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In this paper, Eu/F co-doped bismuth vanadate photocatalysts with different doping ratios were prepared by a hydrothermal method, and their microscopic morphology, crystal structure, light absorption and photocatalytic performance were investigated. Part of the F in the Eu/F co-doped samples might be doped to replace O in the BiVO4 lattice, while Eu3+ ions replaced Bi3+ ions, which led to a difference in the morphology and internal structure. XRD and Raman spectroscopy characterization showed that the crystal structures of the samples were all monoclinic scheelite type, and contained a certain tetragonal scheelite type, and the crystallinity was good. The Eu/F co-doped samples exhibited better photoactivity under UV-Vis light. The recombination rate of the photogenerated carriers in the Eu/F co-doped samples was obviously reduced, but it showed a serious concentration dependence on the doping species. Under visible light irradiation, Eu/F co-doped samples (R = 0.75) had the best degradation effect on methylene blue (MB). In addition, the degradation mechanism of the photocatalyst was also explored. ˙O2− and h+ were the main active species affecting the degradation of MB by Eu/F–BiVO4. [ABSTRACT FROM AUTHOR]

The development of high-efficiency photocatalytic materials responsive to visible light is one of the most effective ways to address the environmental threats posed by organic dyes in industrial wastewater. In this paper, novel visible-light-responsive nitrogen–sulfur co-doped carbon quantum dots modified ZnO (ZnO/N,S-CQDs) composites with a significantly enhanced photocatalytic degradation performance of Rhodamine B (RhB) were successfully synthesized. Under visible light, the photocatalytic degradation efficiency reached 98.7% over the optimal composite. Besides, the degradation obeyed the pseudo-first-order kinetics model with a photocatalytic rate constant (k) of 0.0473 min−1, which was around 3.71 times higher than that of pure ZnO nanoparticles (0.01273 min−1). In addition, the morphology, size and elemental composition of the ZnO/N,S-CQDs were characterized using TEM, SEM, XRD, FT-IR, and XPS which confirmed the successful synthesis of the composites. Photoluminescence (PL) and transient photocurrent response results indicated an increase in the carrier separation efficiency of ZnO/N,S-CQDs. Based on the active species removal experiment, superoxide radicals (˙O2−) played a leading role in the photocatalytic reactions and a possible photocatalytic degradation mechanism was revealed. These further demonstrate that the N,S-CQDs with varying properties contributed significantly to the enhanced photocatalytic activity of ZnO. Overall, the present method follows the principle of green economy, and novel N,S-CQDs provide a feasible approach for the development of photocatalytic performance of ZnO. [ABSTRACT FROM AUTHOR]

The presence of antibiotics in aquatic systems poses a significant risk to both the ecological balance and human health. To address this issue, the development of advanced photocatalytic materials capable of efficiently treating antibiotic-contaminated wastewater is imperative. In this investigation, we successfully synthesized nitrogen–phosphorus co-doped carbon dots (NPCDs) modified (001) TiO2/Ti3C2Tx composites via a series of uncomplicated hydrothermal reactions, ensuring visible light responsivity. Comprehensive characterization of the composite photocatalysts was conducted using XRD, FT-IR, N2 adsorption, SEM, TEM, XPS, UV-Vis DRS, and PL techniques. Subsequently, the photocatalytic performance was assessed through the degradation of tetracycline hydrochloride (TC) and ceftiofur sodium solutions under visible light irradiation. The optimized composites exhibited remarkable photocatalytic degradation efficiencies of 93.4% and 75.5% for TC and ceftiofur sodium, respectively, under visible light, following quasi-primary kinetic behavior. Reactive free radical capture experiments highlighted the predominant roles of ˙O2− and ˙OH species in the photocatalytic degradation process. Additionally, we proposed plausible mechanisms governing photocatalytic degradation based on the obtained results. The heightened photocatalytic reactivity arises from the efficient transfer of photogenerated electrons through the NPCDs → TiO2 →Ti3C2Tx pathway, a mechanism that effectively facilitates the separation and transfer of photogenerated charge carriers. [ABSTRACT FROM AUTHOR]

Molecularly imprinted Ni and F co-doped TiO2 nanoparticles were synthesized via the sol–gel method. The nanoparticles displayed high photocatalytic activity under both sunlight and artificial visible light for degradation of bisoprolol. Characterization of the nanoparticles was carried out using XRD, FE-SEM, TEM, FT-IR, DRS, EDX and BET-BJH. The effects of different operational variables on the photocatalytic activity were optimized using the response surface methodology (RSM). The optimal experimental conditions for achieving the highest photocatalytic efficiency (72.5% by a desirability function value of 1.0) are as follows: pH = 5.9, photocatalyst mass = 83.42 mg, bisoprolol concentration = 16.2 mg L−1, and irradiation time = 137 min. The selectivity of the photocatalyst was investigated against pantoprazole. The excellent photocatalytic activity is attributed to the doping of Ni and F dopants into the TiO2 structure. The investigation of the mechanism of the photocatalytic reaction revealed that the main active species involved in the degradation of bisoprolol are OH˙ radicals. [ABSTRACT FROM AUTHOR]

Element doping is an effective approach to modify the electronic structure of semiconductors and improve the photocatalytic activity. Herein, we designed a process for the oxygen doping of lamellar ZnIn2S4 (O-doped ZIS) nanosheets that were coated on layered g-C3N4 (CN) to form a g-C3N4/O-doped ZnIn2S4 (CN/O-doped ZIS) heterojunction to improve the charge separation efficiency, thereby boosting the photocatalytic performance of CN/O-doped ZIS. The optimized 20% CN/O-doped ZIS showed high photocatalytic performance (RhB, 97% in 20 min) under visible light, which is 19.6 and 2.5 times higher than that of CN and O-doped ZIS photocatalysts, respectively. In the investigations on the band structure, trapping experiments, and ESR tests, the photocatalytic mechanism of RhB degradation by the CN/O-doped ZIS composite was proposed. The photocatalytic performance was effectively promoted via oxygen doping and coupling with CN, which opens new insight into a highly efficient photocatalytic system. [ABSTRACT FROM AUTHOR]

A multifunctional α-MnO2/ZnO--C (MZ) Z-scheme photocatalyst was synthesized by the suit-growth of α-MnO2 on the surface of MOF-5 and pyrolysis of the organic components under certain conditions. The obtained photocatalysts were characterized and the photocatalytic activity was investigated by degrading tetracycline (TC). Especially, the composite with a 15% mass ratio of α-MnO2 (15-MZ) exhibited the best photocatalytic activity for tetracycline under visible light irradiation and the degradation efficiency for TC reached 96.69% within 60 min. The doping of the C element in the ZnO crystal structure formed an intermediate energy level to narrow the band gap of ZnO, which was beneficial for visible light absorption. Also, the construction of a binary synergistic system between ZnO and α-MnO2 resulted in the extension of the light response range and accelerated the transfer of photogenerated carriers. The tests showed that h+, ¹O2, •O2-, and •OH were the main active species and played leading roles in the degradation process. Additionally, the residual C species as an electron-transfer medium were conducive to constructing the Z-scheme heterojunction between ZnO--C and α-MnO2, which provides an interesting approach for designing visible light responsive photocatalysts. [ABSTRACT FROM AUTHOR]