This review discusses the development and application of TiO₂-based catalysts with various structures for photocatalytic processes. TiO₂ is a promising material due to its cost-effectiveness, high stability, and environmental friendliness, and it is used in applications such as hydrogen production and pollutant degradation. However, challenges such as a large band gap and rapid electron-hole recombination limit its practical use. Recent advances in materials science have led to strategies that enhance photocatalytic activity, including improved visible light absorption, stability, and charge carrier separation. The review covers different structural engineering methods, including 0D, 1D, 2D, and 3D TiO₂-based materials, and discusses recent synthesis methods and applications in various fields. It aims to provide a comprehensive overview to guide the development of new TiO₂-based catalysts for enhanced solar energy conversion. The review highlights the importance of structural design in improving photocatalytic performance. Anatase is considered the most effective TiO₂ polymorph for photocatalytic applications due to its higher conduction band edge, lower electron-hole recombination rate, and larger surface area. Rutile and brookite are also discussed, with their respective advantages and limitations. The review also explores heterojunctions, such as type-II and Z-scheme structures, which enhance charge separation and photocatalytic efficiency. Various synthesis methods, including hydrothermal, sol-gel, vapor deposition, and electrospinning, are described for producing different TiO₂ structures. The review emphasizes the role of surface area, crystallinity, and morphology in optimizing photocatalytic performance. It also discusses the application of TiO₂-based catalysts in environmental and energy-related processes, such as the degradation of pollutants and hydrogen production. The review concludes that the combination of structural design and functional optimization is crucial for developing efficient TiO₂-based photocatalysts.This review discusses the development and application of TiO₂-based catalysts with various structures for photocatalytic processes. TiO₂ is a promising material due to its cost-effectiveness, high stability, and environmental friendliness, and it is used in applications such as hydrogen production and pollutant degradation. However, challenges such as a large band gap and rapid electron-hole recombination limit its practical use. Recent advances in materials science have led to strategies that enhance photocatalytic activity, including improved visible light absorption, stability, and charge carrier separation. The review covers different structural engineering methods, including 0D, 1D, 2D, and 3D TiO₂-based materials, and discusses recent synthesis methods and applications in various fields. It aims to provide a comprehensive overview to guide the development of new TiO₂-based catalysts for enhanced solar energy conversion. The review highlights the importance of structural design in improving photocatalytic performance. Anatase is considered the most effective TiO₂ polymorph for photocatalytic applications due to its higher conduction band edge, lower electron-hole recombination rate, and larger surface area. Rutile and brookite are also discussed, with their respective advantages and limitations. The review also explores heterojunctions, such as type-II and Z-scheme structures, which enhance charge separation and photocatalytic efficiency. Various synthesis methods, including hydrothermal, sol-gel, vapor deposition, and electrospinning, are described for producing different TiO₂ structures. The review emphasizes the role of surface area, crystallinity, and morphology in optimizing photocatalytic performance. It also discusses the application of TiO₂-based catalysts in environmental and energy-related processes, such as the degradation of pollutants and hydrogen production. The review concludes that the combination of structural design and functional optimization is crucial for developing efficient TiO₂-based photocatalysts.