Triphenylphosphine ruthenium (RuP) complex anchored with exfoliated g-C₃N₄ (ECN) with an externally reflected solar photoreactor system for highly efficient solar H₂ production

Designing an efficient photocatalytic system capable of higher photocatalytic efficiency for hydrogen production is extremely challenging. In the current study, a triphenylphosphine ruthenium (RuP) complex as a cocatalyst with exfoliated g-C₃N₄ nanosheets (ECN) and an externally reflected solar photoreactor has been investigated for photocatalytic H₂ production. With the alternate morphology of g-C₃N₄, both the specific surface area and charge separation efficiency were enhanced. The ruthenium (RuP) complex attached to ECN (RuP/ECN) enables efficient visible light absorption due to works as a photosensitizer to yield more hydrogen. The 3% RuP/ECN exhibited excellent photocatalytic efficiency, and optimal H₂ yield reached up to 1705 µmol g⁻¹ with QY 2.85 %, 23.4 and 334 folds more than attained with pure ECN and bulk g-C₃N₄, respectively. Due to the exfoliated structure with photosensitization and oxygen vacancies, the photoactivity was greatly increased for visible light assisted H₂ evolution. Furthermore, using an externally reflected solar photoreactor system, H₂ yield was significantly improved due to concentrating more light irradiations inside the slurry system even at lower light intensity. Using the traditional and externally reflected solar systems, the critical operational parameters, including sacrificial reagents, feed concentration, and catalyst loading, were further explored. Mass transfer, charge transfer, and amount of photoinduced charges were greatly dependent on the operating parameters. The highest H₂ yield with lower catalyst loading and feed concentration was obtained with an externally reflected solar system. This study introduces a new technique to manufacturing porous materials and creating an effective photoreactor system that might be advantageous to boost performance in other solar energy-related applications.