Degradation Rate Of Tetracycline Hydrochloride Research Articles

Mechanism insight into boosting photocatalytic purification of tetracycline hydrochloride over 2D/2D S-scheme (BiO)2CO3/BiOCl heterojunctions

The (BiO)2CO3/BiOCl heterojunction holds promise for photocatalytic purification of antibiotics, which is primarily attributed to the type-II and Z-scheme photocharge separation mechanisms. However, it lacks a report on S-scheme heterojunction for efficiently promoting photocharge separation and retaining powerful redox capability. In this study, a 2D/2D S-scheme (BiO)2CO3/BiOCl (denoted as (BC/BL)1) heterojunction was prepared through the hydrothermal synthesis method. The as-synthesized (BC/BL)1 exhibited a significantly enhanced photocatalytic activity, with a degradation rate of tetracycline hydrochloride (TC-HCl) reaching 95.3% after 60minutes. Its kinetic constant of photodegradation surpassed that of (BiO)2CO3 and BiOCl by 20.8 and 3.8 times, respectively. A series of characterizations revealed that the improved photocatalytic activity of the (BC/BL)1 sample stemmed from the formation of a built-in electric field at the intimate interface, which strongly drove the photogenerated carriers to achieve the S-scheme separation. This study highlights the potential application prospects of photocatalyst (BC/BL)1 in antibiotic degradation.

Revealing the lattice engineering of Delafossite in core–shell CuRhO2@CuGaO2 heterostructure for efficient visible light photocatalytic activity

The establishment of heterojunctions at phase interfaces represents a pivotal strategy for enhancing photocatalytic performance. However, the inferior interfacial contact caused by the mismatch of crystal structure or lattice parameters seriously hampers the rapid and smooth migration of charge carriers in traditional heterojunctions. In this work, a tightly integrated Delafossite-based core–shell CuRhO2@CuGaO2 heterojunction was judiciously designed and constructed via a hydrothermal approach. Experimental and density-functional theory calculation results co-unravel that the built-in electric field is established in the lattice-matched heterogeneous interfaces, thereby providing smooth interface charge separation and transfer via the Z-scheme pathways. Benefitting from the heterojunction effect and unique core–shell coupling architecture, the strong visible light absorption and fast spatial charge transfer are realized in the CuRhO2@CuGaO2 heterostructure. The photocurrent density of the CuRhO2@CuGaO2 heterojunction is nearly 1.25 and 3.75 times those of pristine CuRhO2 and CuGaO2, respectively. As a result, the CuRhO2@CuGaO2 heterostructure reveals an excellent photocatalytic degradation rate of tetracycline hydrochloride, achieving a 3.02 and 2.38-fold improvement than those of the CuRhO2 and CuGaO2, respectively. This work is expected to pave the way for novel insights into the design of efficient heterojunction photocatalysts to steer the rapid photocarrier flows across the heterointerface.

Solvothermal synthesis of bismuth-based halide perovskites: Investigating the influence of alcohol solvents on photocatalytic performance

Our study explores the effect of different solvents on the synthesis of bismuth-based halide perovskite (BHP) crystals with distinct morphologies. BHP crystals were successfully synthesized using various alcohol solvents, including ethanol (EtOH), butanol (BuOH), ethylene glycol (EG), glycerol (GL), and without the use of alcohol solvents. The choice of solvent acted a crucial role in shaping the nucleation and growth of BHP crystals, as it affected key solvent characteristics, including dielectric constant, ion-coordination, and atomic chain length. The resulting BHP crystals exhibited varying geometrical and structural features, which, in turn, significantly impacted their photophysical properties and photocatalytic activity for the degradation of organic pollutants under visible light irradiation. The introduction of EtOH into the synthesis process led to larger crystallite sizes and an increased adsorption of oxygen molecules on BHP, thereby enhancing the separation of photo-excited electrons and holes. Consequently, the photodegradation efficiency of rhodamine B achieved an impressive 99.6% after 30 min of irradiation. The degradation rate of tetracycline hydrochloride over BHP photocalysts followed this order: mesoporous structure with strong agglomeration of particles (EtOH) > irregular agglomerates composed of spherical particles (BuOH) > irregular clusters of sheets (EG) > thick plates (GL) > flower-like agglomerates (without the use of an alcohol solvent). Our evaluation considered changes in morphological characteristics, surface properties, and photon absorption capacities of the BHP crystalline structures. This study provides valuable insights into the role of various alcohol solvents in tailoring the structure and improving the photocatalytic performance of BHP photocatalyst synthesized through the solvothermal route.

Synthesis of three-dimensional porous ZIF-67/Bi2S3 heterojunctions with improved photocatalytic activity under visible-light irradiation

Firstly, Bi2S3 material was prepared by hydrothermal synthesis method, and the ZIF-67/Bi2S3 composite photocatalyst material was obtained by adding different contents of Bi2S3 in the synthesis process of ZIF-67. Three-dimensional porous ZIF-67/Bi2S3 heterojunction has a high specific surface area and provides a large number of reaction sites, which can be fully in contact with organic molecules, thereby improving light capture and photocatalytic reaction activity. The Bi2S3 semiconductor has a bandgap of about 1.3 eV and has strong light absorption in the visible region. ZIF-67 has a band gap of about 1.98 eV, which is not only porous but also has a good band structure. The combination of Bi2S3 and ZIF-67 can not only expand the spectral absorption range, but also ZIF-67 can be used as Bi2S3 carrier, which is conducive to photogenic carrier separation, solving the problem of Bi2S3 easy aggregation, and improving the processing efficiency. The morphology and elemental composition of ZIF-67/Bi2S3 were studied by XRD, SEM and XPS, and the synthesis of ZIF-67/Bi2S3 was successful. The absorption capacity of visible light was studied by UV–Vis DRS, and it was confirmed that ZIF-67/Bi2S3 composite photocatalytic material has extensive absorption of light. The results show that the prepared ZIF-67/Bi2S3-40 % heterojunction has good photocatalytic performance. Under visible light irradiation, the degradation rate of tetracycline hydrochloride (TCH) by ZIF-67/ Bi2S3-40 % was 91.1 % within 90 min, which was 1.25 times and 4.6 times of the absorption efficiency of naked ZIF-67 and Bi2S3, respectively (72.4 % for ZIF-67 and 19.8 % for Bi2S3). Then the valence band and conduction band values of semiconductor materials were calculated by M−S curve, and finally the degradation mechanism of ZIF-67/Bi2S3 composite photocatalyst was deduced.

Efficient removal of tetracycline hydrochloride by high entropy oxides in visible photo-Fenton catalytic process

ABSTRACT A novel type of oxide material, high entropy oxide (Mn0.2Fe0.2Co0.2Ni0.2Cu0.2)3O4 (MFO) composites with spinel structure were successfully synthesized by a simple solution combustion in this paper, and it was first applied to the degradation of antibiotic organic pollutants in water by photo-Fenton. SEM and BET characterization showed that the composite was porous and had a large specific surface area. XPS results showed that Fe, Mn, Cu, Co and Ni all participated in the redox reaction of the catalytic process. The redox pairs of Mn2+/Mn3+, Cu+/Cu2+, Co2+/Co3+, Ni2+/Ni3+ can accelerate the Fe2+/Fe3+ redox cycling in MFO to activate H2O2 and produce more reactive oxygen species. The catalytic performance of MFO composite was investigated using tetracycline hydrochloride (TC-HCl) as a model pollutant. The results displayed that the degradation rate of TC-HCl by MFO was 92.9% when the initial pH was 4, the dose of H2O2 was 50 mM, and the irradiation time was 60 min. The high entropy oxide MFO composites could build up an internal electric field, which restrains electron–hole recombination, improves the transfer of photogenerated charge carriers and maximize photocatalytic property. In addition, the free radical capture experiment determined that the main active species of the degradation reaction were e−, •O2 − and •OH. The synergistic effect of the five components in the high entropy oxide strengthens lattice distortion and defects, increases oxygen vacancies, and thus has enhanced catalytic effect for TC-HCl degradation. This work shows that high entropy oxides have excellent catalytic performance for tetracycline organic pollutants, and it is speculated that high entropy oxides have good application prospects in the field of advanced oxidation technology for the degradation of organic pollutants.

Preparation of g-C3N4/{001}-AR-TiO2 composite photocatalyst and its degradation of tetracycline hydrochloride in sunlight

In this study, a {001}-AR-TiO2 catalyst (001-ART) was prepared by the sol–gel method, where g-C3N4 (CN) was combined with 001-ART to form g-C3N4{001}-AR-TiO2 (CN/001-ART). The crystal shape, morphology, optical properties, photoelectron-hole recombination, and specific surface area of the prepared materials were studied. Tetracycline hydrochloride (TTCH) was used as the target pollutant to investigate the catalytic properties, and the results showed that the specific surface area, visible light response range, band gap, photo-generated carrier separation ability, and average life span of 001-ART after CN composite integration increased. Furthermore, the degradation rate of TTCH within 120 min was 92.48%, and the reaction constant was 0.0215. After 5 repeated use cycles, the degradation rate of TTCH was 85.21%. We also found that OH and O2− were produced in CN/001-ART after exposure to light, and the electrons of 001-ART were excited to the conduction band and combined with the holes in the valence band of CN, thus, forming a Z-type heterostructure. This resulted in the higher activity of CN/001-ART.

Fe, Mn-Prussian blue analogue@MXene composites for efficient photocatalytic peroxydisulfate-activated degradation of tetracycline hydrochloride and photoelectrochemical desalination

The utilization of wastewater or saline as a source of clean and safe freshwater is a potential solution to address water pollution and scarcity. In this study, we synthesized a composite material, i. e. Fe, Mn-Prussian blue analogue@MXene, which is highly responsive to visible light and serves as an innovative activator for peroxydisulfate (PDS) in the degradation of tetracycline hydrochloride (TCH). The FeMn-PBA@MXene-0.30 composite, with its unique metal-organic framework (MOF) structure, exhibited excellent photocatalytic activity in the degradation of TCH by activating PDS through dual redox cycles of Mn(II)–C≡N–Fe(III) and Mn(III)–C≡N–Fe(II). A remarkable 93.41% removal of TCH can be achieved at a concentration of 30 mg·L−1 within 120 min. The presence of MXene in the composite may facilitate the efficient electron transportation owing to its excellent conductivity. The influences of various reaction conditions are also investigated, such as the concentration of potassium persulfate (KPS), TCH concentration, and solution pH value. Electron spin resonance (ESR) analysis and trapping experiments revealed the presence of reactive species, including 1O2, ∙OH, and h+, in the FeMn-PBA@MXene-0.30/visible light/PDS system. Furthermore, we demonstrated the application of the FeMn-PBA@MXene-0.30 composite as the photoanode of a solar-assisted photoelectrochemical desalination (SA-PED) device, which combines the TCH degradation with photoelectrochemical desalination. This novel approach enabled simultaneous degradation and desalination, resulting in a significant reduction of 4000-ppm brine to 240 ppm (lower than the freshwater threshold of 500 ppm), with a salt removal efficiency (SRE) of 94.00%. Meanwhile, the degradation rate of TCH (900 mg·L−1) reached up to 98.91% under visible light irradiation. This work not only provides valuable insights into the development of PDS-activated catalysts but also explores new avenues for the multifunctional application of photocatalysts in addressing water pollution and scarcity.

Green synthesis of rectangular hollow tubular carbon nitride via in-situ self-assembly strategy to enhance the degradation of tetracycline hydrochloride under visible light irradiation

It has been an urgent requirement for materials with remarkable performance in the photocatalytic degradation of organic contaminants by photocatalytic technology. Limited surface area and speedy recombination rate of photogenerated charge carriers seriously restrain the application of g-C3N4. Morphology control is a powerful approach to enhance the photocatalytic efficiency of g-C3N4. Herein, we reported a method to attain graphitic carbon nitride with rectangular hollow tubular morphology and asperous surface (TUM–CN–2) which is prepared from urea-melamine hydrothermal products and trithiocyanuric acid by self-assembling without using organic solvents or template agents. The specific surface area, photocatalytic activity, and photo-generated carriers migration and separation rate of the obtained photocatalyst TUM–CN–2 are vastly improved. Contrasted with pure g-C3N4, the degradation rate of tetracycline hydrochloride (TCH) and Rhodamine B (RhB) was enhanced about 3.04 and 13.96 times in visible light irradiation, respectively. Moreover, the interference parameters, active free radicals, potential degradation mechanism, and degradation paths of TCH were researched systematically. This work provides a green way to acquire the modified g-C3N4 with splendid catalytic activity through the self-assembly method.

Preparation of a high-performance N-defect ZnO@g-C3N4 nanocomposite and its photocatalytic degradation of tetracycline

In this study, pure ZnO and N-deficient g-C3N4 (CN) were synthesized by co-precipitation method and simple calcination method, respectively. In addition, ZnO was impregnated on the surface of CN with mass percentages of 5, 10, 15, 20, 25 and 30 respectively. In addition, these materials were characterized by XRD, UV-Vis-DRS, TEM, SEM, PL and FT-IR. As a prepared material, the catalytic activity of tetracycline in wastewater was tested under visible light irradiation. The results showed that among all these catalysts, 10 wt% ZnO/g-C3N4 (ZN) showed better catalytic activity. When the mass ratio of ZN was 1: 10 and the calcination temperature was 550 ℃, the interlayer spacing, specific surface area and pore volume were larger, and the tetracycline removal rate and catalytic performance were the best. At the initial concentration of 20 mL/L and the addition of 50 mg catalyst, the degradation rate of tetracycline hydrochloride reached 93.47% within 120 min with ZN (0.10). The degradation rate reached nearly 100% at 80 min after adding H2O2. Advanced oxidation process can greatly promote the degradation of wastewater and has guiding significance in large-scale industrial application in the future.

Enhanced degradation of tetracycline hydrochloride with in situ prepared ferrate supernatant based on calcium hypochlorite: Compare with purified and commercial ferrate

Ferrate (Fe(VI)) salts are commonly regarded as green and high efficient oxidants to eliminate organic contaminants. Current studies mainly focused on develop homogeneous activation technology or heterogeneous catalysts to promote Fe(VI) performances in contaminants degradation. Interestingly, this study disclosed that the degradation performance of tetracycline hydrochloride (TC) was enhanced by using in situ prepared ferrate supernatant (Fe(VI)s), and the oxidation performance and degradation mechanism were systematically explored by comparing with the ferrate precipitation (Fe(VI)p) and the commercial ferrate (Fe(VI)c). Results showed that the degradation rate of TC by Fe(VI)s reached to 98.5 % within 5 min, while the degradation rate of Fe(VI)p and Fe(VI)c were obtained less than 20 % in 30 min. Although degradation process of TC in these three system were all conformed to the pseudo-first-order reaction kinetic, the rate of degradation (Kobs) obtained in Fe(VI)s was 5.30 and 37.2 times higher than that in Fe(VI)c and Fe(VI)p, respectively. Electron paramagnetic resonance (EPR), radical quenching and PMSO probe experiments proved that Fe(IV)/Fe(V) were the main active species for TC degradation with Fe(VI)s, while ∙OH and ⋅O2− were the main active substance of Fe(VI)c. On the basis of the intermediates detected by LC-MS/MS analysis, a pathway for TC degradation was proposed. In addition, the toxicity of TC and its degradation products was evaluated by using the toxicity evaluation software tool. This study demonstrated efficient organic contaminant oxidation with in situ prepared ferrate solution (Fe(VI)s) and provided a comprehensive understanding of degradation process for pollutants removal.

High-gravity photocatalytic degradation of tetracycline hydrochloride under simulated sunlight

Oxygen can generate reactive oxygen species in photocatalysis, promoting organic matter's mineralization. Therefore, enhanced oxygenation of the photocatalytic degradation system will help improve photocatalytic degradation efficiency. This study developed a novel high-gravity photocatalytic degradation method, which leverages the robust gas–liquid mass transfer capability of a supergravity rotating bed to realize the enhanced oxygenation of the photocatalytic degradation system. Specifically, this study used graphitic carbon nitride as the catalyst and tetracycline hydrochloride as the model pollutant. The effects of packing thickness, catalyst concentration, liquid flow rate, rotor speed, gas flow rate, and initial pH value on photocatalytic degradation performance were investigated. The results showed that the degradation rate of tetracycline hydrochloride reached 84.6 % under the optimal conditions of the rotating packed bed, which was 14.8 % higher than that of the traditional photocatalytic degradation process.

Microwave-Assisted Synthesis of MoS2/BiVO4 Heterojunction for Photocatalytic Degradation of Tetracycline Hydrochloride.

Compared with traditional hydrothermal synthesis, microwave-assisted synthesis has the advantages of being faster and more energy efficient. In this work, the MoS2/BiVO4 heterojunction photocatalyst was synthesized by the microwave-assisted hydrothermal method within 30 min. The morphology, structure and chemical composition were characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and high-resolution transmission electron microscopy (HRTEM). The results of characterizations demonstrated that the synthesized MoS2/BiVO4 heterojunction was a spherical structure with dimensions in the nanorange. In addition, the photocatalytic activity of the samples was investigated by degrading tetracycline hydrochloride (TC) under visible light irradiation. Results indicated that the MoS2/BiVO4 heterojunction significantly improved the photocatalytic performance compared with BiVO4 and MoS2, in which the degradation rate of TC (5 mg L-1) by compound where the mass ratio of MoS2/BiVO4 was 5 wt% (MB5) was 93.7% in 90 min, which was 2.36 times of BiVO4. The active species capture experiments indicated that •OH, •O2- and h+ active species play a major role in the degradation of TC. The degradation mechanism and pathway of the photocatalysts were proposed through the analysis of the band structure and element valence state. Therefore, microwave technology provided a quick and efficient way to prepare MoS2/BiVO4 heterojunction photocatalytic efficiently.

Yeast-derived biochar to load CoFe2O4: Degradation of tetracycline hydrochloride by heterogeneous activation of peroxymonosulfate

The development of high-efficiency catalysts is essential for activating peroxymonosulfate (PMS) to degrade organic pollutants. In this study, yeast-derived biochar (YBC) supported cobalt ferrite composite catalyst (CoFe2O4/YBC) was successfully synthesized, which can heterogeneous activate PMS to degrade tetracycline hydrochloride (TCH). The results showed that CoFe2O4/YBC could activate PMS effectively and stably owing to the synergistic effect of YBC and CoFe2O4. The degradation rate of TCH was nearly 95% under the optimal conditions, and it was still more than 90% after four cycles. Furthermore, according to quenching tests and electron paramagnetic resonance (EPR) detection, it was confirmed that ·OH, SO4·-, O2·-, and 1O2 were involved in TCH degradation, and 1O2 played a key role. After identifying the intermediates produced by TCH's degradation, two potential TCH degradation pathways were suggested. Further ECOSAR (2.0) software analysis revealed that the ecotoxicity of the final degradation products of TCH was small. This study demonstrates that the as-prepared CoFe2O4/YBC is an efficient and environmentally friendly PMS activation catalyst with great potential for application in the remediation of polluted aquatic environments.

Integration between CuMOF and g-C3N4 for effective suppressing charge recombination in photocatalytic peroxymonosulfate activation

In this work, CuMOF and graphite phase carbon nitride (g-C3N4) composite was synthesized, and tetracycline hydrochloride (TC) in water was degraded under simulated solar light irradiation with the assistance of peroxymonosulfate (PMS). The prepared g-C3N4/CuMOF samples were characterized by XRD, FT-IR, SEM, TEM and XPS. It is found that the introduction of CuMOF into g-C3N4 was not only beneficial to the charge separation of g-C3N4, but also greatly accelerated the activation of PMS. Through the initial pH value, PMS concentration, catalyst concentration, catalyst repeated use and other factors, the degradation performance of g-C3N4/CuMOF was studied. The photocatalytic experiment results showed that in the presence of PMS, the degradation rate of TC reached 90 % within 30 min. In addition, the reaction mechanism of the g-C3N4/CuMOF/PMS system was studied by using scavenging experiments and electron spin resonance (ESR) technology. This work provides a promising way for the rational design of high-performance and low-cost photocatalysts for environmental remediation.

Photocatalytic Degradation of Tetracycline Hydrochloride by Zinc oxide/Polypyrrole/Carbon nanotubes

AbstractIn this study, the intermediates of the photocatalytic degradation of tetracycline hydrochloride (TC‐HCl) were analyzed by high performance liquid chromatography‐mass spectrometry. The doping of polypyrrole (PPy) and carbon nanotubes (CNTs) increased the reaction rate of TC‐HCl degradation by ZnO. The prepared ZnO has a large specific surface area, which can improve the adsorption performance. The introduction of PPy and CNTs can promote electron transfer and reduce the recombination of photogenerated electron hole pairs in the composite material ZnO/PPy/CNTs(ZPC), and the photocatalytic performance of the composite sample is improved. In addition, the new visible light catalyst has strong degradation effect on TC‐HCl. Using tetracycline hydrochloride as a pollutant, the photocatalytic degradation performance of each sample was analyzed. After 240 min of photoreaction, the Degradation rate of TC‐HCl (DTC‐HCl) by ZnO was 24.1 %, while that by ZPC was 91.5 %. Meanwhile, the intermediates of photocatalytic degradation of TC‐HCl were analyzed by high performance liquid chromatography‐mass spectrometry. The peak intensity of TC‐HCl from adsorption equilibrium to the end of the photocatalytic reaction occurred at a retention time of about 10.05 min and decreased with the increase of the reaction time. This indicates that TC‐HCl is broken down into small molecules during the reaction. Through the analysis of intermediates and active species, the degradation pathway of tetracycline hydrochloride was deduced.

Novel 2D/1D Bi2O2Se/tubular g-C3N4 Schottky junction photocatalyst promoting electron transfer for efficient degradation of tetracycline hydrochloride

Poor visible light (VSL) absorption capacity and severe photogenerated carrier recombination rate are the two major problems limiting the application of g-C3N4 (CN). In this work, a novel 2D/1D Bi2O2Se/tubular g-C3N4 (TCN) Schottky junction photocatalyst was prepared by combining 2D Bi2O2Se with TCN at room temperature. The degradation rate of tetracycline hydrochloride (TCH) catalyzed by 5% Bi2O2Se/TCN composite was 85.3% within 30 min under VSL illumination, and the degradation kinetic constant reached 0.0570 min−1, which was 9.6, 3.3, and 21.9 times higher than those of CN (0.0059 min−1), TCN (0.0173 min−1), and Bi2O2Se (0.0026 min−1), respectively. When 2D Bi2O2Se was combined with TCN as a cocatalyst, the Schottky junction was formed at the interface, which could efficiently transfer the photogenerated electrons in TCN to Bi2O2Se for enhancing photocarriers separation. In addition, Bi2O2Se enhanced the VSL light absorption performance of TCN. The main active species produced by Bi2O2Se/TCN under VSL illumination were h+ and •O2−. Based on the results of LC-MS, a new degradation path of TCH catalyzed by Bi2O2Se/TCN was proposed. Therefore, this work proposed a novel Bi2O2Se/TCN Schottky junction photocatalyst for highly efficient removal of TCH.

Construction of a BaTiO3/tubular g-C3N4 dual piezoelectric photocatalyst with enhanced carrier separation for efficient degradation of tetracycline

One-dimensional tubular g-C3N4 (TCN) with piezoelectric properties was prepared by self-assembly and hydrothermal method, and BaTiO3/TCN composite with excellent dual piezoelectric properties was constructed by further hydrothermal reaction. The piezoelectric degradation rate of tetracycline hydrochloride (TCH) by TCN (18.2 %) within 60 min under ultrasonic vibration was about 2.8 times higher than that by bulk g-C3N4 (CN) (6.6 %). Furthermore, the BaTiO3/TCN composite, a dual piezoelectric photocatalyst, exhibited excellent piezoelectric photocatalytic activity with TCH degradation rate of 91.0 % within 60 min under visible light (VSL) illumination and ultrasonic vibration, which was higher than that of ultrasonic vibration (27.8 %) and VSL illumination (81.8 %). The polarization electric fields were formed in both TCN and BaTiO3 under ultrasonic vibration, which could maintain the built-in electric field strength between the heterojunction interfaces, accelerate the photogenerated carrier migration, and thus improve the separation efficiency to achieve the synergic catalytic effect of dual piezoelectric under VSL irradiation. This work demonstrated that TCN had better piezoelectric photocatalytic properties than CN, and the efficient pollutant removal performance of dual piezoelectric photocatalysis, which provided new ideas for the development of piezoelectric photocatalysts.

Novel La3+/Sm3+ co-doped Bi5O7I with efficient visible-light photocatalytic activity for advanced treatment of wastewater: Internal mechanism, TC degradation pathway, and toxicity analysis

Controlling semiconductor photocatalysts by doping rare-earth ions is an effective strategy to improve photocatalytic performance. Simple solvothermal and calcination methods were used to prepare La3+ and Sm3+ modified Bi5O7I nanomaterials. Some characterizations such as XRD, XPS, SEM, TEM, UV–vis, etc. were carried out to explore its structural composition and photoelectrochemical properties. The photocatalytic activity was investigated by simulating the degradation of TC and RhB under visible-light irradiation. The degradation results showed that the photocatalytic efficiency of 4S4L-Bi5O7I was the best among the samples with the 100% degradation rate of TC (Tetracycline hydrochloride) and 93% of RhB (Rhodamine B). The capture experiment and ESR test proved that the active substances that play a role in the photocatalytic degradation of pollutants were ·O2−, 1O2 and h+, and on this basis, the possible degradation mechanism was proposed. The final results showed that La/Sm co-doping expanded the light absorption range of Bi5O7I and improved the charge separation efficiency and the specific surface area. Besides, the surface defects were formed on the surface of Bi5O7I due to ion-doping, which could catch e− to promote the separation and transfer of carriers and improve the photocatalytic activity. LC-MS was used to analyze the possible degradation pathways of TC. And the toxicity of TC was also analyzed via T.E.S.T and Toxtree. The results showed comprehensive toxicity of TC was decreased by 4S4L-Bi5O7I so that the overall water pollution was reduced. This work can provide a reference for the subsequent development of bismuth-based photocatalysts.

Construction of 3D porous BiOBr/MIL-101(Cr) Z-scheme heterostructure for boosted photocatalytic degradation of tetracycline hydrochloride

The challenge for efficient photocatalysis lies in the adsorption, reuse capacity and charge separation. Herein, we constructed a Büchner funnel-like three-dimensional (3D) porous BiOBr/MIL-101(Cr) Z-scheme heterostructure with large specific surface area by immobilizing BiOBr on MIL-101(Cr) framework. The BiOBr/MIL-101(Cr) hybrids exhibited efficient charge separation and increasing adsorption capacity. Importantly, Bi and Cr atoms formed an electron donor-acceptor system, which benefits to induce internal electric field (IEF) to construct Z-scheme heterostructures for promoting charge transfer and separation. In addition, MIL-101(Cr) allows the continued growth of BiOBr in the presence of (001) direction, thus exposing more (001) facet of BiOBr, which helps the electron transfer from (110) to (001) and accelerates the carrier separation. Meanwhile, the formation of 3D pore structure endowed the BiOBr/MIL-101 (BM-35, which contained 35 wt% MIL-101) with twice higher adsorption capacity than pure BiOBr. Tetracycline hydrochloride (TC-HCl) was chosen as the target pollutant to evaluate the photocatalytic performance of the as-prepared BM-35 under visible light irradiation, 94 % degradation rate of TC-HCl was achieved over BiOBr/MIL-101(Cr) after 100 min and maintained at 84 % after 5 cycles. The small pores of MIL-101(Cr) only enable water molecules to pass through, while TC-HCl cannot enter its inner pores. Moreover, the formation of BiOBr by sheet stacking has large pores that capture target pollutants onto the highly active surface and decompose them. Benefiting from the distinctive 3D structure, an adsorption-degradation cycle system was formed, the difficulty of MOF desorption was effectively overcome.

FeIn2S4/Bi2MoO6 Z-scheme heterostructural composites efficiently degrade tetracycline hydrochloride under visible light

Antibiotics have gradually become a new pollutant in water, which seriously threatens human health. The development of efficient and easily recyclable photocatalysts is urgently needed to achieve water purification. Herein, a novel FeIn2S4/Bi2MoO6 Z-scheme heterostructural composite is successfully synthesized by a simple heat-shrinkable polymerization solvothermal method. When the doping FeIn2S4 mass fraction is 10%, the degradation rate of tetracycline hydrochloride (TCH) is the highest, reaching 83.25%, which is 1.97 and 2.38 times higher than that of pure FeIn2S4 and Bi2MoO6, respectively. After five consecutive cycles, the degradation rate still reached 72.35%, which has high photocatalytic stability. Combined with energy band structure analysis, active substance capture experiments and modeling with density functional theory calculations confirm the photocatalytic mechanism of Z-scheme heterostructure. This project proposes a promising and feasible method for the preparation of Z-scheme heterostructured photocatalysts.