Photocatalytic Degradation Process Research Articles

Sono-assisted photocatalytic degradation of ciprofloxacin in aquatic media using g-C3N4/MOF-based nanocomposite under visible light irradiation.

This research study is centered on the sono-assisted photocatalytic degradation of a well-known antibiotic (ciprofloxacin; CIP) in aquatic media using a g-C3N4/NH2-UiO-66 (Zr) catalyst under visible light irradiation. Initially, the catalyst was prepared by a simple method, and its physiochemical features were thoroughly analyzed by XRD, FT-IR, FE-SEM, EDX, EDS-Dot-Mapping, and UV-Vis analytical techniques. After that, the impact of several influential factors affecting the performance of the applied sono-assisted photocatalytic process such as the initial concentration of CIP, solution pH, catalyst dosage, light intensity, and ultrasound power was fully assessed, and the optimal conditions were established. After 75min of the sono-assisted photocatalytic treatment, the complete degradation of CIP (10mg/L) was accomplished under the condition as follows: g-C3N4/NH2-UiO-66 (Zr), 0.6g/L; pH, 5.0, and ultrasound power, light intensity 75 mw/cm2, 200 W/m2. Meanwhile, the photocatalytic degradation of CIP followed the pseudo-first-order kinetic model. In addition, the scavenger experiments demonstrated that OH˚ and O2°- radicals played a key role in the sono-assisted photocatalytic degradation process. It is also acknowledged that the applied catalyst was reused for five consecutive runs with a minor loss observed in its degradation efficiency. In a further experiment, a significant synergistic effect with regard to the degradation of CIP was observed once all three major parameters (visible light, ultrasound waves, and catalyst) were used in combination compared to each used alone. To sum up, it is thought that the integration of g-C3N4/MOF-based catalyst, ultrasound waves, and visible light irradiation could be potentially applied as a promising strategy for the degradation of various pharmaceuticals on account of high degradation performance, simple operation, excellent reusability, and eco-friendly approach.

Recent Advancement in Emerging MXene-Based Photocatalytic Membrane for Revolutionizing Wastewater Treatment.

MXene-based photocatalytic membranes provide significant benefits for wastewater treatment by effectively combining membrane separation and photocatalytic degradation processes. MXene represents a pioneering 2D photocatalyst with a variable elemental composition, substantial surface area, abundant surface terminations, and exceptional photoelectric performance, offering significant advantages in producing high-performance photocatalytic membranes. In this review, an in-depth overview of the latest scientific progress in MXene-based photocatalytic membranes is provided. Initially, a brief introduction to the structure and photocatalytic capabilities of MXene is provided, highlighting their pivotal role in promoting the photocatalytic process. Subsequently, in pursuit of the optimal MXene-based photocatalytic membrane, critical factors such as the morphology, hydrophilicity, and stability of MXenes are meticulously taken into account. Various preparation strategies for MXene-based photocatalytic membranes, including blending, vacuum filtration, and dip coating, are also discussed. Furthermore, the application and mechanism of MXene-based photocatalytic membranes in micropollutant removal, oil-water separation, and antibacterial are examined. Lastly, the challenges in the development and practical application of MXene-based photocatalytic membranes, as well as their future research direction are delineated.

Construction of Z‐scheme 1T/2H‐MoS2/CdS for improving photocatalytic degradation of antibiotic residues

Abstract1T/2H‐MoS2/CdS composite was effectively prepared by a two‐step hydrothermal method, which greatly improved the photocatalytic degradation efficiency of tetracycline hydrochloride and photocatalytic cycle stability compared with pristine 1T/2H‐MoS2. The highest photodegradation efficiency of 70.8% is achieved when the molar ratio of 1T/2H‐MoS2 to cadmium sulfide is 1:4. The capture experiment indicates that hydroxyl radical (⋅OH) and superoxide radical (⋅O2−) play a role in the photocatalytic degradation process. A Z‐type heterojunction may be formed on the 1T/2H‐MoS2/CdS composite based on a series of analyses, which improves the photocatalytic performance effectively via expanding the range of light response and promoting the separation of photogenerated electrons and holes. This work provides an alternative to constructing novel Z‐scheme photocatalysts with high performance in the absence of noble metals.

A flexible self-cleaning/antibacterial PVDF/T-ZnO fabric based on piezo-photocatalytic coupling effect for smart mask

A novel flexible composite fabric has been engineered by combining piezoelectric poly (vinylidene fluoride) (PVDF) and tetrapod zinc oxide (T-ZnO) nanostructures, which are integrated onto a nonwoven fabric substrate. This fabric exhibits a wide array of functionalities, notably self-cleaning and antibacterial properties, facilitated by the synergistic piezo-photocatalytic coupling effect. Through the utilization of the piezoelectric effect inherent in PVDF/T-ZnO in tandem with the photocatalytic attributes of T-ZnO nanostructures, the fabric achieves concurrent degradation of organic pollutants and antibacterial efficacy when exposed to mechanical vibration and solar irradiation. The piezo-photocatalytic coupling effect engenders an internal electric field that aids in the effective separation of photo-generated carriers (electrons and holes), thereby diminishing recombination rates and augmenting the efficiency of the photocatalytic degradation process. Notably, organic pollutants such as methylene blue and azithromycin exhibit degradation levels of 96.0% and 92.6%, respectively, within a timeframe of 25 and 60 min. The incorporation of PVDF/T-ZnO results in an approximate 40% enhancement in the degradation rate of organic substances compared to the use of T-ZnO in isolation. Furthermore, the composite fabric showcases exceptional antibacterial efficacy, effectively inhibiting the proliferation of Staphylococcus aureus. Experimental findings reveal that the average antibacterial zone diameter of the PVDF/T-ZnO fabric measures at 7.68 mm, significantly surpassing that of the T-ZnO fabric and nonwoven fabric. Given its remarkable self-cleaning and antibacterial attributes, the PVDF/T-ZnO fabric exhibits substantial potential for diverse applications, including the development of intelligent masks tailored for deployment in healthcare settings and polluted environments.

SYNTHESIS AND CHARACTERIZATION OF WO3/BiVO4/GRAPHENE TERNARY NANOCOMPOSITES FOR THE PHOTODEGRADATION OF METHLYENE BLUE AND TETRACYCLINE

In this study, a hydrothermal method was employed to synthesize the ternary nanocomposites comprising WO3/BiVO4/Graphene, all driven by visible light. The characteristics of these nanocomposites were interpreted through techniques such as UV-Vis, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and photoluminescence spectroscopy (PL). The enhanced performance of the composite, attributed to its heightened capability for separating charge carriers, outperformed that of the individual semiconductor components. The PL results validated the composite's improved charge separation. The nanocomposites have weaker PL peaks, indicating slower e-/h+ recombination. The balanced concentrations of the mixed semiconductors in the composite affected both PL intensity and photodegradation efficiency. The photocatalytic degradation of methylene blue (MB) and tetracycline (TC) was observed by nanocomposites. The heterogeneous nanocomposite WOBV/G-5 with 0.03mg graphene content has a better photocatalytic activity for both MB (63%) and TC (80%) than other concentrations. It has also been investigated using TOC and COD analysis. Moreover, zeta potential analysis and pH analysis have been done to check the conductivity of optimized photocatalyst. Additionally, to check the stability of WOBV/G-5 photocatalyst, recyclability test that shows 58% degradation rate after five cycles and analysis of XRD after recyclability have also been performed. Role of active species (h+, , and ) was observed by using different scavengers (EDTA, BQ, and IPA) in trapping experiment that plays a vital role in photocatalytic degradation process.

A new 2,5-bis(pyrid-4-yl)pyridine based Mn(II) metal–organic framework on photochemically antibiotic degradation

The synthesis of a new Mn(II)-based metal–organic framework (MOF), denoted as [Mn3(bpyp)3(HCOO)4(H2O)2·2NO3–·H2O]n(1) (bpyp = 2,5-bis(pyrid-4-yl)pyridine) was confirmed by single-crystal X-ray diffraction (XRD), UV–visible, Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). 1 exhibits a new 3D porous network with a (3,4,5)-connected topology. The photocatalytic degradation capability of 1 was investigated against various antibiotics, including dimethonidazole (DTZ), nitrofurazone (NFZ), nitrofurantoin (NFT), tinidazole (TDZ), and furazolidone (FZD). 1 exhibited exceptional photocatalytic activity against NFT, with a dosage of 5 mg/L resulting in a remarkable degradation efficiency of 96.81 % for 40 ppm NFT. Furthermore, a proposed photodegradation mechanism was investigated through radical trapping experiments, providing insights into the underlying pathways involved in the photocatalytic degradation process.

Constructing a CeFeO3/LaFeO3/ZnIn2S4 double Z-scheme heterojunction for photocatalytic atrazine degradation under visible light irradiation

The limited light absorption range and rapid recombination of interfacial charges were deemed to be the main restriction of the photocatalysts for atrazine (ATZ) degradation, and the construction of Z-scheme heterojunction was an effective strategy. Herein, a CeFeO3/LaFeO3/ZnIn2S4 (CFO/LFO/ZIS) double Z-scheme ternary heterojunction photocatalyst was fabricated by the in-situ precipitation and hydrothermal method. The photocatalytic ATZ degradation efficiency of optimized heterojunction reached 52% within 175min under visible light irradiation, which was 3.1, 3.7 and 1.7 times higher than that of CFO, LFO and ZIS, respectively. The enhanced photocatalytic activity was due to the excellent light capture capacity and improved photogenerated charge separation in CFO/LFO/ZIS double Z-scheme heterojunction photocatalyst. Meanwhile, some environmental factors on the influence of photocatalytic ATZ degradation performance were systematically investigated. Quenching experiments confirmed that ·OH, h+ and 1O2 were the main active species during the photocatalytic ATZ degradation process. The possible photogenerated charge separation route was proposed via the analysis of the IEF effects between CFO, LFO and ZIS. Finaly, the possible ATZ degradation pathway was deduced by LC-MS measurement and toxicity assessment of the intermediates were also evaluated by the Toxicity Estimation Software Tool (TEST). This work not only provided a potential magnetic recyclable ferrate based double Z-scheme heterojunction photocatalyst for enhancing photogenerated charge separation and light absorption, but also evaluated the intermediate toxicity and related environmental factors on the activity of photocatalyst, which was facilitating the practical application for the degradation of ATZ.

Facile fabrication of nanocellulose-supported membrane composited with modified carbon nitride and HKUST-1 for efficient photocatalytic degradation of formaldehyde

As a cellulose-derived material, nanocellulose possesses unique properties that make it an ideal substrate for various functional composite materials. In this study, we developed a novel composite membrane material capable of adsorbing and photo-catalyzing formaldehyde by immobilizing HKUST-1 (copper open framework composed of 1,3,5-benzenetricarboxylic acid) onto NFC (Nano-fibrillated cellulose) membranes and subsequently loading modified carbon nitride. The synthesized CNx@HN composite membrane (consisting of NFC membrane with anchored HKUST-1 and modified g-C3Nx nanosheets) was thoroughly characterized, and its photocatalytic degradation performance towards low concentrations of formaldehyde (3.0 mg/m3) was investigated. The results demonstrated that HKUST-1's porous nature exhibited a concentrated adsorption capacity for formaldehyde, while the modified CNx (Modified g-C3Nx nanosheets) displayed robust photocatalytic degradation of formaldehyde. The synergistic effect of HKUST-1 and modified CNx on the NFC membrane significantly enhanced the efficiency of formaldehyde degradation. Under xenon lamp irradiation, CNx@HN-5 achieved a total removal efficiency of 86.9 % for formaldehyde, with a photocatalytic degradation efficiency of 48.45 %, showcasing its exceptional ability in both adsorption and photocatalytic degradation of formaldehyde. Furthermore, after 10 cycles of recycling, the composite membrane exhibited excellent stability for the photocatalytic degradation process. Therefore, this study presents a green and facile strategy to fabricate nanocellulose-supported composite membranes with great potential for practical applications in formaldehyde degradation.

In-situ assembling novel N-Ti3C2/BiOClxBr1−x composites with enhanced photocatalytic degradation and nitrogen reduction activity

Herein, a collection of novel N-Ti3C2/BiOClxBr1−x composites are fabricated via a simple in-situ sonochemical process. Not only the preparation method for N-Ti3C2 but also the photocatalytic system of N-Ti3C2/BiOClxBr1−x are firstly developed. Multiple characterizations jointly demonstrate the successful fabrication of the composites. Compared to that of BiOClxBr1−x, the maximum improvements of 1.16, 1.25 and 1.26 folds are severally confirmed for the photocatalytic degradation of levofloxacin, Rhodamine B, and methylene blue over N-Ti3C2/BiOClxBr1−x composites. In addition, through radicals trapping tests, the primary active species in photocatalytic degradation process are verified to be O2−. Moreover, N-Ti3C2/BiOClxBr1−x composites also exhibit 1.18 and 1.14 times enhancements for NH3 production compared with that of BiOClxBr1−x with or without the presence of methanol, respectively. In addition, the maximum improvements of photo-current and photo-potential for BiOClxBr1−x are 1.29 and 1.86 folds with the introduction of N-Ti3C2, respectively. The enhanced photocatalytic activity of N-Ti3C2/BiOClxBr1−x composites is owing to the heightened light absorption, increased specific surface area, and accelerated separation of photoinduced carriers. Additionally, the stable photocatalytic properties of N-Ti3C2/BiOClxBr1−x are confirmed by three photocatalytic recycle tests on pollutant degradation and nitrogen reduction combined with X-ray diffraction patterns before and after three recycles. This study suggests that N-Ti3C2 is an efficient ornamentation for boosting photocatalytic activity ofBiOClxBr1−x, which can also be expanded as a promising modifier for other semiconductors.

Synthesis of magnetic NiFe2O4/rGO heterostructure as potential photocatalyst for a breakdown of malachite green (MG) dye under the visible source of light

The development of reactive radical generators, visible-light active photocatalysts with predictable stability, and efficient activity toward the breakdown of organic pollutant continue to be the primary goals of research in the area of photocatalytic environmental restoration. The present concern to on the development of an efficient heterostructure with a band gap operated on a visible region. The rGO incorporation into spinel material also decreases the agglomeration and provides a large surface area. The efficacy of NiFe2O4 (NF) nanoparticles, which are supported by rGO, as a photocatalyst for the breakdown of malachite green (MG) dye. The incorporation of rGO into NFO was investigated with the band gap property of the fabricated material using Tauc's plot profile. The NF/rGO nanocomposite underwent a reduction in magnetic properties determined through Vibrating Sample Magnetometer (VSM) analysis. However, the coercivity of the nanocomposite experienced a significant increase. When subjected to visible light, the degradation rate of malachite green (MG) dyes with NF/rGO was comparatively faster (93.84 %) than that of NF (64.33 %) and rGO (79.41 %). The cyclic photocatalytic degradation process exhibited notable reusability and stability of the magnetic recycling nanocomposite. The photocatalytic results revealed that the developed nanocomposite acts as a potential photocatalyst and it can also be employed in different applications.

Construction of BiOCl/bismuth-based halide perovskite heterojunctions derived from the metal-organic framework CAU-17 for effective photocatalytic degradation

The designed synthesis of an S-scheme heterojunction has possessed a great potential for improving photocatalytic wastewater treatment by demonstrating increased the photoredox capacity and improved the charge separation efficiency. Here, we introduce the fabrication of a heterojunction-based photocatalyst comprising bismuth oxychloride (BiOCl) and bismuth-based halide perovskite (BHP) nanosheets, derived from metal-organic frameworks (MOFs). Our composite photocatalyst is synthesized through a one-pot solvothermal strategy, where a halogenation process is applied to a bismuth-based metal-organic framework (CAU-17) as the precursor for bismuth sourcing. As a result, the rod-like structure of CAU-17 transforms into well-defined plate and nanosheet architectures after 4 and 8 h of solvothermal treatment, respectively. The modulation of the solvothermal reaction time facilitates the establishment of an S-scheme heterojunction, resulting in an increase in the photocatalytic degradation efficiency of rhodamine B (RhB) and sulfamethoxazole (SMX). The optimized BiOCl/BHP composite exhibits superior RhB and SMX degradation rates, achieving 99.8% degradation of RhB in 60 min and 75.1% degradation of SMX in 300 min. Also, the optimized BiOCl/BHP composite (CAU-17-st-8h sample) exhibited the highest rate constant (k = 3.48 × 10−3 min−1), nearly 6 times higher than that of the bare BHP in the photocatalytic degradation process of SMX. The enhanced photocatalytic efficiency can be endorsed to various factors: (i) the in-situ formation of two-components BiOCl/BHP photocatalyst, derived from CAU-17, effectively suppresses the aggregation of pristine BHP and BiOCl particles; (ii) the S-scheme heterostructure establishes a closely-knit interfacial connection, thereby facilitating efficient pathways for charge separation/transfer; and (iii) the BiOCl/BHP heterostructure enhances its capacity to absorb visible light. Our investigation establishes an effective strategy for constructing heterostructured photocatalysts, offering significant potential for application in photocatalytic wastewater treatment.

Multicolor lignin-derived carbon quantum dots: Controllable synthesis and photocatalytic applications

The cost-effective, high-performance fabrication of multicolor carbon quantum dots (CQDs) from biomass is critical to its prospective application. Lignin, with its phenylpropane structural unit and abundant functional groups, is a reliable precursor for the formation of high-quality CQDs. Here, CQDs from renewable lignin were successfully prepared via a two-step method, and controllable preparation of CQDs to emit blue, green, yellow, and red fluorescence was achieved by adjusting the N-containing acid dopant. The investigated fluorescence mechanism revealed that the energy bandgap of the lignin-derived CQDs decreased and the emission wavelength redshifted as the graphitization degree and number of C=O surface groups increased. The light absorption region of the Bi7O9I3 photocatalysts modified with blue CQDs to red CQDs gradually broadened in the redshifted direction. In particular, compared with pure Bi7O9I3 (70.9%), the red CQDs-modified Bi7O9I3 (RCQD/BOI) can remove 94.7% of antibiotics within 60 min of light irradiation. The superior photocatalytic activity of RCQD/BOI is attributed to the established internal electric field that accelerates charge transfer and effectively separates the photogenerated e+-h+ inside Bi7O9I3. Furthermore, through radical capture, electron paramagnetic resonance (EPR) experiments validated the photocatalytic mechanism of RCQD/BOI and revealed that h+, O2− and OH are key reactants in the photocatalytic degradation process. This promising and sustainable approach for the synthesis of multicolor lignin-derived CQDs opens the avenue of high-value utilization of biomass resources, green production of CQDs nanomaterials, and efficient development of CQDs-based photocatalysts for wastewater treatment.

Mitigation of caffeine micropollutants in wastewater through Ag-doped ZnO photocatalyst: mechanism and environmental impacts.

Micropollutants, such as caffeine (M-CF), pose a significant threat to ecosystems and human health through water and food sources. The utilization of metal oxide-based photocatalysts has proven to be an effective treatment method for the removal of organic pollutants. This study explores the efficacy of Ag-doped ZnO (Ag/ZnO) for removing M-CF from wastewater. The characterization of Ag/ZnO underscores the crucial role of band gap energy in the photocatalytic degradation process. This parameter influences the separation of electrons and holes (e-/h+) and the generation of reactive radicals. Under solar light, Ag/ZnO demonstrated markedly superior photocatalytic activity, achieving an impressive degradation efficiency of approximately 93.4%, in stark contrast to the 53.2% occurred by ZnO. Moreover, Ag/ZnO exhibited a remarkable degradation efficiency of M-CF in wastewater, reaching 83.5%. A key advantage of Ag/ZnO lies in its potential for recovery and reuse in subsequent treatments, contributing to a reduction in operational costs for industrial wastewater treatment. Impressively, even after five cycles, Ag/ZnO maintained a noteworthy photodegradation rate of M-CF at 78.6%. These results strongly suggest that Ag/ZnO presents a promising solution for the removal of micropollutants in wastewater, with potential scalability for industrial and large-scale applications.

Photocatalytic degradation process of antibiotic sulfamethoxazole by ZnO in aquatic systems: a dynamic kinetic model based on contributions of OH radical, oxygenated radical intermediates and dissolved oxygen

The photocatalytic degradation process of sulfamethoxazole (SMX) using ZnO in aquatic systems has been systematically studied by varying initial SMX concentration from 0 to 15 mgL−1 , ZnO dosage from 0 to 4 gL−1 and UV light intensity at the light source from 0 to 18 W(m-lamp length)−1 at natural pH. Almost complete degradations of SMX were achieved within 120 min for the initial SMX concentration ≤15 mgL−1 with ZnO dosage of 3 gL−1 and UV light intensity of 18 W(m-lamp length)−1. The photocatalytic degradation process was found to be interacted with the dissolved oxygen (DO) consumption. With oxygen supply through the gas-liquid free-surface, the DO concentration decreased significantly in the initial SMX degradation phase and increased asymptotically to the saturated DO concentration after achieving about 80% SMX degradation. The change in DO concentration was probably controlled by the oxygen consumption in the formation of oxygenated radical intermediates. A novel dynamic kinetic model based on the fundamental reactions of photocatalysis and the formation of oxygenated radical intermediates was developed. In the modeling the dynamic concentration profiles of OH radical and DO are considered. The dynamics of SMX degradation process by ZnO was simulated reasonably by the proposed model.

TiO2/CMWCNT/CaAlg composite membrane used for dye desalination and its rapid cleaning under ultraviolet light and advanced oxidation activated by monopersulfate

Membrane separation technology holds tremendous potential in treating dye wastewater. However, the widespread issue of membrane fouling leads to a significant decline in separation efficiency and lifespan. In this paper, titanium dioxide (TiO2)/carboxyl multi-walled carbon nanotube (CMWCNT)/calcium alginate (CaAlg) membranes were prepared by blending and simple cross-linking methods. The influence of TiO2 and CMWCNT concentrations on membrane performance, especially the anti-swelling performance, was explored. Additionally, the mechanical properties, filtration performance, fouling resistance, and dye/salt separation performance of the composite membrane were investigated. Notably, the rejection rate of dye molecules (Mw > 696 Da) was greater than 98 %, while the rejection rate of salt was less than 11.0 %. Furthermore, two methods for environmental-friendly cleaning membrane, photocatalytic degradation and advanced oxidation activated by monopersulfate, were performed. Finally, the photocatalytic degradation process and mechanism of Congo red (CR) were investigated by electron spin resonance (ESR).

BiOBr/Cu2S p-n heterojunction for efficient photodegradation of ciprofloxacin and tetracycline under visible light

With the increasing needs of people for a better life, the problem of water resources pollution has attracted wide attention. The construction of p-n heterojunction is an effective strategy to promote the removal of pollutants by photocatalysts. In this work, a series of BiOBr/Cu2S heterojunction photocatalysts with mass ratios of Cu2S have been synthesized successfully by a hydrothermal method combined with grinding method for photocatalytic degradation of tetracycline (TC) and ciprofloxacin (CIP). The results showed that BiOBr/Cu2S exhibited superior photodegradation efficiency of TC and ciprofloxacin CIP than BiOBr and Cu2S monomers. When the mass ratio of Cu2S is 0.15 %, the visible degradation of CIP and TC are 79.2 % in 90 min and 88.5% in 60 min. In addition, the effects of different inorganic ions and pH value on the photocatalytic performance of BiOBr/Cu2S were investigated. It was proved that superoxide free radical (•O2-) was the main active species by free radical trapping experiment. The photocatalytic degradation process was further evaluated by total organic carbon and mass spectrometry tests. This work provides a feasible construction strategy for photocatalysts with potential application in water resources pollutants.

Synthesis of PANI@Ce-doped ZnO (PCZ) heterojunction: A UV-Driven photocatalyst for reduction of Methylene Blue and study of their structural, optical and electrical properties

Abstract To address the significant issue of wastewater treatment, this research focused on synthesizing PANI@Ce-doped ZnO (PCZ), a ternary heterojunction with varying dopant concentrations. This heterojunction was prepared using an ultrasonic-assisted wet impregnation technique and underwent comprehensive analysis through several techniques, including XRD, UV-DRS, Photoluminescence, FE-SEM, EDAX, FTIR, and Impedance Analyzer. The synergy between the organic and inorganic frameworks resulted in an additive effect on the photocatalyst's degradation efficiency. This was achieved by enhancing its light-absorption properties and tuning the band gap energy. In the photocatalytic degradation process, reactive oxygen species (ROSs), including O2, OH, and h+, played a crucial role in breaking down MB (Methylene Blue) using the PANI@Ce-doped ZnO nanocomposites. Comparing PANI@Ce-doped ZnO with a 1% Cerium concentration (PCZ1) to its counterparts with different dopant concentrations, PCZ1 exhibited significantly elevated photocatalytic activity. This enhancement can be attributed to the improved transfer and separation of photogenerated charge carriers, which resulted from the effective formation of a heterojunction between the two components with a large trapping site.

Enhancing the Photocatalytic Degradation of Methylene Blue with Graphene Oxide-Encapsulated g-C3N4/ZnO Ternary Composites.

Methylene blue (MB) is a toxic contaminant present in wastewater. Here, we prepared various composites of graphene oxide (GO) with graphitic carbon nitride (g-C3N4) and zinc oxide (ZnO) for the degradation of MB. In comparison to ZnO (22.9%) and g-C3N4/ZnO (76.0%), the ternary composites of GO/g-C3N4/ZnO showed 90% photocatalytic degradation of MB under a light source after 60 min. The experimental setup and parameters were varied to examine the process and effectiveness of MB degradation. Based on the results of the experiments, a proposed photocatalytic degradation process that explains the roles of GO, ZnO, and g-C3N4 in improving the photocatalytic efficacy of newly prepared GO/g-C3N4/ZnO was explored. Notably, the g-C3N4/ZnO nanocomposite's surface was uniformly covered with ZnO nanorods. The images of the samples clearly demonstrated the porous nature of GO/g-C3N4/ZnO photocatalysts, and even after being mixed with GO, the g-C3N4/ZnO composite retained the layered structure of the original material. The catalyst's porous structure plausibly enhanced the degradation of the contaminants. The high-clarity production of g-C3N4 and the effectiveness of the synthesis protocol were later validated by the absence of any trace contamination in the energy-dispersive X-ray spectroscopy (EDS) results. The composition of the ZnO elements and their spectra were revealed by the EDS results of the prepared ZnO nanorods, g-C3N4/ZnO, and GO/g-C3N4/ZnO. The outcomes indicated that the nanocomposites were highly uncontaminated and contained all necessary elements to facilitate the transformative process. The results of this experiment could be applied at a large scale, thus proving the effectiveness of photocatalysts for the removal of dyes.

Methyl contributes to the directed phosphorus doping of g-C3N4: pH-dependent selective reactive oxygen species enable customized degradation of organic pollutants

In the photocatalytic degradation process, constructing a controllable composite oxidation system with radicals and nonradicals to meet the requirement for efficient and selective degradation of diverse pollutants is significant. Herein, a methylated and phosphorus-doped g-C3N4 (NPEA) can exhibit selective radical and nonradical species formation depending on the pH values. The NPEA can spontaneously switch the production of active species according to the pH value of the reaction system, exhibiting steady-state concentrations of ·O2− for 11.83 × 10−2 µmol L−1 s−1 (with 92.7 % selectivity) under alkaline conditions (pH = 11), and steady-state concentrations of 1O2 for 5.18 × 10−2 µmol L−1 s−1 (with 88.7 % selectivity) under acidic conditions (pH = 3). The NPEA exhibits stability and universality in the degradation of pollutants with rate constant for sulfamethazine (k = 0.261 min−1) and atrazine (k = 0.222 min−1). Moreover, the LC-MS and Fukui function demonstrated that the NPEA can tailor degradation pathways for pollutants, achieving selective degradation. This study offers a comprehensive insight into the mechanism of the photocatalytic oxidation system, elucidating the intricate interplay between pollutants and reactive oxygen species.

Ultrasonic-assisted synthesis of CaCu3Ti4O12/reduced graphene oxide composites for enhanced photocatalytic degradation of pharmaceutical products: Ibuprofen and Ciprofloxacin.

The objective of this research is to create a highly effective approach for eliminating pollutants from the environment through the process of photocatalytic degradation. The study centers around the production of composites consisting of CaCu3Ti4O12 (CCTO) and reduced graphene oxide (rGO) using an ultrasonic-assisted method, with a focus on their capacity to degrade ibuprofen (IBF) and ciprofloxacin (CIP) via photodegradation. The impact of rGO on the structure, morphology, and optical properties of CCTO was inspected using XRD, FTIR, Raman, FESEM, XPS, BET, and UV-Vis. Morphology characterization showed that rGO particles were dispersed within the CCTO matrix without any specific chemical interaction between CCTO and C in the rGO. The BET analysis revealed that with increasing the amount of rGO in the composite, the specific surface area significantly increased compared to the CCTO standalone. Besides, increasing rGO resulted in a reduction in the optical bandgap energy to around 2.09 eV, makes it highly promising photocatalyst for environmental applications. The photodegradation of IBF and CIP was monitored using visible light irradiation. The results revealed that both components were degraded above 97% after 60 min. The photocatalyst showed an excellent reusability performance with a slight decrease after five runs to 93% photodegradation efficiency.