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[Display omitted] Increasing water pollution has imposed great threats to public health, and made efficient monitoring and remediation technologies critical to a clean environment. In this study, a versatile heterojunction of Au nanoparticles modified phosphorus doped carbon nitride (Au/P-CN) is designed and fabricated. The Au/P-CN heterostructure demonstrates improved light absorption, rapid separation of charge carriers, and improved electrical conductivity. Taking the toxic 4-chlorophenol (4-CP) as an example, an ultrasensitive photoelectrochemical (PEC) sensor is successfully demonstrated, exhibiting a wide linear range (0.1–52.1 μM), low detection limit (∼0.02 μM), significant stability and selectivity, as well as reliable analysis in real samples. Moreover, efficient photocatalytic degradation with a high removing efficiency (∼87%) toward 4-CP is also achieved, outperforming its counterpart of Au nanoparticles (NPs) modified graphitic carbon nitride (Au/g−CN, ∼59%). This work paves a new way for efficient and simultaneous detection and remediation of organic pollutants over versatile photoactive catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel g-C 3 N 4 /Fe 2 O 3 /rGO ternary composite was synthesised using a hydrothermal process. • The catalyst exhibits a high photocatalytic oxidation efficiency for the removal of sulfamethoxazole. • Reactive oxygen species were identified by quenching tests and electron paramagnetic resonance spectra. • Detailed mechanistic studies were performed to deduce the radical and non-radical degradation pathways. Rational design of semiconductor photocatalysts is an effective way to achieve efficient visible-light-driven environmental remediation. Herein, a series of graphitic carbon nitride (g-C 3 N 4) engineered hematite (Fe 2 O 3)/reduced graphene oxide (rGO) photocatalysts were synthesised and employed in visible-light-driven photo-Fenton-like degradation of sulfamethoxazole (SMX). The exceptional performance of the optimal photocatalyst (0.4-FerGCN-3) was achieved because of the successful structural integration of g-C 3 N 4 /Fe 2 O 3 /rGO for efficient separation and migration of photoinduced charge carriers (e−/h+). Photochemical decomposition efficiency was also optimised by analysing the important reaction parameters such as initial catalyst loading, initial H 2 O 2 dosage, pH, and reaction temperature. Detailed studies on the generation of reactive species and degradation intermediates were performed to propose a possible mechanism for SMX degradation. The findings may provide not only a strategy for nanostructure engineering of semiconductor photocatalysts but also insights into the effective remediation of emerging contaminants such as SMX. [ABSTRACT FROM AUTHOR]

Over the past few years, advanced oxidation processes (AOPs) have shown promising efficiencies for wastewater remediation. Carbocatalysis, in particular, has been exploited widely thanks to its sustainable and economical properties but has an issue of recovery and reusability of the catalysts. To address this, three-dimensional (3D) binary and ternary graphene-based composites in the form of macro discs were created to activate peroxymonosulfate (PMS) for catalytic oxidation of sulfamethoxazole (SMX). Graphene oxide served as the base, while graphitic carbon nitride (g-C 3 N 4) and/or single-walled carbon nanotubes (SWCNTs) were added. Among the various discs synthesized, rGNTCN discs (ternary composite) were proven to be the most efficient by completely degrading SMX in 60 min owing to their large surface area and nitrogen loading. The catalytic system was further optimized by varying the reaction parameters, and selective radical quenching and electron paramagnetic resonance tests were performed to identify the active radical, revealing the synergistic role of both radical and non-radical pathways. This led to the development of possible SMX degradation pathways. This research not only provides insights into ternary carbocatalysis but also gives a novel breakthrough in catalyst recovery and reusability by transforming nanocatalysts into macro catalysts. [Display omitted] • Novel graphene-based binary and ternary macro discs were fabricated. • The discs can activate peroxymonosulfate (PMS) for catalytic oxidation. • The identification of dominant reactive species was conducted. • PMS activation and sulfamethoxazole degradation pathways were illustrated. [ABSTRACT FROM AUTHOR]