Visible Light Absorption Capacity Research Articles

Preparation of direct Z-scheme heterojunction la-doped Bi2WO6/CdS with enhanced visible light absorption and its photocatalytic degradation of antibiotics

In this paper, a novel direct Z-scheme heterojunction La-Bi2WO6/CdS composed of 3-dimensional flower-like Bi2WO6 and hexagonally stacked succulent CdS was successfully designed and synthesized. The morphology, optical properties, element valence and crystal structure of the catalysts were systematically characterized. When the dosage of LBC-40 was 1.0 g/L, the degradation rate of oxytetracycline (OTC, 20 mg/L, pH = 6) was 85.28 %, under low visible light illumination (65 W energy saving lamp) for 120 min and the reaction kinetic constant (0.01336 min−1) was 2.50 and 1.56 times that of pure Bi2WO6 and La-Bi2WO6, respectively. Moreover, La-Bi2WO6/CdS showed good photocatalytic activity for other single antibiotics, mixed antibiotics and antibiotics from different water sources. The photocatalytic activity only decreased by 7.69 % after 3 cycles. Furthermore, the possible photocatalytic degradation pathway and photocatalytic mechanism of OTC were proposed. The excellent photocatalytic performance of La-Bi2WO6/CdS is for that the doping of La3+ and the construction of direct Z-scheme heterojunction enhances the visible light absorption capacity and separation efficiency of photogenerated electron-hole pairs. This paper reports a new method, which can provide a reference for the design and development of visible light responsive photocatalysts with excellent photocatalytic properties.

Identification of Crucial Photosensitizing Factors to Promote CO2 -to-CO Conversion.

The sensitizing ability of a catalytic system is closely related to the visible-light absorption ability, excited-state lifetime, redox potential, and electron-transfer rate of photosensitizers (PSs), however it remains a great challenge to concurrently mediate these factors to boost CO2 photoreduction. Herein, a series of Ir(III)-based PSs (Ir-1-Ir-6) were prepared as molecular platforms to understand the interplay of these factors and identify the primary factors for efficient CO2 photoreduction. Among them, less efficient visible-light absorption capacity results in lower CO yields of Ir-1, Ir-2 or Ir-4. Ir-3 shows the most efficient photocatalytic activity among these mononuclear PSs due to some comprehensive parameters. Although the Kobs of Ir-3 is ≈10 times higher than that of Ir-5, the CO yield of Ir-3 is slightly higher than that of Ir-5 due to the compensation of Ir-5's strong visible-light-absorbing ability. Ir-6 exhibits excellent photocatalytic performance due to the strong visible-light absorption ability, comparable thermodynamic driving force, and electron transfer rate among these PSs. Remarkably, the CO2 photoreduction to CO with Ir-6 can achieve 91.5 μmol, over 54 times higher than Ir-1, and the optimized TONC-1 can reach up to 28160. Various photophysical properties of the PSs were concurrently adjusted by fine ligand modification to promote CO2 photoreduction.

Synthesis of impregnants for dispenser cathodes via homogeneous-lyophilization: Phase structure, optical response and emission property of four aluminates

Dispenser cathodes are the most widely used electron emission source in vacuum electron devices. The impregnant is the source for producing active substances in the dispenser cathodes, which play an irreplaceable role. However, impregnants’ phase structure and optical response properties have yet to be systematically investigated. Herein, four aluminates were prepared as impregnants via homogeneous-lyophilization followed by calcination. Due to the unique preparation process, the elemental distribution of aluminates is exceptionally uniform. Based on the first-principles DFT calculations, the primary phases of the two aluminates 532 and 411 were confirmed to be (Ba0.61Ca0.39)3Al2O6 (P213) and (Ba0.75Ca0.25)4Al2O7 (Cmca). At the same time, α-Ba2ScAlO5 and β-Ba2ScAlO5 are the only phases of aluminates 411-0.75Sc and 411-1.25Sc, respectively. XPS confirmed two chemical states of Ba and Sc in the aluminates. FT-IR and 27Al NMR indicate that the aluminum-oxygen skeleton in all aluminates exists mainly as [AlO4] tetrahedrons, accompanied by a small amount of distorted [AlOx] (x = 5, 6) polyhedrons. The UV–visible light absorption capacity, band gap and intra-structural electron transfer capacity of all aluminates are determined by UV–Vis DRS and PL spectra. The dispenser cathodes impregnated with aluminates 532 and 411 have zero-field current densities of 5.3 A/cm2 and 14.3 A/cm2 at 1100°Cb, respectively. The dispenser cathodes impregnated with aluminate containing scandium have different space-charge-limited current densities, i.e., 29.48 A/cm2 for 411-0.75Sc and 13.66 A/cm2 for 411-1.25Sc at 1000°Cb. This work will provide more options for synthesizing and applying impregnants.

First-Principles Study of Electronic Structure and Optical Properties of Ni-Doped Bi4O5Br2

In this study, we comprehensively explored the electronic structure and optical properties of Ni-doped Bi4O5Br2 through first-principles computational calculations. By calculating its electronic structure and band characteristics, we investigated the impact of Ni doping on the photocatalytic performance of Bi4O5Br2. The computational results indicated that Ni doping significantly altered the band structure of Bi4O5Br2, leading to a reduction in the band gap width. The band gap for undoped Bi4O5Br2 was 2.151 eV, whereas the Ni-doped system exhibited a smaller band gap, directly indicating its enhanced visible light absorption capacity and facilitating the effective separation of photo-generated electron–hole pairs. Through analysis of 2D charge density maps, we observed changes in chemical bonding induced by Ni doping. The shortening of Ni-O bonds suggested increased bond strength, consistent with the observed reduction in cell volume. These findings provide a theoretical foundation for understanding the mechanisms behind the enhanced photocatalytic hydrogen production performance in Ni-doped Bi4O5Br2, offering valuable insights for the design and optimization of highly efficient photocatalytic materials.

Enhancing Commercially Iron Powder Electron Transport by Surface Biosulfuration to Achieve Uranium Extraction from Uranium Ore Wastewater.

The zero-valent iron (ZVI) has attracted increasing attention due to the enhanced reactivity of ZVI to uranium wastewater. However, ZVI practical application is hampered due to its susceptibility to oxidation and the formation of passivation layers during storage and in situ restoration. To address these issues, we used a biosulfuration approach to modify ZVI for application in uranium ore wastewater treatment. A series of physicochemical characterization tools and photoelectronic analyses showed that BS-ZVI considerably increased carrier separation efficiency and visible light absorption capacity, resulting in a significant photoassisted enhancement effect on uranium extraction. Accordingly, the uranium removal efficiency of BS-ZVI reached 91% within 60 min, and its maximum adsorption capacity was 336.3 mg/g. By analyzing the mechanism, the improved U(VI) removal performance was mostly responsible on the dissolution of the passivation layer on the surface of ZVI, the generation of Fe(II) and FeS, and the important role of Shewanella putrefaciens extracellular polymers (EPS). Overall, the BS-ZVI biohybrid merges with the high activity of ZVI, bio-FeS, and self-regeneration ability of bacteria, expanding a promising new approach for sustainable treatment of uranium mine wastewater.

USE OF GRAPHITIC CARBON NITRIDE – CDS – BIVO4 COMPOSITE FOR PHOTOCATALYTIC REDUCTION OF SODIUM CARBONATE TO FORMIC ACID

The conversion of CO2 into valuable chemicals and fuels serves as a promising route for mitigating the greenhouse effect of CO2 and meeting energy demands. The carbon atom in CO2 molecule exhibits the highest oxidation state and CO2 itself with the C–O bond strength of 364 kJ/mol is chemically stable, so it is difficult to be activated and requires a large amount of energy to undergo conversion. In general, the reduction of CO2 can be carried out by chemical methods, including catalyzed hydrogenation reduction, photocatalytic reduction, thermochemical reduction, electrochemical reduction etc. Influenced by “artificial photosynthesis”, different energy mimetic fuels such as formic acid, methane, etc. can be prepared by the reduction of carbon dioxide captured from the atmosphere while maintaining different reaction strategies, such as photocatalysis, and photo electrocatalysis. Graphitic carbon nitride (g-C3 N4 ) has been recognized as a highly potent photo- as well as electrocatalyst for the CO2 reduction reaction (CRR), primarily due to its high chemical and thermal stability, low toxicity, cost-effectiveness, visible light absorption capacity, and ingeniously tunable synthetic routes as compared to other semiconductor platforms.

Photocatalytic fuel cell assisted by Fenton-like reaction for p-Chloronitrobenzen degradation and electricity production through S-scheme heterojunction C3N5 modified TNAs photoanode: Performance, DFT calculation and mechanism

Photocatalytic fuel cell (PFC) is a promising technology to recover usable energy from wastewater through the degradation of pollutants, whereas the complex preparation procedures and high photogenerated carrier recombination efficiency of photoanode remains an urgent challenge to improve the PFC performance. Herein, PFC with S-scheme heterojunction C3N5/TNAs photoanode assisted by Fenton-like reaction (C3N5/TNAs-PFC-Fenton) system was built for p-Chloronitrobenzene degradation and electricity production. The working function confirmed the band bending of C3N5 and TNAs, and density functional theory calculations indicated the formation of internal electric field at heterojunction interface of C3N5 and TNAs, which promoted visible-light absorption capacity and charge transfer property of C3N5/TNAs photoanode. The incorporation of Fenton-like reaction into C3N5/TNAs-PFC-Fenton system could effectively enhance p-Chloronitrobenzene degradation and electricity production by participating in free radical chain reaction and stimulating electron transfer. The radical trapping experiments confirmed that •OH and photogenerated electron were main reactive species, and photogenerated hole, •O2− and 1O2 were also participated in p-Chloronitrobenzene degradation. The p-Chloronitrobenzene degradation pathway was interpreted and the overall toxicity of p-Chloronitrobenzene was relieved after treatment in C3N5/TNAs-PFC-Fenton system. The C3N5/TNAs-PFC-Fenton system exhibited fine universality for degradation of organic pollutants and electricity production.

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.

Synthesis of graphitic carbon nitride modified kaolin-carboxyl graphene for the degradation of pharmaceutical waste under sunlight.

Graphitic carbon nitride modified with kaolin-carboxyl graphene (g-C3N4/KG) was successfully synthesized using urea as the precursor and was applied for the photocatalytic degradation of pharmaceutical compound, "cefepime." Structural and optical characteristics of g-C3N4/KG were analyzed using various characterization techniques such as FT-IR, XRD, TEM, SEM, EDX, TG, BET, DRS, and PL. The PL studies confirmed that g-C3N4/KG catalyst exhibits strong charge separation and electron flow, and enhanced visible light absorption capacity was revealed by DRS studies. Studies on the active radical species demonstrate that superoxide and hydroxy radicals play a major role in the photocatalytic degradation of cefepime and dye pollutants. g-C3N4/KG showed the complete removal MB and 85% of degradation of cefepime under solar light irradiation time of 75min and 135min, respectively. Additionally, possible mechanism for the breakdown of the antibiotic cefepime was presented, along with identification of the intermediates produced during the degradation process. The study demonstrates that this novel photocatalyst could be utilized to remove dyes as well as medical wastes from water under solar light.

Nonthermal plasma induced NiS/UiO-66-NH2 for boosting visible-light photo-Fenton degradation of tetracycline hydrochloride

Heterojunctions constructed from metal organic frameworks (MOF) and metal sulfides are the potential candidates for solar-light driven photo-Fenton elimination of antibiotics from wastewater. To boost the solar-light induced photo-Fenton degradation of tetracycline hydrochloride (TCH) over UiO-66, NH2-functionlized UiO-66 (UiO-66-NH2) was in-situ loaded with NiS (NiS/NU-66) via the nonthermal plasma sulfurization. For comparison to UiO-66-NH2, NiS/NU-66 had the lower adsorption capacity while the higher photo-Fenton activity for TCH removal. The removal efficiency of NiS/NU-66 climbed and then declined with an increase in NiS content, and the best removal efficiency (84.92 ± 2.55 %) for 110 mg L−1 TCH solution was obtained by c-NiS/NU-66 in 150 min. The sulfur and oxygen defects as well as the plentiful functional groups over NiS/NU-66 were favorable for providing the abundant vacant sites of TCH adsorption and photons capture. In addition, the rapid separation and migration of photo-generated e−/h+ pairs were achieved at the tight junction interface between NiS and UiO-66-NH2, enlarging the visible-light absorption capacity. In NiS/NU-66-assisted photocatalytic system, H2O2 was efficiently convert to •OH by e− and Ni2+/Ni3+ couples in solar light region. Hence, •OH, •O2− and h+ played the vital roles in this photo-Fenton system.

Regulating the Content of Donor Unit in Donor-Acceptor Covalent Triazine Frameworks for Promoting Photocatalytic H2 Production.

Using their own triazine groups as natural receptors, the introduction of various donor units to construct donor-receptor configuration in covalent triazine frameworks (CTFs) has been shown to be an effective strategy to improve photocatalytic activity. In this work, the effect of donor unit content (D-content) on the photoelectric properties and photocatalytic activity of CTFs was thoroughly investigated. Four analogous CTFs with different D-content have been rationally designed and synthesized, in which the bithiophene (Btp) as the donor unit and triazine as the acceptor unit. And CTF-Btp with the highest D-content showed the best photocatalytic activity. The experimental and theoretical results indicated this improvement is attributed to stronger visible light absorption capacity and higher photoinduced charge carrier separation efficiency. This study elucidates the relationship between the structural features of CTFs with varying D-content and their photocatalytic activity, offering a promising strategy for developing efficient photocatalysts.

Cornstalk hydrochar produced by phosphoric acid-assisted hydrothermal carbonization for effective adsorption and photodegradation of norfloxacin

Hydrochars have been widely applied in removing pollutants from aqueous solutions. In this study, hydrochars synthesized by H3PO4-assisted hydrothermal carbonization (HC-xPs) were used to remove norfloxacin (NOR) from water through synergistic adsorption and photodegradation. HC-xPs showed the morphology of carbon microspheres with an average diameter of 0.3 μm. The specific surface area of the hydrochar carbonized with 5 mol/L H3PO4 (HC-5P) was 11.2 times higher than that of the pristine hydrochar (HC). Furthermore, phosphorus-containing functional groups were introduced to HC-5P, beneficial to its adsorption of NOR. The highest NOR adsorption was achieved on HC-5P with the maximum Langmuir capacity of 69.1 mg g−1, owing to multiple mechanisms including electrostatic effects, π-π interactions, hydrophobic interactions, and hydrogen bonding. Compared with HC, HC-5P also demonstrated increased visible light absorption capacity. The first-order rate constant of HC-5P on combined adsorption and photodegradation of NOR was 12.0 times of HC. The photodegradation intermediates were identified by HPLC-MS to understand NOR degradation pathways. This work can be extended to the preparation of low-cost and highly efficient hydrochars for adsorption and photodegradation of pollutants in water.

Dominant role of in defect on carrier distribution and photocatalytic activity for BiVO4

The bismuth vanadate samples (In-BiVO4) have been synthesized through sol-gel method. The typical XRD patterns of samples have revealed that the doped In ions could enter the lattice of BiVO4. The results indicate that doped In ions improve the photocatalytic properties of the BiVO4 for the degradation of methyl orange. The as-prepared In doped BiVO4 photocatalysts exhibit strong visible light absorption capacity than that of bare crystalline BiVO4. Density functional theory calculations show that doped indium ions can effectively promote the separation of photogenerated holes.

Hydrothermal synthesis of (m-t)BiVO4/g-C3N4 heterojunction for enhancement in photocatalytic degradation of imidacloprid

Bismuth vanadate (BiVO4) has gained significant attention as a photocatalyst due to lower band gap energy and its effectiveness in the degradation of both organic and inorganic pollutants. In this study, BiVO4 and nanocomposites of BiVO4 with g-C3N4 were synthesized by varying g-C3N4 compositions using hydrothermal technique. Thereafter the catalysts were assessed for the degradation and mineralization of imidacloprid (IMD). The catalysts were characterized using SEM, BET, XRD, UV-Vis DRS, photoluminescence spectroscopy, and XPS techniques to analyze the various properties for its effectiveness. XRD studies reveals the monoclinic as well as tetragonal phase in synthesized BiVO4 and its composite. In a UV-C light with an intensity of 15 W/m2 and at neutral pH, the degradation rate was significantly higher (94.2%) for BiVO4/g-C3N4 (90:10), denoted as BVCN10, compared to the bare BiVO4 nano-catalyst (83.2%) within a short period of 30 min. BVCN10 catalyst reported higher surface area, improved visible light absorption capacity, and lower electron-hole recombination, presence of monoclinic and tetragonal phases which might have enhanced its photocatalytic activity thereby accelerating degradation efficiency. Kinetic studies show that the degradation of IMD follows the first-order rate law with a rate constant (k) 0.11 min−1. Furthermore, BVCN10 can be used five times without losing catalytic activity, making it a reliable nanocatalyst with economic and environmental benefits.

Silver phosphate–bacterial cellulose nanocomposites as visible light photocatalyst for wastewater purification

Silver phosphate (Ag3PO4) nanoparticles were deposited on bacterial cellulose (BC) nanofibrils as an eco-friendly, efficient, and reusable visible light active photocatalyst. BC–Ag3PO4 nanocomposites (BCAgP) with different BC/Ag3PO4 weight ratios were prepared by solution-precipitation method. The nanocomposites were characterized by UV-Visible diffuse reflection spectroscopy, XRD, FTIR, BET, and FESEM. Highly crystalline Ag3PO4 nanoparticles were well entrapped inside nano fibrillated BC matrix and eventually deposited along the fibers. Photocatalytic activity of the BCAgP nanocomposites were investigated by dye degradation experiments under solar light. The composite with BC: Ag3PO4 weight ratio of 1:4 (BCAgP14) showed the highest photocatalytic efficiency compared to other weight ratios and pure Ag3PO4. The sample also shows good photocatalytic activity even after 4 runs indicating its photostability. Higher photocatalytic efficiency of BCAgP14 nanocomposite was explained due to optimum Ag3PO4 loading and higher visible light absorption capacity. Bacterial cellulose is supposed to improve the photocatalytic activity of silver phosphate by promoting the adsorption of dyes and extending the charge recombination time under visible light of Ag3PO4 photocatalyst.

Nb2O5-graphene heterojunction composite with ultrahigh photocatalytic activity for solar light driven photodegradation of ciprofloxacin

Poor visible light absorption capacity and intrinsic conductivity restrict many applications of Nb2O5 in photocatalysis. The paper describes one solution for synthesizing Nb2O5-graphene photocatalyst with functional graphene quantum dot (GQD). Firstly, Nb(V) was coordinated with GQD to form water-soluble complex. Then, it was bound to graphene sheet via π-π stacking, reduced with ascorbic acid to produce graphene oxide gel and annealed in N2 at 900 °C. The resultant Nb2O5 nanocrystals offer ultrasmall size of 8.8 ± 0.6 nm and good crystallinity. The introduction of GQD realizes the construction of heterojunction. This narrows bandgap energy of Nb2O5 and optimizes the band structure. The narrowed bandgap energy leads to an enhanced visible light absorption, and more negative conduction band potential and more positive valence band potential promote production of superoxide (•O2–) and hydroxyl radicals (•OH). Combination of graphene with GQD improves adsorption of ciprofloxacin, separation of generated electrons and holes and light absorption capacity. G-Nb2O5-900 exhibits an excellent photocatalytic performance for solar light driven photodegradation of ciprofloxacin. The photodegradation efficiency is more than 3.58 times under ultraviolet light radiation and 12.4 times under visible light radiation over pristine Nb2O5. G-Nb2O5-900 shows a broad application prospect in antibiotic treatment in environmental water.

Heterojunction photocatalyst FeS2/g-C3N5 for activating sulfites to degrade tetracycline: A stable degradation system based on heterogeneous processes

The UV/sulfite system is a promising source of •SO4− and/or •OH, but its application is largely limited by the use of UV light due to its high cost and high energy consumption. Graphite carbon nitride (g-C3N5), as a new photocatalytic material, has better visible light absorption capacity and narrower band gap than g-C3N4, which is expected to activate sulfite under visible light to solve this problem. Herein, a novel FeS2/CN heterojunction material based on g-C3N5 was constructed by hydrothermal in-situ synthesis method and successfully activated sulfite, which was confirmed by tetracycline degradation experiments in water. Under optimized conditions, the degradation rate of TC in 1 h reached 96%. The experimental results revealed that the FeS2/CN heterostructure enhances the absorption of visible light and inhibits the recombination of carriers, enabling more electrons and holes to be utilized. Holes play a major role in the degradation reaction, promote the sulfite chain reaction, and effectively regulate the cycle of Fe2+ and Fe3+ in the solution. Iron ion leaching is negligible and the degradation reaction remains stable at pH 5–9.

In-situ constructing amidoxime groups on metal-free g-C3N4 to enhance chemisorption, light absorption, and carrier separation for efficient photo-assisted uranium(VI) extraction

The development of inexpensive and efficient semiconductor catalysts for photo-assisted uranium extraction from seawater remains a huge challenge. Herein, we have successfully synthesized amidoxime-rich g-C3N4 (AO-C3N4) by simply amidoximing a cyano-rich precursor for photo-assisted uranium extraction from seawater. The amidoxime groups not only served as the U(VI) binding sites for efficient uranium adsorption, but also significantly improved the visible light absorption capacity and carrier separation efficiency via introducing defect energy level, resulting in the excellent photocatalytic activity for AO-C3N4 towards photo-assisted uranium extraction. In the process of photo-assisted uranium extraction, U(VI) was first adsorbed by the amidoxime groups on the AO-C3N4 and then reduced to U(IV), while (UO2)O2·2H2O and (UO2)O2·4H2O were further formed by the oxidation of U(IV) by superoxide radicals (·O2-). Moreover, the generated reactive oxygen species (ROS) under light endowed AO-C3N4 with outstanding antibacterial properties, preventing the limitation of uranium extraction capacity from marine biofouling.

Construction of Ag2CO3/ZnFe2O4/bentonite Z-type heterojunction photocatalyst and efficient degradation of norfloxacin

A novel Ag2CO3/ZnFe2O4/bentonite composite photocatalyst with a Z-type heterojunction was prepared using a solvothermal-in situ precipitation method. Under optimal conditions, with a mass ratio of ZnFe2O4 to bentonite at 1:1.5 and a mass ratio of Ag2CO3 to ZnFe2O4/bentonite at 1:3, the removal rate of norfloxacin (NOR) solution at 30 mg/L by Ag2CO3/ZnFe2O4/bentonite under visible light irradiation was found to be as high as 94.40% At the same time, the photocatalyst has good universality and reuse stability. The experimental results of photocatalyst characterization and mechanism exploration demonstrate that the photocatalytic activity of Ag2CO3/ZnFe2O4/bentonite is significantly enhanced, which can be attributed to the effective separation of electron-hole pairs, improvement in visible light absorption capacity, and enhancement of adsorption properties. The radical capture experiments revealed that h+ played a pivotal role in the photocatalytic degradation of NOR by Ag2CO3/ZnFe2O4/bentonite, while ·O2− and ·OH acted as secondary factors. Ultimately, a Z-type heterojunction electron transfer mechanism was proposed. This study proposes the Ag2CO3/ZnFe2O4/bentonite photocatalysts with excellent stability for the treatment of NOR.

Ultrasonic synthesis of controllable thin sheet-like BiPO4 assisted by ionic liquid and Bi-MOF with enhanced visible-light photocatalytic activity

Raw materials and synthesis strategies have great influence on the morphologies and optical properties of materials. In this study, ultrasonic synthesis of controllable thin sheet-like BiPO4 with an excessive visible-light response was synthesized, using Bi-based metal-organic frameworks (CAU-17) and ionic liquid [Omim]H2PO4 as raw materials. Compared with BiPO4-H (hydrothermal, solid rod shape) synthesized using inorganic salt, BiPO4-A (agitation, thin rod-like) and BiPO4-U (ultrasonic, thin sheet-like) have better visible-light absorption capacity and narrower band gap. Under visible-light, they could degrade 27.7 % (BiPO4-H), 73.0 % (BiPO4-A), and 76.3 % (BiPO4-U) tetracycline hydrochloride at 30 min, respectively. The speedy charge transfer at the photogenerated carrier interface, large specific surface areas, and improved light adsorption greatly enhance the photocatalytic performance. Cyclic experiments exhibit that the material has good photostability and repeatability. Finally, the feasible degradation mechanism of the material was proposed via a capture experiment. This paper provides a new technique for synthesizing BiPO4 or other photocatalysts, which can be used for high-efficiency wastewater purification under visible-light.