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CeO 2 nanoparticles are successfully loaded on carbonate doped Bi 2 O 2 CO 3 (CBOC) nanosheets by a facile hydrothermal and low-temperature calcination method. CeO 2 /CBOC heterojunction shows significantly enhanced photocatalytic activity, when 35 mg of CeO 2 /CBOC photocatalyst is added to tetracycline (TC) solution (20 mg/L, 100 mL), about 79.5% TC is degraded within 90 min under visible light irradiation, which is much higher than that of original CeO 2 and CBOC. According to photoelectrochemical characterization and active radical capture experiments, the Z-scheme electron transfer mechanism is the reason for the significant enhancement of photocatalytic activity. Besides, the XPS results indicate that Ce4+/Ce3+ redox pairs are formed at the contact interface between CeO 2 and CBOC, which is conducive to the transfer of photoexcited electrons and production of superoxide radicals. Additionally, the photocatalytic mechanism and possible degradation pathway of TC is proposed through free radical trapping experiments and liquid chromatography-mass (LC-MS) analysis. This study will accumulate experience for the combination of CeO 2 and bismuth-based nanomaterials, and provide a feasible way to design wide band-gap bismuth-based photocatalysts, thereby achieving efficient visible light degradation of environmental pollutants. [ABSTRACT FROM AUTHOR]

• A novel benzene ring modified g-C 3 N 4 photocatalyst is successfully synthesized. • BCNNS exhibits excellent light response and the separation of charge carriers. • The modification of benzene ring can promote the activation of molecular oxygen. • BCCNS shows improved photocatalytic activity for OTC degradation. Popular graphitic carbon nitride (g-C 3 N 4) photocatalyst always faces the problems of weak visible light absorption and fast recombination of photogenerated electron-hole pairs. Herein, a novel benzene ring modified g-C 3 N 4 nanosheet (BCNNS) was synthesized by a simple calcination method. The degradation rate of oxytetracycline by BCNNS under visible light can reach 72% (within 60 min), significantly higher than that of the unmodified g-C 3 N 4 nanosheet (50%). And the degradation rate constant of BCNNS is 0.025 min−1, which is 2.1 times higher than that of g-C 3 N 4 (0.012 min−1). The improvement in the photocatalytic degradation performance can be attributed to the introduction of benzene ring, which can significantly broaden the light absorption range and intensify. In addition, the introduction of benzene ring can adjust the original electronic structure, thereby effectively suppressing the recombination of electron-hole pairs. Furthermore, density functional theory (DFT) calculations demonstrate that the introduction of benzene ring can significantly promote the surface adsorption of molecular oxygen and promote the transfer of electrons to molecular oxygen. This demonstrates that the embedded benzene ring can effectually advance the activation of molecular oxygen, which also well confirms that O 2 − and 1O 2 are the main active species in the system of BCNNS photocatalytic degradation of oxytetracycline. This study reveals that benzene ring modified g-C 3 N 4 has great potential in environmental purification, and provides a promising strategy for the removal of stubborn water contaminants. [ABSTRACT FROM AUTHOR]

The increasingly serious pollution of antibiotics brings an enormous threat to the ecological environment and human health. Graphite phase carbon nitride (g-C 3 N 4), as a popular photocatalytic material, is widely used in photocatalytic degradation of antibiotics in water. In order to make up for the shortage of g-C 3 N 4 monomer, CeO 2 /N-doped g-C 3 N 4 (CeNCN) composite photocatalysts co-modified with nitrogen doping and CeO 2 loading were designed and synthesized with the idea of expanding visible light absorption and promoting photogenerated carrier separation. CeNCN exhibits excellent photodegradation performance, the removal rate of tetracycline reached 80.09% within 60 min, which is much higher than that of g-C 3 N 4 (CN) and N-doped g-C 3 N 4 (NCN); and the quasi-first-order degradation rate constant is 0.0291, which is 7.86 and 2.29 times higher than CN and NCN. Electron spin resonance and free radical trapping experiments confirmed that h+, O 2 − and OH are the active substances in the photocatalytic system. After 5 cycles, the degradation efficiency of tetracycline still exceeds 75%, which indicates that CeNCN has good stability. This work proves that N-doping and CeO 2 loading can effectively broaden the photoresponse range of g-C 3 N 4 , facilitate the separation of photogenerated electron-hole pairs, and provide a reference for the construction of g–C 3 N 4 –based photocatalyst with high-efficiency photodegradation activity. [Display omitted] • CeO 2 /N-doped g-C 3 N 4 (CeNCN) photocatalyst was successfully first synthesized. • CeNCN exhibits excellent light response and the separation of charge carriers. • CeNCN exhibits significantly enhanced photocatalytic activity for TC degradation. • The proposed photocatalytic mechanism toward CeNCN photocatalyst is illustrated. [ABSTRACT FROM AUTHOR]

At present, environmental pollution caused by refractory organic pollutants becomes more serious. Semiconductor-based photocatalysis technology, an idea and continuable technology by solar-light-driven, is widely employed to address this situation. Here, oxygen-vacancy rich WO 3 decorated monolayer Bi 2 WO 6 nanosheet composite as an atomic scale heterojunction with high active species and ultrafast charge carrier transfer was rationally constructed. The atomic scale V o -WO 3 /Bi 2 WO 6 composite displayed remarkable photoactivity comparing with pristine V o -WO 3 and Bi 2 WO 6 ultrathin nanosheet, and about 79.5% of Ciprofloxacin can be degraded within 120 min under visible light irradiation when 40 mg of photocatalyst was added into CIP solution (10 mg/L). The promoted photoactivity can be ascribed to the following points: (1) the composite possesses enormous surface pit, thereby expanding the species surface area and exposing more active site to promote antibiotic absorption; (2) the presence of abundant oxygen vacancy can facilitate the formation of more electrons, which can be consumed by adsorbed molecular oxygen to produce superoxide radical, thereby accelerating degradation organic pollutant; (3) ultrathin V o -WO 3 nanosheet decorated monolayer Bi 2 WO 6 can shorten the charge carrier transfer distance and enlarge interface contact area, then ensuring remarkable photodegradation efficiency. The reasons for promoted photodegradation efficiency were elaborated based on experiments results and ESR analysis and the degradation pathways of CIP were recorded via [(LC-MS)/MS]. After 5 run for the degradation of CIP, V o -WO 3 /Bi 2 WO 6 composite also exhibited great photodegradation efficiency, thereby demonstrating its excellent stability and reusability. [ABSTRACT FROM AUTHOR]

• FeOOH QDs/CQDs/g-C 3 N 4 0D/2D heterojunction has been first prepared. • 0D/2D heterojunction can realize H 2 O 2 generation and in-situ decomposition. • The composite has excellent charge carrier transfer and separation efficiency. • The introduction of CQDs can improve the photoconversion efficiency. • The generated Fe2+ in FeOOH QDs can promote H 2 O 2 in-situ decomposition. Hydrogen peroxide (H 2 O 2) was generally considered as an ideal energy carrier and environment-friendly oxidant to process environmental modification. Here, FeOOH QDs and CQDs was interspersed on g-C 3 N 4 ultrathin nanosheet to promote H 2 O 2 generation and in-situ decomposition. FeOOH QDs/CQDs/g-C 3 N 4 composite (FCCN) exhibited excellent photoactivity for degrading oxytetracycline (OTC) under visible light illumination. The accelerated photoactivity is ascribed to the following merits: 1) the exciton dissociation interface and carrier transfer channel are fabricated to facilitate photoexcited electron transfer; 2) the photoexcited electron can be rapidly utilized by molecular oxygen to generate H 2 O 2 , resulting in facilitated molecular oxygen activation; 3) Fe3+ in FeOOH QDs is reduced to Fe2+ by photoexcited electron, and then reacts with generated H 2 O 2 to produce OH, thereby promoting photodegradation efficiency. The H 2 O 2 generation yield of FCCN-2 composite was 224.24 µmol h−1 g−1, which was higher than that of pure g-C 3 N 4. 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation and O 2 − quantitative determination displayed outstanding molecular oxygen activation capacity of hybrid composite. Moreover, 0D/2D heterojunction photocatalyst displayed weakened charge carrier recombination efficiency (0.0015 s−1) and expedited surface carrier transfer efficiency (41.01%) compared to g-C 3 N 4 and CQDs/g-C 3 N 4 photocatalyst. Finally, the photodegradation mechanism were rationally evaluated based on the experiment results. [ABSTRACT FROM AUTHOR]