Promotion mechanism of nanomaterials and modified/combined nanomaterials on photodegradation of organic pollutants: a review based on meta-analysis.

An important method to degrade organic pollutants, such as dyes, drugs, toxic and persistent compounds is photodegradation. Innovative materials that are employed as catalysts in the photodegradation process are Nanomaterials (NMs). However, the high catalytic efficiency of single/traditional NMs (referred to as Simple NMs) often requires extreme reaction conditions, specific wavelengths of light, such as UV light, and auxiliary substances. This review finds that modified or combined NMs (called M/C NMs) can improve the photodegradation efficiency and maximum cycles of use of organic pollutants compared to Simple NMs through meta-analysis. Furthermore, this review also provides a comparison of Simple NMs and M/C NMs through meta-analysis to discuss their specific targets, effects of combinations or modifications, and the current challenges faced in the degradation of organic pollutants. This review highlights that M/C NMs can promote the absorption of organic pollutants and the excitation of photoelectrons due to improved band gaps, particle size, and structure, while requiring less stringent reaction conditions than Simple NMs. Even under visible light, M/C NMs can maintain higher degradation efficiency, achieving a 32.87 % reduction, compared to a 42.00 % reduction by Simple NMs. All NMs can achieve efficient photodegradation without the demand for an extreme pH environment or other common auxiliary substances, for example, HO. Therefore, NMs, especially M/C NMs, should be considered important catalysts and studied as potential research for the photodegradation of organic pollutants. Research on the prospects and sustainability of M/C NMs is presented based on the review results.