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

Abstract

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.