A review of recent developments in green synthesis of TiO2 nanoparticles using plant extract: Synthesis, characterization and photocatalytic activity

[Display omitted] •Nanoparticles synthesized from plants are more stable and efficient than conventional synthesis technique.•Modern extraction methods for plants are superior to green synthesis of TiO2 compared to conventional extraction.•Alkoxy titanium precursor is preferable in the green synthesis of TiO2 because it often produces smaller sizes.•Green TiO2 NPs show reduced particle aggregation and addition of functional groups that support applications as catalysts.•TiO2 NPs as a photocatalyst for removing dye and antibacterial and antiviral activity are reviewed. Nanotechnology has a big role in current knowledge and technology. Apart from that, the need for the environmentally friendly and cheaper synthesis of nanoparticles is urgently needed. Titanium dioxide nanoparticles (TiO2 NPs) are used in various chemical, medical, and membrane technologies due to their self-cleaning, photocatalytic, and antibacterial properties. Conventionally synthesized TiO2 NPs use chemicals that cause biological risks due to their toxicity. Therefore, serious attention is needed to synthesize environmentally-friendly TiO2 NPs. This paper aims to explain the latest research on green chemistry in the synthesis of titanium dioxide nanoparticles using various plant extracts. It has been found that nanoparticles synthesized from plants are much more stable and efficient. Secondary metabolites from plant extracts, which mostly consist of polyphenols, are known to play a role in the formation of nanoparticles. An overview of various extraction techniques, synthesis, mechanisms, and characterization techniques is discussed from the latest literature. Applications of photocatalysis such as organic pollutants removal, antibacterial, and antiviral properties are also explained in detail. This review concludes with challenges and possible future aspects of TiO2 NPs for various environmental applications.