Photocatalytic Degradation Rate Research Articles

Structural and magnetic studies of Cobalt-Substituted copper ferrites for efficient photocatalytic dye degradation

In this work, cobalt-substituted copper ferrites with the composition CoxCu1-xFe2O4 (0.0 ≤ x ≤ 1.0) were synthesized using the sol–gel autocombustion method with citric acid as fuel. The influence of cobalt ion substitution (Co2+) on the structural, magnetic, optical, and photocatalytic properties was systematically studied. A range of characterization techniques, including X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), UV–visible spectroscopy, and vibrating sample magnetometry (VSM), were used to analyze the properties of the synthesized materials.XRD analysis revealed that the crystallite sizes of the samples ranged between 20–25 nm, with interplanar distances, bond lengths between cations, and crystallite size varying according to the degree of cobalt substitution. The formation of the spinel structure and the successful incorporation of cobalt ions into the lattice were confirmed by FTIR spectroscopy. Magnetic measurements showed that increasing the cobalt content enhanced the saturation magnetization while also influencing the Curie temperature and coercivity.The photocatalytic efficiency of the CoxCu1-xFe2O4 samples was evaluated for the degradation of Methylene Blue, Congo Red, and Malachite Green dyes under visible light irradiation. The photocatalytic degradation rates were strongly influenced by the copper-to-cobalt ion ratio, with cobalt-rich compositions demonstrating superior activity. The best photocatalytic performance was observed for intermediate cobalt concentrations (x = 0.4 and x = 0.6), where particle size and dielectric constant behavior led to efficient electron-hole separation and improved degradation rates. Methylene Blue decomposition was significantly enhanced in an alkaline medium (pH10) due to better adsorption and charge interaction between the dye and the photocatalyst surface. Fitting the experimental data to the Langmuir-Hinshelwood and Weibull models further highlighted the increased degradation rates with increasing pH and cobalt content, supporting the conclusion that cobalt-substituted copper ferrites are highly effective photocatalysts.

Biomass-derived activated carbon/cerium oxide nanocomposite as adsorptive photocatalyst for effective removal of carcinogenic dye

Semiconductor-based photocatalysts offer potential solutions for carcinogenic dye-related issues in water under light irradiation. However, their efficiency is affected by the recombination of photoelectrons and holes. The present study focuses on synthesizing biomass-derived activated carbon (AC), Cerium Oxide (CeO2), and AC/CeO2 (ACO) nanocomposites for toxic dye degradation. The physicochemical properties of samples were analyzed by XRD, SEM, EDX, TEM, UV–visible, Raman, XPS, and PL analysis. The photocatalytic performance of AC, CeO2, and ACO nanocomposites was evaluated under dark and light conditions for the removal of carcinogenic Rhodamine B (RhB). ACO nanocomposites exhibited adsorptive-photocatalytic performance, displaying unique adsorption and photocatalytic degradation rates due to their synergistic combination. Remarkably, the ACO-4 composite showed lower recombination of e−/h+ pairs, thereby exhibiting superior photocatalytic activity compared to other samples. The degradation rate constant under light was 0.1815 min⁻¹ with a half-life time of 3.81 min, whereas in dark, it was 0.0665 min⁻¹ with a half-life time of 10.42 min.

Harnessing natural light: Novel nanoheterojunction photocatalyst NaGdF4:Yb,Tm@TiO2/Cu2(OH)2CO3 for actual wastewater remediation

This study introduces NaGdF4:Yb,Tm@TiO2/Cu2(OH)2CO3 (UTCu), an innovative nanophotocatalyst designed to address global energy crises and water contamination issues. Our developed photocatalyst, NaGdF4:Yb,Tm@TiO2/0.5mol%Cu2(OH)2CO3 (UTCu0.5), demonstrated exceptional efficiency, degrading 96.3% of malachite green (MG) within 2 h under Xenon lamp irradiation. The photocatalytic degradation rate of UTCu0.5 surpassed those of UT, Cu2(OH)2CO3, and P25 (Commercial TiO2) by 3.3, 9, and 2.8 times, respectively. The process effectively mineralized MG into less harmful compounds, marking its potential for eco-friendly wastewater treatment. Furthermore, UTCu0.5 exhibited robust degradation capabilities across various organic dyes and maintained its efficacy in mixed dye systems. Detailed mechanistic analysis revealed that the ·OH and ·O2− radicals play pivotal roles in the degradation process, facilitated by the formation of heterojunctions that enhance carrier separation and photocatalytic performance. Theoretical studies supported the significance of S-scheme heterojunctions in boosting the photocatalytic activity of UTCu0.5. Additionally, the catalyst was effective in degrading organic pollutants in different water matrices under both Xenon lamp irradiation and direct sunlight. Remarkably, it achieved a 77.4% removal rate of NH4⁺-N in real municipal wastewater under natural sunlight, with a selective conversion rate of 95.3% to N2, underscoring its practical applicability in environmental remediation. This research not only progresses photocatalysis technology but also provides vital insights for enhancing natural condition wastewater treatment strategies.

Biosynthesis of gold and silver nanoparticle using water hyacinth (Eichhornia crassipes) extract for photocatalytic degradation of organophosphate and organochlorine pesticide

The study aimed to assess the efficiency of synthesized gold (Au) and silver (Ag) nanoparticles in the degradation of organochlorine and organophosphate pesticides through photocatalysis. The synthesis of gold and silver nanoparticles was achieved using Eichhornia crassipes (water hyacinth extract). Photocatalytic degradation tests were conducted on organochlorine and organophosphate pesticides using gold and silver nanoparticles, with the absorbance of the samples measured by a UV spectrophotometer. The photocatalytic degradation rates of organochlorine and organophosphate were determined, with varied concentrations of the synthesized nanoparticles. The results showed high degradation rates at lower concentrations (10–20 ppm), with degradations of 51.789%, 47.954%, 47.983%, 44.088%, 41.565%, and 36.749% for 25/75, 50/50, and 75/25 Au nanoparticle ratios, respectively. The results also revealed that higher degradation rates were observed at longer reaction times (70–80 minutes), with percentage degradations of 44.344% and 49.987%, 41.754% and 45.937%, 36.773% and 40.458% for 25/75, 50/50, and 75/25 Au nanoparticle ratios, respectively. Lower degradation efficiencies were observed at shorter reaction times (10–20 minutes), with percentage degradations of 15.356% and 19.982%, 13.746% and 17.082%, and 10.976% and 15.167% for 25/75, 50/50, and 75/25 ratios, respectively. Additionally, the results showed high degradation rates at lower concentrations (10–20 ppm) for Ag nanoparticles, with percentage degradations ranging from 40.814% to 44.822% across AgNP ratios (25/75, 50/50, 75/25), indicating efficient degradation at lower concentrations. Conversely, at higher concentrations (60–80 ppm), the degradation efficiency was notably lower, with percentage degradations ranging from 7.004% to 13.539% across different AgNP ratios. In conclusion, Au nanoparticles exhibited higher photocatalytic efficiency than Ag nanoparticles, particularly in degrading organophosphate (Sniper) pesticides. It is recommended that these synthesized nanoparticles be considered as environmentally friendly and cost-effective options for pesticide degradation.

Investigation of Bi2MoO6/MXene nanostructured composites for photodegradation and advanced energy storage applications

This study presents nanostructured composite Bi2MoO6/MXene heterostructure by using hydrothermal method for photodegradation of the congo-red dye and also for energy storage devices. X-ray diffractometer (XRD), High Resolution Transmission Electron Microscopy (HRTEM), Field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) were performed to examine the structural properties along with surface area and porosity of the material. Due to addition of MXene the larger surface area and improved pore size help to quickly break down additional organic pollutants by adsorbing them. The band gap of Bi2MoO6/MXene nanostructured composite reduced to 2.4 eV suggesting transfer of electrons from VB to CB. Bi2MoO6/MXene exhibits a high (92.3%) photocatalytic degradation rate for a duration of 16 min which was verified using UV-visible spectroscopy, also scavenger test was conducted to ascertain the reactive agent along with the degradation pathway was confirmed by LCMS. Elemental content was also established by using inductively coupled plasma mass spectrometry (ICP-MS). For estimating energy storage capacity cyclic voltammetry (CV) was performed. It was observed Bi2MoO6/MXene nanostructured composite electrodes had specific capacitance of 642.91Fg− 1, power density of 1.24 kWkg− 1, and energy density of 22.32 Whkg− 1 at a current density of 5Ag− 1 also it exhibited 64.42% capacity retention having current density 20 Ag− 1 throughout 10,000 Galvanostatic charge discharge (GCD) cycles. High electrical conductivity of Bi2MoO6/MXene electrode was again examined by Electrochemical impedance spectroscopy (EIS). These findings demonstrate the potential of Bi2MoO6/MXene nanostructured composites in both photodegradation and energy storage applications.

Amorphous titanium dioxide with synergistic effect of nitrogen doping and oxygen vacancies by photoexcited sol-gel preparation for enhanced photodegradation of tetracycline

In this paper, a novel N-doped amorphous titanium dioxide (N20AT-hν) photocatalyst was prepared by the sol–gel route in which the sol added with salicylaldehyde hydrazone undergoes gel after photoexcitation. Based on a systematic exploration of as-prepared catalysts, it is known that N20AT-hν sample has a particle size of 50–60 nm, a specific surface area of 294.699 m2 g−1, and which is doped with nitrogen elements and forms abundant oxygen vacancies (OVs). The photocatalytic degradation rate of N20AT-hν for 20 mg L−1 tetracycline solution reached 92.23 % after 60 min, and the rate exhibited a slight decrease of 8.68 % after five cycles. Reactive species trapping experiments and electron spin resonance techniques indicate that superoxide radicals and holes are instrumental in photocatalytic degradation. Possible mechanism of forming the active species through OVs mediated traps and electron transfer pathways has been proposed. Furthermore, the predictive evaluations suggest that the degradation of tetracycline solutions by N20AT-hν sample results in less harmful decomposition product.Benefiting from the environmental friendliness of preparation method and the superiority of elemental doping, N20AT-hν material with synergistic effects has great potential for environmental applications.

Incorporating ReS2 Nanosheet into ZnIn2S4 Nanoflower as Synergistic Z-Scheme Photocatalyst for Highly Effective and Stable Visible-Light-Driven Photocatalytic Hydrogen Evolution and Degradation.

Inspired by natural photosynthesis, the visible-light-driven Z-scheme system is very effective and promising for boosting photocatalytic hydrogen production and pollutant degradation. Here, a synergistic Z-scheme photocatalyst is constructed by coupling ReS2 nanosheet and ZnIn2S4 nanoflower and the experimental evidence for this direct Z-scheme heterostructure is provided by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance. Consequently, such a unique nanostructure makes this Z-scheme heterostructure exhibit 23.7 times higher photocatalytic hydrogen production than that of ZnIn2S4 nanoflower. Moreover, the ZnIn2S4/ReS2 photocatalyst is also very stable for photocatalytic hydrogen evolution, almost without activity decay even storing for two weeks. Besides, this Z-scheme heterostructure also exhibits superior photocatalytic degradation rates of methylene blue (1.7 × 10-2 min-1) and mitoxantrone (4.2 × 10-3 min-1) than that of ZnIn2S4 photocatalyst. The ultraviolet-visible absorption spectra, transient photocurrent spectra, open-circuit potential measurement, and electrochemical impedance spectroscopy reveal that the superior photocatalytic performance of ZnIn2S4/ReS2 heterostructure is mostly attributed to its broad and strong visible-light absorption, effective separation of charge carrier, and improved redox ability. This work provides a promising nanostructure design of a visible-light-driven Z-scheme heterostructure to simultaneously promote photocatalytic reduction and oxidation activity.

Photocatalytic Degradation of Ciprofloxacin HCl using Visible Active BiOS Photocatalyst and Artificial radiation

Ciprofloxacin, a potent biologically active substance, has caused significant environmental issues when present in natural waters. The current study aimed to investigate the visible lightinduced degradation of ciprofloxacin HCl (CFX) using bismuth oxysulfide (BiOS) as a photocatalyst. A new photocatalyst BiOS has been developed and tested for the photocatalytic degradation (PCD) of pharmaceutical pollutants in wastewater using artificial radiation. Specifically, this novel material was examined for its ability to degrade ciprofloxacin HCl (CFX). A nanocomposite of BiOS photocatalyst has been synthesized utilizing the sol-gel method and subsequently characterized using UV-DRS, SEM, and EDAX techniques. A tungsten lamp was utilized to simulate artificial radiation during the PCD of CFX. Based on studies on the ideal operating conditions for the BiOS photocatalyst, the maximum rate of photocatalytic degradation (PCD) was reached at a neutral pH of 7. When compared to a saltfree environment, the rate of PCD was observed to be increased by anionic salts (NaCl, Na2CO3, and (NH4)2SO4). The Cland CO3- ions have notably increased the rate of PCD than SO4- ions. According to Langmuir-Hinshelwood kinetic modeling, the PCD of CFX exhibits a pseudo-first-order reaction behavior. Therefore, it can be said that BiOS is a suitable photocatalyst for treating wastewater from pharmaceutical plants.

Efficient Degradation of Methyl Violet 10B Dye by Different Light Sources using Boron-doped TiO2-ZnO Photocatalyst

Boron-doped TiO2-ZnO nanocomposite was prepared by sonochemically using boron trichloride, tetra n-butyl orthotitanate and zinc acetate in appropriate proportion. The as-prepared nanocomposite was successfully characterized by XRD, EDX, SEM and BET techniques The operational factors that affect the rate of photocatalytic degradation of methyl violet 10B present in wastewater were optimized, which include initial dye concentration, catalyst amount, pH level and different light intensities such as incandescent light bulb, UV lamp and sunlight. During sonication under sunlight, it was found that the most effective removal rate achieved was 95% when using 0.02 g of B doped TiO2-ZnO per 100 mL of methyl violet 10B solution. The impact of different dye concentrations on the photocatalytic degradation demonstrated the threshold at which concentrations may be readily eliminated. The most effective pollutant degradation was achieved at 5 ppm. The introduction of oxygen using sonophotocatalysis process into the polluted stream enhanced the photocatalytic breakdown of the pollutants. The photocatalyst can be recycled for four cycles without loss the catalyst stability and the degradation rate obeys first-order kinetics.

Modulation of the Microstructure and Enhancement of the Photocatalytic Performance of g-C3N4 by Thermal Exfoliation

This work explores the impact of reaction temperature during thermal exfoliation treatment of bulk-g-C3N4 in the air atmosphere on the structure and performance of the resulting CN photocatalyst. The analysis conducted using XRD, FT-IR, XPS, SEM, and elements mapping tests, illustrated an increase in nitrogen-vacancy and oxygen content on the surface of the CN photocatalyst, resulting in a porous and sparse structure, changes in crystal size, and improved visible light absorption performance. The photocatalytic reduction experiments of hexavalent chromium (Cr(VI)) showed that the CN-540 showed the highest reduction rate of 96.9%, with a reaction rate constant 6.21 times that of bulk-g-C3N4. After 100 min of illumination, the photocatalytic degradation rates of CN-540 for TC-HCl and RhB were 66.7% and 60.6%, respectively. The TOC test results indicated mineralization rates of 51.5% for TC-HCl and 46.6% for RhB. Room temperature fluorescence spectroscopy (PL), transient photocurrent response (TPC), and electrochemical impedance spectroscopy (EIS) measurements confirmed the excellent photogenerated charge carrier separation and transport efficiency of CN-540. The photocatalytic mechanism for reducing Cr(VI) by CN-540 was elucidated based on the active species •OH and •O2– and Mott-Schottky (M-S) tests. This study provides experimental data for optimizing the photocatalytic performance of g-C3N4 and paves a new way for developing efficient photocatalysts. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Ag@AgCl/carbon nitride/graphene oxide three-dimensional nanocomposite constructed for efficient removal of organic dyes by synergistic adsorption-photocatalysis

The efficient removal of dye pollutants from wastewater is a significant and hotspot research. In this manuscript, Ag@AgCl nanoparticles were anchored on three-dimensional carbon nitride/graphene oxide (CN/GO) using an in-situ photoreduction strategy, and thus a novel (Ag@AgCl/CN/GO) was achieved. The results showed that the Ag@AgCl/CN/GO was a highly efficient adsorption and photocatalytic material for the removal of dye pollutants. The maximum adsorption capacity of malachite green (MG), methylene blue (MB), rhodamine B (RhB) and crystal violet (CV) can be reached as 324, 216, 148 and 112 mg g−1, and the photocatalytic degradation rate were 95 %, 83 %, 76 % and 93 % under irradiation for 60 min, which were greatly higher than some comparisons reported. The improved visible light, enhanced absorption and electron transfer in the Ag@AgCl/CN/GO three-dimensional structure were responsible to the highly efficient removal of dyes. Furthermore, the Ag@AgCl/CN/GO showed a good reusability in the cycling test. The constructed nanocomposite will be attractive for removing pollutants in wastewater.

Photocatalytic degradation of phenol and polycyclic aromatic hydrocarbons in water by novel acid soluble collagen-polyvinylpyrrolidone polymer embedded in Nitrogen-TiO2

The photocatalytic degradation of phenol, naphthalene, fluoranthene, phenanthrene, pyrene, benz[a]anthracene, and anthracene was investigated using a novel nitrogen-doped TiO2/acid-soluble collagen-polyvinyl pyrrolidone nanocomposite (N-TiO2/ASC-PVP). Characterization through X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) revealed that the nanocomposite consists of spheroidal particles smaller than those of undoped TiO2. X-ray photoelectron spectroscopy (XPS) confirmed the incorporation of nitrogen within the TiO2 lattice, appearing as both substitutional nitrogen (OTiN) and interstitial nitrogen (TiON). The degradation process followed apparent first-order kinetics, with the N-TiO2/ASC-PVP calcined at 200°C and 400°C demonstrating high photocatalytic degradation efficiencies. The nanocomposite achieved a remarkable 98.6% degradation of the targeted compounds within 120 minutes at a concentration of 10 mg/L. The enhanced photocatalytic activity under visible light can be attributed to several factors: the smaller crystal size, increased surface hydroxyl groups, improved visible light absorption, and a reduced band gap energy. This N-TiO2/ASC-PVP photocatalyst shows significant potential for applications in materials science and nanotechnology, supporting advancements in environmental and energy-related fields.

Mn doping and ZnS nanoparticles modification on Bi2MoO6 to achieve an highly-efficient photocatalyst for TC degradation

Environmental pollution presents significant challenges to both human production and daily life. Photocatalytic technology offers a promising solution for environmental remediation, and Bi2MoO6 is widely recognized as an excellent visible light photocatalyst for the degradation of organic pollutants. Nevertheless, the high recombination rate of photogenerated charge carriers in Bi2MoO6 limits the number of charge carriers available for photocatalytic reactions, resulting in reduced photocatalytic efficiency. To overcome this limitation, we designed and synthesized a composite photocatalyst (30% ZnS/Mn0.08-Bi2MoO6). Mn-doped Bi2MoO6 nanosheets (Mn-Bi2MoO6) were prepared through a simple coprecipitation method, and ZnS nanoparticles were introduced to modify the surface, forming a ZnS/Mn-Bi2MoO6 composite photocatalyst. Experimental results demonstrated that the photocatalytic degradation rate of tetracycline using the 30% ZnS/Mn0.08-Bi2MoO6 composite increased 11.1 times and 3.7 times compared with pure Bi2MoO6 and ZnS, respectively. The formation of ZnS/Mn-Bi2MoO6 heterojunction was confirmed through XRD, XPS, SEM, and TEM analyses. Furthermore, photoelectrochemical measurements, including photocurrent, EIS, and PL, indicated that Mn doping and the ZnS nanoparticle modification significantly improved the separation and transfer efficiency of photogenerated charge carriers. DFT calculations and experimental results revealed the photocatalytic mechanism of the 30% ZnS/Mn0.08-Bi2MoO6 composite. This study provides valuable theoretical and technical insights into photocatalyst modification.

Synthesis of a novel Bi19Cl3S27/Bi2MoO6 Z-type heterojunction for efficient photocatalytic removal of tetracycline antibiotic and Cr(VI): Intermediate toxicity and mechanism insight

Novel Bi19Cl3S27/Bi2MoO6 (BCS/BMO) Z-type heterojunctions were synthesized using a straightforward hydrothermal method. Benefiting from the large specific surface area (62.41 m2/g) and the effective separation of photogenerated carriers facilitated by the Z-scheme heterojunction, the BCS/BMO exhibited remarkable improved photocatalytic tetracycline degradation and Cr(VI) reduction efficiency in comparison to BCS, BMO, and their physical mixture. Specifically, the photocatalytic degradation rate constants for TC and Cr(VI) are 0.0209 and 0.0218 min−1, respectively, which are 16.08 and 15.57 times those of BCS, 1.74 and 1.31 times those of BMO, and 2.4 and 1.73 times those of the physical mixture. Additionally, based on density functional theory (DFT) calculations and empirical data, three potential photocatalytic pathways of tetracycline were presented. This study presents a novel approach for designing and synthesizing high-efficiency Z-scheme photocatalysts for the degradation of TC and the reduction of Cr(VI) in wastewater.

Sonochemical preparation of powerful S-scheme Zr(HPO4)2/g-C3N4 heterojunction for photocatalytic degradation of rhodamine B under natural solar radiations

An effective Zr(HPO4)2/g-C3N4 S-scheme heterojunction was synthesized by sonochemical coupling of Zr(HPO4)2 nanoparticles as an oxidative photocatalyst [EVB = +3.0 eV] with g-C3N4 nanosheets as an effective reductive photocatalyst [ECB = −1.25 eV] for photocatalytic degradation of rhodamine B dye under natural solar radiation of 1000 W power. The physicochemical properties of the as-synthesized heterojunctions were investigated by X-ray diffraction [XRD], N2-adsorption-desorption isotherm, diffuse reflectance spectrum [DRS], photoluminescence [PL], scanning electron microscope [SEM], X-ray photoelectron spectroscope [XPS], and high resolution transmission electron microscope [HRTEM]. The experimental results implied the agglomeration of Zr(HPO4)2 nanoparticles on g-C3N4 sheets which reduced the specific surface area of the solid specimen from 88 to 21 m2/g. The significant increase in the photocatalytic degradation rate of RhB dye with introducing Zr(HPO4)2 nanoparticles implied that Zr(HPO4)2 plays a crucial role in reducing the band gap energy and remarkable increasing in the rate of electron-hole separation. The photocatalytic experiments implied that incorporation of 5 wt% Zr(HPO4)2 on g-C3N4 sheets destroyed 98 % of RhB dye during 3 h of light illumination with pseudo-first-order rate of 0.048 min−1. The remarkable enhancement in the photocatalytic performance of Zr(HPO4)2/g-C3N4 heterojunctions was ascribed to successful generation of an effective S-scheme heterojunction with strong redox power, utilizing of both hydroxyl and superoxide radicals in the degradation process and limiting the electron-hole recombination rate. Based on scavenger experiments and terephthalic acid PL analysis, the S-scheme pathway was chosen as the proposed mechanism for photocatalytic charge transfer. The as-synthesized Zr(HPO4)2/g-C3N4 heterojunction with exceptional redox power is considered a novel candidate for destructing organic pollutants that exist in industrial wastewater.

Enhanced photocatalytic performance of TiO2 with tunable oxygen vacancies induced by H2/N2 mixture treatment

Surface treatment can effectively modulate the surface properties of a photocatalyst to hasten the separation and transfer of photoinduced charges, ultimately achieving high photocatalytic performance. Herein, surface treatment of anatase-phase TiO2 prepared by a hydrothermal method was performed under H2/N2 mixed atmosphere. The experimental results demonstrate that roasting TiO2 in a H2/N2 atmosphere can effectively reduce partial Ti4+ to Ti3+, thereby facilitating the production of tunable oxygen vacancies (OVs) by disrupting Ti-O-Ti bonds. OVs can construct defective energy levels to bring about a decrease in the bandgap of TiO2 and an extension of light absorption range. Moreover, OVs remarkedly improve the separation of photoinduced charges of TiO2 and accelerate the photocatalytic reaction as active sites. The photocatalytic experimental results demonstrate that TiO2 exhibits the highest performance when roasting TiO2 in a H2/N2 atmosphere for 2 h, and the photocatalytic degradation rate constant of rhodamine B (RhB) and tetracycline (TC) on this sample under simulated solar light irradiation is 2.24 and 1.11 times higher than that on the reference TiO2, respectively. These findings provide valuable insights for designing highly efficient photocatalysts for effective water pollution treatment.

Titania stabilized Pickering emulsion for photocatalytic degradation of o-xylene

Efficient removal of insoluble volatile organic compounds (VOCs) from wastewater is a significant environmental challenge. In this work, we exploit the synergistic effect of photocatalysis and the high interfacial area of TiO2-stabilized Pickering emulsion to achieve efficient degradation of o-xylene, typically present in wastewater discharged from many industries. Interfacial photocatalysis is carried out by considering o-xylene in water Pickering emulsions stabilized by commercial titania nanoparticles in a multitube non-stirred reactor setup. Stable emulsions used for catalysis are formulated by optimizing o-xylene volume fraction, TiO2 concentration, pH, and homogenization conditions. The influence of photocatalyst loading, emulsion droplet size, and reaction conditions are systematically examined to determine their influence on the rate of photocatalytic degradation of o-xylene. Due to enhanced photocatalytic activity compared with conventional stirred batch photocatalysis, the TiO2-stabilized Pickering emulsion is found to increase the degradation rate and removal efficiency of o-xylene significantly. Furthermore, the Pickering emulsion stability during the photocatalytic process is studied, demonstrating the capacity of the emulsions to maintain stability and catalytic activity over a longer time period. The distinctive characteristics of Pickering emulsions – excellent storage stability and enhanced photocatalytic activity – make them a promising option for advanced wastewater treatment. The findings lead to the development of ecologically acceptable and sustainable VOC degrading strategies, which might be used in industrial and home wastewater treatment systems.

Visible-light-driven photocatalytic for degrading tetracycline wastewater by BiOI/Bi2O3 Z-scheme heterojunction

Direct Z-scheme heterojunctions can exhibit enhanced redox capacity in redox reactions compared to conventional heterojunctions. In this study, BiOI/Bi2O3 Z-scheme heterojunctions were synthesized by a facile co-precipitation and calcination method using BiOI as a precursor, and its photocatalytic activity was investigated by degrading tetracycline antibiotics in aqueous environment. Under visible light, the degradation efficiency of tetracycline reached 80.01 % and the photocatalytic degradation rate constant reached 0.0116 min−1 when the molar ratio of Bi and I in BiOI/Bi2O3 composites was 1:1, which were 2.8 and 4.8 times higher than that of pristine BiOI (0.0041 min−1) and Bi2O3 (0.0024 min−1), respectively. The heterojunctions exposed excellent stability that maintained at 78.80 % after four cyclic tests. The ascendant photocatalytic performance can be attributed to the formation of direct Z-scheme heterojunctions, which improves the separation and transfer efficiency of the photogenerated electron-hole pairs, and ·O2- is the main active substance in the degradation process. This research provides a green and convenient method for preparing photocatalytic heterojunctions, which is conducive to promoting the development of photocatalytic degradation of refractory pollutants under visible light.

Design and fabrication of ellipsoidal α-Fe2O3@SnO2 core-shell microspheres with heterostructures for improving photocatalytic performance

α-Fe2O3@SnO2 core–shell microspheres with heterostructures were successfully designed and fabricated using Na2SnO3·4H2O as the tin source. The influence of Sn/Fe molar ratio and calcination temperature on the morphology and structures of α-Fe2O3@SnO2 microspheres were systematically investigated. For the Sn/Fe molar ratio between 0.5 and 1.0, the optical absorption capacity of α-Fe2O3@SnO2 microspheres is higher than that of pure SnO2 because of the heterostructures. With increasing the calcination temperature, the degree of crystallization and specific surface area of α-Fe2O3@SnO2 microspheres also are progressively improved. The photocatalytic performance for Rhodamine B (RhB) degradation was subsequently assessed under sunlight-like irradiation. After calcination at 600 °C, the Fe/Sn-0.75 sample demonstrates the significant acceleration of photocatalytic degradation rates. The photocatalytic degradation rate under light irradiation after 8 h reaches 93.30 % and maintains at 89.98 % even after five cycles.

Using Er/Cd-Codoped Bi4O5Br2 Microspheres to Enhance Antibiotic Degradation under Visible Illumination: A Combined Experimental and DFT Investigation.

High levels of antibiotic accumulation and the difficulty of degradation can have serious consequences for the environment and, therefore, require urgent attention. To solve this problem, a synergistic Er and Cd ion-codoped Bi4O5Br2 photocatalyst was proposed. The degradation rate of sulfamethoxazole (SMX) by Er/Cd-Bi4O5Br2 was eight times higher than that of pure Bi4O5Br2, exceeding that of single Er-doped or Cd-doped Bi4O5Br2, which was attributed to the ability of Er/Cd-Bi4O5Br2 to generate a variety of free radicals. Experimental results and theoretical calculations suggested a possible mechanism for the improved photocatalytic degradation rate. The reduction of the band gap can facilitate the production of electron-hole pairs, which play a significant role in the production of reactive radicals. Furthermore, an optimal stabilized structure of the ErCd-Bi4O5Br2 dopant system was identified based on the formation energy formulas of different ligand configurations. These findings offer promising potential for the degradation of broad-spectrum antibiotics and provide valuable insights for the design and modification of photocatalytic materials.