Abstract

Per- and polyfluoroalkyl substances (PFAS), including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), are persistent environmental pollutants widely detected in water due to their extensive industrial and urban applications. Their bioaccumulative and toxic nature is associated with adverse health effects, including thyroid dysfunction, hepatotoxicity, immune suppression, and potential carcinogenicity, as well as ecological impacts such as microbial community disruption and the propagation of antibiotic resistance genes. Conventional PFAS removal methods, including adsorption, ion exchange, and membrane processes, are constrained by high costs, the generation of secondary waste, and limited efficiency for short-chain PFAS.
Photocatalysis, an advanced oxidation process, presents a sustainable approach for the complete defluorination and mineralization of PFAS under mild conditions. However, traditional photocatalysts such as TiO2 are restricted by their wide band gap and UV light dependence, prompting the exploration of alternative materials. While gallium oxide, indium oxide, and graphitic carbon nitride have been investigated, their photocatalytic performance remains constrained by limited solar absorption and rapid charge carrier recombination.
This study focuses on the synthesis, characterization, and enhanced photocatalytic degradation of Cu2S nanostructures for the removal of PFOA and PFOS in water. The materials, including CuS, Cu2S, a mixed-phase (Cu2S/CuS) Cu2S3/2, and Cu2S integrated with reduced graphene oxide (rGO), were synthesized via hydrothermal and solvothermal methods, thoroughly characterized, and tested under UV irradiation to assess their degradation efficiency and potential synergistic effects in composite systems. Among the prepared photocatalysts, Cu2S3/2 exhibited the highest degradation activity, achieving up to 99% PFOS removal and 93% PFOA degradation, while Cu2S showed comparable efficiency. In contrast, the Cu2S/rGO composite displayed moderate degradation efficiency of 76%.
These results highlight the potential of Cu-based nanostructures, whose tunable morphologies and favorable photoactive properties offer promising solutions to current limitations in PFAS treatment. The observed high degradation efficiencies, combined with the versatility of the synthesis methods, suggest that these Cu2S nanostructures can be further optimized for large-scale water remediation applications. Overall, this work demonstrates the enhanced photocatalytic performance of Cu2S nanostructures in water remediation, providing a comprehensive framework for the design of effective, scalable, and environmentally sustainable strategies to manage emerging contaminants such as PFAS. These findings not only advance the understanding of copper sulfide–based photocatalysts but also offer practical insights for addressing persistent water pollutants in real-world scenarios.
Keywords: Advanced catalysts, PFAS photocatalysis, Copper sulfide photocatalyst materials, PFAS degradation, Visible-light photocatalyst, Water treatment