Nanoscale engineering of semiconductor photocatalysts boosting charge separation for solar-driven H₂ production: Recent advances and future perspective

Photocatalytic hydrogen (H₂) production is regarded as an efficient method for generating renewable energy. Despite recent advancements in photocatalytic water splitting, the solar-to-hydrogen conversion efficiency of photocatalysts remains well below the 10% target needed for commercial viability due to ongoing scientific challenges. This review comprehensively analyzes recent advancements in nanoscale engineering of photocatalytic materials, emphasizing techniques to enhance photogenerated charge separation for efficient solar hydrogen production. Here we highlight the nanoscale engineering strategies for effective charge separation including crystal engineering, junction engineering, doping-induced charge separation, tailoring optoelectronic properties, hierarchical architecture, defects engineering, various types of heterojunctions, and polarity-induced charge separation, and discuss their unique properties including ferroelectric on spatial charge separation along with the fundamental principles of light-induced charge separation/transfer mechanisms, and the techniques for investigation. This study, critically assesses strategies for effective photogenerated charge separation to enhance photocatalytic hydrogen production and offers guidance for future research to design efficient energy materials for solar energy conversion.