Development of dual functional heterostructured g-C3N4/CdS nanocomposites for visible light photocatalytic dye degradation and electrochemical hydrogen production

Abstract

This study investigates the synthesis and dual functionality of heterostructured g-C₃N₄/CdS nanocomposites (NCs) for photocatalytic dye degradation and electrochemical hydrogen evolution. The g-C₃N₄/CdS NC was successfully synthesized utilizing a hydrothermal approach. The synthesized NCs were analyzed for their optical, structural, and morphological features using a variety of characterization techniques, such as UV vis DRS, XRD, XPS, TEM, and BET. The photocatalytic performance was evaluated through the decomposition of MB under solar light and visible light. Among the synthesized samples, the 40 wt% g-C₃N₄/CdS NC demonstrated the greatest activity, achieving ∼97% degradation of MB within 80 minutes under visible light irradiation. Such improved results stemmed from improved light absorption, increased specific surface area (99.06 m² g⁻¹), and diminished recombination of charge carriers. The reduced recombination behavior was further explained based on the band alignment of the heterostructure. Scavenger investigations indicated that conduction band electrons and superoxide radicals were the principal reactive oxidative species facilitating MB degradation. Moreover, electrochemical investigations (LSV, Tafel slope, EIS, and OCP) demonstrated that the heterojunction g-C₃N₄/CdS NCs markedly improved HER activity by enhancing the charge transfer kinetics and reducing the overpotential in comparison to pure CdS and g-C₃N₄. The GC electrode modified with 40 wt% g-C₃N₄/CdS NCs achieved a current density of 10 mA cm⁻² at an overpotential of only 191 mV, whereas the CdS and C₃N₄-modified electrodes required significantly higher overpotentials of 564 mV and 341 mV, respectively. Exceptional stability and reusability were exhibited by the nanocomposites, maintaining over 91% photocatalytic efficiency after three cycles. Overall, this research underscores the remarkable potential of g-C₃N₄/CdS NCs as efficient, stable, and multifunctional materials for environmental remediation and clean hydrogen production.