Spin-Coated Nanostructured Tungsten Oxide (WO₃) Thin Films for Photocatalytic Degradation of Organic Dyes: A Comprehensive Review
Author : Prafulla S. Patil
Abstract :
The rapid release of colored waste water, which is typically contaminated with synthetic organic dyes from the textile, paper, leather, pharmaceutical, and printing industries, is a significant threat to the environment. These dyes can be toxic and persist in the environment. A viable solution to address these threats includes using semiconductor photocatalysis, as it is a method that is highly effective, safe to the environment and sustainable. Several photocatalytic materials have been studied; however, among them, tungsten oxide (WO3) is one of the most attractive due to its relatively narrow band gap energy (1.23 eV), good chemical stability, visible light photoactivity, and low toxicity. Spin coated nano-structured WO3 thin films are being widely investigated because they provide advantages such as low production costs, high uniformity of the thin films deposited onto substrates with controlled thickness and scalability to large area substrates. This article provides a thorough analysis of developments of spin-coated nanostructured WO3 thin films based on photocatalytic degradation of organic dyes. The crystalline structures, optical properties, electronic characteristics, photocatalytic processes and other critical factors that affect the performance of WO3 thin films were analyzed. Modifications to increase the photocatalytic efficiency included metal or non-metal doping, hetero-junction formation, defect engineering and plasmonic enhancements that facilitate charge separation and enhance photocatalytic activities under visible light illumination. Finally, comparative studies regarding the degradation efficiencies of representative organic dyes (such as methylene blue, rhodamine B, methyl orange, and Congo Red) were reviewed. Furthermore, the main challenges that need to be addressed in order to develop stable long-lasting photocatalysts at large scales, while suggesting potential areas for future investigation on multi-functional coatings and solar driven photocatalytic systems.
Keywords :
Tungsten oxide (WO₃), Spin coating, Thin-film photocatalyst, Nanostructured materials, Photocatalysis, Organic dye degradation, Visible-light photocatalysis, Wastewater treatment, Semiconductor photocatalysts, Environmental remediation.
