Sustainable scalable solid-state synthesis of highly efficient synergetic 2D/0D micro/nanostructured g-C3N4/CdS photocatalysts for hydrogen production and water purification

Abstract

Highly efficient synergetic photocatalysts based on graphitic carbon nitride (g-C3N4) and cadmium sulfide (CdS) semiconductors with 2D/0D micro/nanostructure were successfully prepared by easy scalable mechanochemical method and investigated. An in-depth study of electrons' binding energy of semiconductors and their influence on the photocatalytic activity of nanocomposites has been performed. The synthesized materials were applied for the photodegradation of Orange II dye and photocatalytic hydrogen evolution. The obtained experimental results revealed that nanocomposite with 20 wt% of g-C3N4 and 80 wt% of CdS is able to completely decompose Orange II molecules after two hours of visible light irradiation. The mechanism and pathways of photocatalytic reactions have been proposed. The nanocomposite composed of 60 wt% g-C3N4 and 40 wt% CdS, decorated by a platinum (Pt) co-catalyst, demonstrated the peak hydrogen evolution rate (HER) of 2254.54 μmolh−1 g−1 after 4th hour of solar light illumination. This remarkable achievement, with an apparent quantum efficiency (AQE) of 2.0%, occurred on the fourth hour of solar light irradiation. Furthermore, under continuous visible light irradiation, the sample with the same composition is capable of producing hydrogen. The peak HER rate recorded was 246.14 μmolh−1 g−1 (AQE = 0.44%) after 2.5 h, and this remained consistently the same throughout the entire duration of the process.