Ultrasonic-Assisted Fabrication of TiO2-Based Composite Photocatalysts for Enhanced Photocatalysis of Organic Pollutants: A Review

Water contamination and the global energy crisis are two of the most significant challenges in the world. Titanium dioxide (TiO2) has garnered attention due to its promising photocatalytic performance. However, its wide band gap energy limits its efficiency under visible light irradiation. To address this, TiO2-based composite photocatalysts have been developed to narrow the band gap energy and suppress the recombination of electron–hole pairs, thereby enhancing photocatalytic performance. The ultrasonic technique, through acoustic cavitation, facilitates a synthetic process involving localized transient high-pressure and high-temperature conditions to produce photocatalysts with superior photocatalytic capabilities. This review focuses on ultrasonication and ultrasonic-assisted fabrication method for modifying TiO2 into visible light-driven composite heterostructures. It discusses the parameters of ultrasonication that influence the synthesis and modification of these composites, along with the factors affecting photocatalytic performance.