Sustainable Nanotechnology

8 Green Synthesis of Titanium Dioxide Nanoparticles and Their Applications

Tabassum Siddiqui, Nida Jamil Khan, and Tasneem Fatma

Department of Biosciences, Jamia Millia Islamia, New Delhi, India

8.1 Introduction

Nanotechnology refers to the use of different methods and technologies aimed at obtaining materials with unique functions and properties [1]. Nanoparticles are the particles that possess size less than 100 nm and have greater surface‐to‐volume ratio (per unit mass) as compared to their non–nanoscale counterparts [2]. Increasing use of nanoparticles has led to continuously growing industrial, academic, and consumer interest in them. Unique surface chemistry and smaller size of nanoparticles are being utilized in the field of medicine, nutrition, and energy. Nanomaterials are referred as a wonder of modern medicine because they can kill upto 650 different disease‐causing organisms [3].

Titanium belongs to the family of transition metal oxides. It is a strong, lustrous, corrosion‐resistant metal. There are four commonly known polymorphs of TiO₂: anatase (tetragonal), brookite (orthorhombic), rutile (tetragonal), and TiO₂ (B) (monoclinic) [4]. Various polymorphs of TiO₂ differ from each other with respect to their respective bandgap energies, i.e. 3.2, 3.02, and 2.96 eV for the anatase, rutile, and brookite phases, respectively [5].

Synthesis of nanoparticles involves two general approaches, namely: (a) bottom‐up and (b) top‐down approach (Figure 8.1). Bottom‐up approach ...