composition 10Li-CdS/TiO2, 20Li-CdS/TiO2, 30Li-CdS/TiO2, 40Li-CdS/TiO2, 50Li-CdS/TiO2 were coated on FTO surface by using doctor blade followed by successive ionic layer adsorption and reaction (SILAR) method. As synthesized Li-CdS/TiO2 photoanode is characterized with field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), diffuse reflectance spectroscopy (UV-DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). FE-SEM analysis suggests that, Li-CdS/TiO2 film is 10.2 mm thick, porous, spongy and uniformly covered on FTO surface. The HR-TEM images reveal that the CdS nanoparticles are in intimate contact with the TiO2 nanocrystal shells with the CdS/TiO2 interfaces and the particle size of CdS and Li2S lies in the range of 20 nm-50 nm. UV-DRS analysis shows that, as the loading of Li in CdS/TiO2 films increases, there is decrease in band gap energy. The XPS analysis sup-ports the presence of Li+ in Li-CdS/TiO2 nanocomposite. The PL spectra suggest that, with the increase in extend of Li+ ions into Li-CdS/TiO2, intensity of green emission band in-creases and it is shifted to higher wavelength. This reflects the low recombination rate of photo generated charge carrier in Li-CdS/TiO2 which is responsible for higher photo-catalytic H2 production. The visible light photoanodic performance of Li-CdS/TiO2 was investigated for H2 evolution using aqueous Na2SO3 and Na2S solution under natural sunlight. Among the all-synthesized nanocomposite material, the highest amount of hydrogen produced over 20Li-CdS/TiO2 was found to be 38.61 ml/g/h in natural sunlight. Photoelectrochemical (PEC) performance of Li-CdS/TiO2 was examined. A possible mechanism for photocatalytic hydrogen generation is also discussed.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.