Advanced TiO₂-Based Photocatalytic Systems for Water Splitting: Comprehensive Review from Fundamentals to...

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 advancements in nanoscale architectural design, the engineered heterojunction of catalysts, and cocatalyst integration, which 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 the 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 the fundamental challenges and propose strategic research directions for advancing TiO₂-based photocatalytic technology toward practical implementation. This work will provide a comprehensive framework for exploring advanced TiO₂-based composite materials and developing efficient and scalable photocatalytic systems for multifunctional simultaneous hydrogen production.