An investigation on g-C3N4/ZnS/SnO2 ternary nanocomposites for electrochemical alkaline water splitting and photocatalytic methylene blue decomposition reactions

Abstract

In this study, we report the development of a cost-effective and highly efficient bi-functional g-C₃N₄/ZnS/SnO₂ ternary nanocomposite for electrochemical hydrogen evolution reaction (HER) and photocatalytic applications under sunlight irradiation. The nanocomposites were synthesized using a facile hydrothermal method, combining semiconducting ZnS and SnO₂ nanomaterials with g-C₃N₄ nanosheets. Comprehensive characterization techniques were employed to analyze the structural, morphological, electrochemical, and photocatalytic properties of the synthesized nanocomposite. X-ray diffraction (XRD) analysis demonstrates that the g-C₃N₄, g-C₃N₄/ZnS, and g-C₃N₄/ZnS/SnO₂ nanostructures exhibit excellent crystallinity, as evidenced by the sharp and well-defined peaks in the XRD patterns. Field emission scanning electron microscopy (FESEM) reveals the deposition of spherical ZnS nanoparticles and agglomerated SnO₂ nanoparticles on g-C₃N₄ nanosheets, forming a ternary nanocomposite structure. The g-C₃N₄/ZnS/SnO₂ ternary nanocomposite exhibits a high Brunauer–Emmett–Teller (BET) surface area of 118.123 m² g⁻¹ and an optical band gap of 2.88 eV. Electrochemical measurements show that the nanocomposite has enhanced catalytic activity for the HER, with a low Tafel slope of 92 mV dec⁻¹ and an overpotential of − 0.372 V vs. RHE at 10 mA cm⁻². Furthermore, the g-C₃N₄/ZnS/SnO₂ ternary nanocomposite demonstrates excellent photocatalytic performance, exhibiting high degradation efficiency against methylene blue (MB) dye under sunlight exposure. The synergistic effects of the ternary nanocomposite structure, high surface area, and suitable optical properties contribute to the enhanced photocatalytic and electrocatalytic activities. The developed g-C₃N₄/ZnS/SnO₂ ternary nanocomposite shows great potential as a cost-effective and highly efficient bi-functional material for sustainable energy applications of hydrogen evaluation and environmental remediation.