The article reviews the recent advancements in TiO₂-based catalysts with various structural heterostructures (0D, 1D, 2D, and 3D) for photocatalytic applications. These catalysts are widely studied due to their cost-effectiveness, high stability, and environmental friendliness, but they face challenges such as large band gaps and rapid electron-hole recombination. The review discusses recent structural engineering strategies that enhance photocatalytic activity, including improved visible light absorption, stability, charge-carrier separation, and specific surface area. It covers the synthesis methods and applications of TiO₂-based catalysts in various fields, aiming to provide a comprehensive guide for developing new generations of TiO₂-based catalysts. The article also delves into the photocatalytic mechanisms, including charge carrier separation and redox reactions, and the role of different polymorphs of TiO₂, such as anatase and rutile. Additionally, it explores the impact of particle size, crystallinity, surface-to-volume ratio, and surface chemistry on photocatalytic performance. The review highlights the advantages and disadvantages of various preparation methods, such as hydrothermal, sol-gel, vapor deposition, and electrospinning, and provides detailed examples of their applications in photocatalytic degradation of pollutants.The article reviews the recent advancements in TiO₂-based catalysts with various structural heterostructures (0D, 1D, 2D, and 3D) for photocatalytic applications. These catalysts are widely studied due to their cost-effectiveness, high stability, and environmental friendliness, but they face challenges such as large band gaps and rapid electron-hole recombination. The review discusses recent structural engineering strategies that enhance photocatalytic activity, including improved visible light absorption, stability, charge-carrier separation, and specific surface area. It covers the synthesis methods and applications of TiO₂-based catalysts in various fields, aiming to provide a comprehensive guide for developing new generations of TiO₂-based catalysts. The article also delves into the photocatalytic mechanisms, including charge carrier separation and redox reactions, and the role of different polymorphs of TiO₂, such as anatase and rutile. Additionally, it explores the impact of particle size, crystallinity, surface-to-volume ratio, and surface chemistry on photocatalytic performance. The review highlights the advantages and disadvantages of various preparation methods, such as hydrothermal, sol-gel, vapor deposition, and electrospinning, and provides detailed examples of their applications in photocatalytic degradation of pollutants.