(584ev) Synthesis and Evaluation of TiO2/CdS Nanocomposite for Photocatalytic Degradation of Acetaminophen under Sunlight Activation

Due to its photo stability, abundance, low cost, and strong oxidative potential, titanium dioxide (TiO₂) has been most widely studied semiconductor photocatalyst and therefore, has been popularly used for various applications, especially for degradation of organic contaminants from water. However, due to its limited activation to visible light, the modification strategies have been sought to enhance photocatalytic efficiency in visible light region. In this contribution, TiO₂/CdS nanocomposites were synthesized in two molar ratios, 1:1 and 1:0.5 through a controlled chemical precipitation method to investigate their photocatalytic performance in the degradation of acetaminophen, an emerging water and wastewater pollutant and a common antipyretic and analgesic pharmaceutical. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to validate the crystal structures, chemical bonding, and surface morphology of TiO₂/CdS nanocomposites for visible light absorption.

Photocatalytic degradation experiments were conducted under three experimental conditions using ambient natural sunlight irradiation for 7 hours in sunny day in May of 2024: (i) control sample under sunlight without catalyst, (ii) pure TiO₂ under sunlight, and (iii) 1:1 TiO₂/CdS nanocomposite under sunlight. In the absence of a catalyst, little degradation of 7.58% was observed. Pure TiO₂ demonstrated only a little increase photocatalytic activity of 12.05% degradation under visible sunlight, attributed to its wide bandgap and rapid electron-hole recombination. Notably, the 1:1 TiO₂/CdS nanocomposite achieved an enhanced degradation of 27.32% within the 7 hours of experiments conducted between 11 am to 6 pm. This enhancement in the degradation can be ascribed to the formation of a heterojunction between TiO₂ and CdS, which facilitated an improved visible light absorption and a better charge separation.

The finding shows TiO₂/CdS nanocomposite as a potential system for efficient and effective sunlight-driven photocatalysts for the advanced oxidative degradation of water/wastewater pharmaceutical contaminants.