Solar light-responsive α-Fe2O3/CdS/g-C3N4 ternary photocatalyst for photocatalytic hydrogen production and photodegradation of methylene blue

Photocatalytic degradation of waste materials in aqueous solutions, as well as photocatalytic hydrogen generation, were investigated for remediation of environment and renewable energy production. α-Fe2O3 and CdS are attractive visible-light-driven semiconductor photocatalysts because of their inexpensive cost, simple production methods, and stability. Whereas, its implementations were limited by the photocorrosion, narrow optical band gap for solar-light operations and poor separation of photogenerated electron-hole pair. To increase the performance of α-Fe2O3, CdS, α-Fe2O3/CdS, and g-C3N4; a ternary nanocomposite (α-Fe2O3/CdS/g-C3N4) was designed. To obtain binary structure, CdS nanoparticles were overgrown on α-Fe2O3 nanorods-cubes using a simple wet-chemical process, and as-prepared g-C3N4 was decorated with binary composite. XRD, SEM, XPS, BET, UV–Visible spectrometry, FT-IR, PL and EIS were employed to investigate the crystal structures, surface morphology, optical properties, functional groups and electrochemical characteristics. Considering the optical absorption properties, the photocatalytic studies were performed for hydrogen production and MB dye degradation under solar light irradiation. Among the synthesized semiconductors, the ternary material had the highest photocatalytic hydrogen evolution, 165 µmol g−12 h−1 from water. Within 120 min, the photocatalytic performance resulted in 99.4% degradation of the MB. The higher activities were attributed to Z-scheme mechanism, optical band levels and strict heterojunctions of the photocatalysts that induces an influential electron-hole separation, subsequently rapid diffusion of photogenerated charge between components and also the optical bandgap value of the ternary structure that more convenient for solar lights applications. This work paves a way for improvement of photocatalysts working in practical conditions of pollution and energy issues.