Nanomaterials have many applications in a variety of sectors including drug delivery systems, disease diagnosis, biosensors, cancer biology, pollution control, hydrogen generation, battery-supercapacitors, energy, cosmetics, and agriculture. Nanometal oxides possess unique characteristics due to their large surface area-to-volume ratio and unusual catalytic activity, electronic properties, optical properties, and antimicrobial activity. Different types of nanoparticles can be synthesized using various methods. Nanometal oxide nanomaterials are multifunctional in nature with versatile physical and chemical properties. They have recently gained great significance due to the easy tunability of their electrical, chemical, optical, thermal, and mechanical properties by altering morphological and microstructural features.

Currently, the green synthesis of nanometal oxides has received significant attention in the fields of environmental nanotechnology and bio-nanotechnology. As compared to chemical and physical methods of synthesis, the synthesis of nanoparticles using green materials is more environmentally friendly, cost-effective, and avoids the use of toxic chemicals. There is a better opportunity for green synthesis of nanometal oxides using plants, bacteria, algae, and fungi. Suspension of bacterial culture, extract of plant secondary metabolites, extract of secondary metabolites, and extract of fungus are the main components of the green synthesis of nanometal oxides. Different types of nanometal oxides mainly including transition metal oxides such as titanium dioxide, copper oxide, zinc oxide, cerium dioxide, chromium dioxide, molybdenum trioxide, silver oxide, cobalt oxide, and iron oxide have various applications associated with the environment.

Thus, in order to highlight the latest developments in the field of synthesis and multifunctional applications of nanometal oxides, this Special Issue aims to solicit original research and review articles that highlight current research relevant to environmental and biomedical applications of nanometal oxides.

Potential topics include but are not limited to the following:

• Green approaches for nanometal oxides synthesis
• Recent advancements and challenges of nanometal oxides and their applications
• Green technologies for the biosynthesis of nanometal oxides and their applications for environmental sustainability
• Green nanometal oxides and their biomedical applications
• Photocatalytic applications of green synthesised nanometal oxides
• Green synthesis of nanometal oxides and their biomedical applications
• Green synthesis of nanoparticles from microbes and their prospective applications
• Biomedical applications of algal synthesised nanometal oxides
• Plant-derived synthesis nanometal oxides and their biomedical applications
• Biosynthesis and characterisation of nanometal oxides
• Toxicity analysis of nanometal oxide
• Fungal synthesis of nanometal oxides and their applications
• Degradation of dyes using green synthesised nanometal oxides
• Catalytic activities of green nanometal oxides
• The application of nanometal oxides in pollutant remediation