Review on tungsten trioxide as a photocatalysts for degradation of recalcitrant pollutants

Recently, the increasing level of water pollution worldwide has not only contributed to environmental issues, but also triggered considerable interest in photocatalysis that act as promising wastewater treatment. Among the explored photocatalysts, tungsten trioxide (WO3) known for its extraordinary characteristics for photocatalytic degradation applications, such as photostability, high crystallinity with high yield and recyclability, inexpensiveness, and photo-corrosion resistance. However, critical issues of high-risk method for inefficient photonic and quantum, and their insignificant structure would lead to recombination of photogenerated carriers, which diminishes photocatalytic efficiency; this is deemed to be a major hurdle to the widespread application of WO3. As a solution, the objective of this review was representing the interpretation several scopes of WO3-based photocatalyst such as the introduction of its basic principles, significant each different precursor, synthesis methods, numerous types of modifications, influential operating parameter and their pro and cons into a photocatalytic system under irradiation. This significant scope could be done to further increase their activity level that attracted much attention in many published studies between year 2010 and 2020. Although energy storage mechanism of photocatalyst is still at an embryonic stage, studies have suggested for the development of photocatalyst with great potential and high rate of degradation. The interesting and unique features of tertiary composites of WO3-based photocatalyst are found to be more effective for photocatalytic degradation due to their more efficient absorption band, band gap, and surface area, as compared to binary and unitary. The enhanced photocatalytic capabilities of WO3-based photocatalyst with their different significant parameters are reviewed towards various pollutant removal, such as synthetic wastewater and real industrial wastewater, among others. Finally, the benefits with ongoing challenges of WO3 are proposed with the aim to improve the design of a highly efficient WO3-based photocatalyst.