Advanced TiO2 Based Photocatalytic Systems for Water Splitting: A Comprehensive Review from Fundamentals to Manufacturing

The global imperative for clean energy solutions has positioned photocatalytic water splitting as a promising pathway for sustainable hydrogen production. This review comprehensively analyzes recent advances in TiO2-based photocatalytic systems, focusing on materials engineering, water source effects, and scale-up strategies. We recognize the advancement in nanoscale architectural design, engineered heterojunction of the catalyst, and cocatalyst integration that have significantly enhanced photocatalytic efficiency. Particular emphasis is placed on the crucial role of water chemistry in photocatalytic system performance, analyzing how different water sources—from wastewater to seawater—impact hydrogen evolution rates and system stability. Additionally, the review addresses key challenges in scaling up these systems, including optimization of reactor design, light distribution, and mass transfer. Recent developments in artificial intelligence-driven materials discovery and process optimization are discussed, along with emerging opportunities in bio-hybrid systems and CO2 reduction coupling. Through critical analysis, we identify fundamental challenges and propose strategic research directions for advancing TiO2-based photocatalytic technology toward practical implementation. This work will provide a comprehensive framework for researchers to explore advanced TiO2-based composite materials to develop efficient and scalable photocatalytic systems for multifunctional simultaneous hydrogen production.