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Copper-phenylacetylide (PhC2Cu) is a promising candidate for photocatalysis. Herein, an S-scheme heterojunction of PhC2Cu/Ag/Ag2MoO4(PAM) photocatalyst was synthesized for the effective and stable photocatalytic reduction of sulfamethazine (SMT) under blue LED light. In the optimal PAM40 system, the kinetic rate constant for the degradation of SMT was 0.1622 min−1, which was 16.3 times that of PhC2Cu (0.0099 min−1). The enhanced photocatalytic performance was attributed to efficient photoexcited charge separation, higher innergenerated-H2O2and greater oxidation–reduction capacities for the generation of reactive oxygen species (ROS). The potential photocatalytic mechanism of the S-scheme PAM40 was elucidated through relevant characterization and experimental investigations, which confirmed the existence of an internal electric field (IEF), which promoted photocarrier separation and transport. The SMT degradation pathways were proposed, and the developmental toxicities of the intermediates were predicted. Moreover, this work compounded the materials with innergenerated-H2O2capability (PhC2Cu) and with H2O2catalytic capability (Ag2MoO4), which provides an innovative perspective for the synthesis of S-scheme heterojunction photocatalysts with superior activities.

Since it has been found that tetracycline (TC) causes significant harm to ecosystems and human health, there has been an intense commitment toward its effective remediation in the ambient environment. For this study, a novel bismuth subcarbonate/bismuth oxide (Bi2O2CO3/Bi2O3) heterojunction photocatalyst containing oxygen vacancies (OVs) and bismuth (Bi-BOC/BO-OVs) was successfully synthesized using a simple calcination method. The defect state provided by the OVs increased light absorption and the population of adsorption sites, which played pivotal roles in the removal of TC. Therefore, within the catalyst dosage range of 0.4 g L−1, the reaction rate constant increased with greater TC adsorption. As a bridge for electron transport, bismuth (Bi) linked the valence band of Bi2O2CO3and the conduction band of Bi2O3to form a Z-scheme heterojunction structure, which promoted the effective separation of electron–hole pairs and the yield of active oxygen species. Consequently, the Bi-BOC/BO-OVs demonstrated a significantly enhanced photocatalytic degradation capacity for TC under visible light irradiation. The sufficient degradation of TC in simulated water matrices and different initial pH indicated that the Bi-BOC/BO-OV photocatalytic system possessed tremendous potential for the remediation of TC wastewater.

The development of facile and environmentally compatible synthetic strategies for broad-spectrum response photocatalysts is a primary goal for researchers in this area. For this study, we report on a template-free thermal treatment strategy for the synthesis of an oxygen-containing ultrathin porous carbon quantum dots/polymeric carbon nitride metal-free composites (CQD/OUPCN). Morphology characterization revealed that the thermal treatment induced bulk CQD/g-C3N4(CQD/BCN) to transform to porous ultrathin 2D nanosheets with a high specific surface area. Chemical structure characterization revealed that O atoms were involved in the chemical composition of C3N4following the introduction of CQD and subsequent thermal treatment. Optical and electrical characterization, as well as density functional theory (DFT) calculations, confirmed that the introduction of O atoms and CQD enabled the tuning of the intrinsic electronic state, and improved the charge transfer capacity of C3N4. Together with the up-converted fluorescence properties of CQD, the CQD/OUPCN exhibited remarkable broad-spectrum activity toward the degradation of PPCPs. Under visible light irradiation, the CQD/OUPCN-0.5% showed an 18.5 fold higher indomethacin (IDM) degradation rate than did g-C3N4. Further kinetics studies, including reactive species (RS) and degradation intermediate detection, indicated that RS, particularly O2−, was generated during the photocatalytic process, which could lead to the decomposition, and finally mineralization of IDM.