Photocatalytic Performance of TiO2-Based Nanomaterials for Water Remediation

Photocatalytic water treatment using titanium dioxide (TiO2)-based nanomaterials has emerged as a promising green technology for removing organic and inorganic contaminants. However, the translation of laboratory-scale photocatalysts into industrial applications remains limited by material complexity, synthesis scalability, and process integration. This study presents a systematic review combining bibliometric and patent analyses to evaluate the evolution of TiO2-based photocatalysis for water remediation from 2006 to 2025. Following PRISMA 2020 guidelines, a Scopus search identified 1402 publications, from which 152 representative studies were selected for detailed qualitative analysis. Bibliometric mapping using VOSviewer revealed four major thematic clusters: hybrid materials for advanced photocatalysis; biopolymers and membrane-based water treatment; advanced TiO2 nanostructures; and advanced synthesis methods for TiO2 nanomaterials. Patent analysis of 80 representative patent families from the Orbit (Questel) database revealed a 375% increase in patent activity over the last decade, with China and India accounting for approximately 80% of global patent activity. Overall, the field has evolved from conventional TiO2 nanoparticles toward multifunctional architectures, including ternary composites, S-scheme heterojunctions, plasmonic systems, and defect-engineered photocatalysts. Nevertheless, conventional multistep synthesis routes, particularly sol–gel and hydrothermal methods, remain dominant, while scalable approaches such as flame spray pyrolysis (FSP) and ultrasonic spray pyrolysis (USP) are scarcely represented in both scientific and patent landscapes. These findings indicate that future progress will depend less on increasing material complexity and more on scalable, sustainable, and economically viable manufacturing strategies capable of enabling industrial water-treatment applications and accelerating reliable technology transfer, long-term stability, and validation in real wastewater treatment matrices.