2D/2D confinement graphene-supported bimetallic Sulfides/g-C₃N₄ composites with abundant sulfur vacancies as highly active catalytic self-cleaning membranes for organic contaminants degradation

Recently, advanced oxidation processes (AOPs) combined with membrane filtration as highly active catalytic self-cleaning membrane to decrease energy and cost consumption has attracted considerable attention in environmental remediation. In this study, a kind of novel 2D bimetallic sulfides/N-doped reduced graphene oxide (FeCoS@N-rGO) composite was firstly developed via the self-assembly of MOFs and GO nanosheets followed by carbonization and further sulfuration, subsequently 2D/2D catalytic membrane (FeCoS@NGC) was fabricated by intercalating FeCoS@N-rGO into adjacent graphitic carbon nitride (g-CN). As expected, the synergistic interaction from N-rGO/FeCoS (confinement effect) and sulfur species (co-catalytic behavior) not only provided fast mass/electron transfer but also suppressed the aggregation and leaching of metal, of which FeCoS-4@N-rGO, attained 99.4% (0.254 min⁻¹ vs 0.025 min⁻¹ of FeCoS nanoparticles) sulfamethoxazole (SMX, 30 mg/L) degradation after 20 min via activating peroxymonosulfate (PMS). Remarkably, the permeation flux of FeCoS@NGC membrane was significantly enhanced (632.12 L m^-2h⁻¹ vs 76.45 L m^-2h⁻¹ of g-CN membrane). Significantly, the catalytic self-cleaning performance of composite membrane was investigated through the synergistic membrane filtration and degradation of methylene blue (MB). Furthermore, FeCoS@NGC was employed to efficient eliminate other pollutants, including tetracycline, bisphenol A, rhodamine B and perfluorooctanoic acid. Finally, sulfate radical (SO₄[rad]^-), superoxide radical (O₂[rad]^-) and singlet oxygen (¹O₂) were verified as dominant force responsible for SMX degradation. Consequently, this study provided new insight into constructing sulfur vacancies-rich 2D/2D confinement catalytic membrane with catalysis-driven flux recovery in wastewater purification.