Boosting hydrogen gas production and mitigation of fluorescein dye on the surface of S-scheme g-C3N4/SnO2 heterojunction

In this research work, a highly efficient step S-scheme g-C3N4/SnO2 heterojunctions containing various concentration of g-C3N4 0–20 wt.% are controllable designed through sonochemical process for generation of hydrogen gas and decomposition of anionic fluorescein dye into eco-friendly species. Spheroid mesoporous SnO2 nanoparticles were manipulated by controlled sol–gel process. In ultrasonic bath of intensity 150 W, a step S-scheme heterojunctions were constructed by mixing various proportions of g-C3N4 and SnO2 nanoparticles. The change in the physicochemical properties are recorded by high-resolution transmission electron microscopy, X-ray diffraction, N2 adsorption– desorption isotherm, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy and photoluminescence spectroscopy (PL). With introducing 10 wt.% g-C3N4, the removal of fluorescein dye reach 92% and hydrogen gas evolution rate is 6.56 mmol/g h which is tenfold higher than that of pristine SnO2. The shifting in XPS peaks of Sn4+ and reduction of PL intensity of the nanocomposite reveal the successful generation of g-C3N4/SnO2 heterojunction. The charge carriers transportation proceeds through step S-scheme mechanism that generate an internal electric fields at the interface boundary between the two semiconductors. The durability of this novel nanocomposite can be deduced from the achievement of 86% of photocatalyst reactivity after six consecutive cycles.