Titanium dioxide (TiO₂) has received a lot of attention due to its inexpensive cost, benign nature, and great photocatalytic potential. TiO₂ has numerous applications, including in photocatalysts, Li-ion batteries, solar cells, and medical research. However, its performance is unsatisfactory due to a variety of issues, including a wide band gap (3.01 to 3.2 eV) and quick electron-hole pair recombination (1012 to 1011 s). Many efforts have been made to improve the qualities of TiO₂, such as structural and dopant changes, which expand its applications. This book focuses on the properties of TiO₂-modified nanoparticles, including their synthesis, alterations, and applications.