Photocatalytic Degradation Efficiency Research Articles

Lead-Free Cs2AgBiBr6/TiO2 S-Scheme Heterojunction for Efficient Photocatalytic Antibiotic Rifampicin Degradation.

Exploring efficient and stable halide perovskite-based photocatalysts is a great challenge due to the balance between the photocatalytic performance, toxicity, and intrinsic chemical instability of the materials. Here, the environmentally friendly lead-free perovskite Cs2AgBiBr6 confined in the mesoporous TiO2 crystal matrix has been designed to enhance the charge carrier extraction and utilization for efficient photocatalytic rifampicin degradation. The as-prepared Cs2AgBiBr6/TiO2 catalyst was stable in air for over 500 days. An S-scheme heterojunction was formed between the (004) plane of Cs2AgBiBr6 and the (101) plane of TiO2 through the Bi-O-Br bonds. The built-in electric field at the interface efficiently promoted the photoinduced charge separation and carrier extraction. The Cs2AgBiBr6/TiO2-200 showed a 92.83% degradation efficiency of rifampicin within 80 min under simulated sunlight illumination (AM 1.5G 100 mW cm-2). This work offers an effective way for the construction of halide perovskite-based photocatalysts with high photocatalytic performance, good stability, and low toxicity simultaneously.

Exploring the formation of S-scheme heterojunctions in CuFe2O4/Bi2MoO6 porous cubes for photocatalytic removal of tetracycline

Exploring highly active and noble metal-free photocatalysts for the efficient photocatalytic degradation of antibiotics is of great significance. The CuFe2O4 nanostructured cube is synthesized by using a self-sacrificial template strategy, and two-dimensional Bi2MoO6 nanosheets are grown on the surface of CuFe2O4 through a solvothermal method to construct CuFe2O4/Bi2MoO6 S-scheme heterostructure. The CuFe2O4/Bi2MoO6 composite material exhibits eminent photocatalytic activity for the degradation of TC under simulated sunlight, with the optimal ratio CFO/BMO-2 achieving a degradation rate of 98.54 % within 30 min (initial concentration of TC: 50 mg L−1). In addition, CFO/BMO-2 also has excellent magnetic recyclability and cycling ability. Rice cultivation tests demonstrate that the biotoxicity of TC is effectively removed. Density functional theory calculations and in-situ irradiated X-ray spectroscopy deeply reveal the mechanisms of charge separation and transfer of S-scheme heterojunctions in CuFe2O4/Bi2MoO6. The construction of S-scheme heterojunctions promotes the separation of photo-induced charge carriers and improves photocatalytic degradation performance by retaining holes and electrons with strong redox ability. The work provides a practicable method for constructing efficient spinel photocatalysts to drive wastewater treatment reactions, and the constructed magnetically recyclable photocatalysts have certain practical application potential.

Investigation of fullerene and non-fullerene materials in organic photocatalysts on the efficiency of photocatalytic degradation of polychlorinated biphenyls

The photocatalytic degradation of polychlorinated biphenyls (PCBs) is advancing, yet the efficiency of degradation within the visible spectral range continues to encounter significant challenges. In this study, two biochar-based organic semiconductor photocatalysts, Active Carbon@PTQ10 (5,8-Dibromo-6,7-difluoro-2-(2-hexyldecoxy)quinoxaline; trimethyl-(5-trimethylstannylthiophen-2-yl)stannane): ITIC-Th (Propanedinitrile,2,2′-[[6,6,12,12-tetrakis(5-hexyl-2-thienyl)-6,12-dihydrodithieno[2,3-d: 2′,3′-d’] −s-indaceno[1,2-b:5,6-b’] dithiophene-2,8-diyl] bis[methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)]] bis-) (AC@PI) and Active Carbon@PTQ10: PC71BM (6,6)-phenyl C71 butyric acid methyl ester), were synthesized using a wide bandgap material, PTQ10, as the electron donor, along with a non-fullerene material, ITIC-Th, and a fullerene material, PC71BM, as the acceptors, respectively. Under optimized conditions, AC@PI degraded 93.4 % of 2,2 ’,4,4 ’-tetrachlorobiphenyl (PCB 47) within 60 min. By incorporating a non-fullerene acceptor (ITIC-Th), AC@PI exhibits a larger surface photopressure, a lower hole-electron transfer ratio, a broader absorption spectrum (400 – 1000 nm), and enhanced structural stability. AC@PI can generate photogenerated electrons and holes, as well as superoxide anions (O2−) and hydroxyl radicals (OH), through type II heterojunctions, which contributes to its exceptional properties. This study synthesized novel organic semiconductor catalysts that offer a green, efficient, and non-toxic method for the degradation of aromatic pollutants, such as polychlorinated biphenyls.

Efficient photocatalytic degradation of ciprofloxacin using floating α-NiMoO4/mpg-C3N4/EP under visible light

Conventional water treatment processes often fail to effectively remove antibacterial drugs, necessitating advanced strategies. This study presents the synthesis of novel floating, visible light-active α-NiMoO4/mpg-C3N4/EP composites for the removal of ciprofloxacin (CFX), a widely used quinolone antibiotic, from water. These composites are easily recoverable, highly stable, and demonstrate excellent reusability. The optimal photocatalyst, NC-101/EP (α-NiMoO4/mpg-C3N4 = 10:1), achieved 96.2 ± 1.1% degradation of CFX at 1.6 g L−1 within 80 min under visible light, significantly outperforming previous benchmarks. This high efficiency is attributed to the formation of interfacial junctions and a built-in electric field, which enhanced charge transfer and hydroxyl radical generation through an S-scheme mechanism. Fluorescence spectroscopy provided precise monitoring of CFX degradation without interference from coexisting intermediates. Density functional theory (DFT) calculations revealed that hydroxyl radicals initiated highly favorable and spontaneous oxidation of CFX, with a reaction rate constant of 6.04 × 109 M−1 s−1. The preferred oxidation pathway followed the sequence: HO-addition > H-abstraction > single electron transfer. Four degradation pathways were identified, with key intermediates confirmed by high-resolution mass spectrometry. The process also significantly reduced CFX toxicity, ensuring minimal environmental impact. These findings position NC-101/EP as a promising photocatalyst for large-scale water treatment applications targeting antibiotic contamination.

Photocatalytic NOx degradation and [formula omitted] adsorption by mortar modified with S-g-C3N4/MgAl-CLDH: Influence factors and stability

NOx is a harmful gas that causes respiratory diseases and acid rain. Commonly used photocatalysts for degrading NOx such as UV responsive TiO2 show weak photocatalytic degradation efficiency under visible light. Furthermore, the great concern is that the degradation product, nitrates (NO3-), from NOx could be washed away and increase the nitrogen deposition and eutrophication in the surrounding soil and aquatic environments, resulting in serious secondary pollution. To address these issues, this study proposes a novel solution by incorporating S-g-C3N4/MgAl-CLDH nanocomposites into a cementitious system which features high NOx degradation efficiency under visible light condition and the efficient capture and adsorption of NO3- in situ. The NOx degradation was comprehensively studied, encompassing the influencing factors and stability. The mechanism for NO3- adsorption process was expounded using the isothermal model. The results show that the amount of exposed S-g-C3N4/MgAl-CLDH and the contact area between S-g-C3N4/MgAl-CLDH and NOx are the essential reasons affecting the NOx degradation. The NOx degradation ability of photocatalytic mortar exhibits excellent stability with the NOx removal ratio decreasing by only 4.8 % and 14.5 % after ten consecutive tests and 120 min of ultrasonic washing, respectively. Furthermore, S-g-C3N4/MgAl-CLDH increases the NO3- adsorption capacity of photocatalytic mortar by about 1.5 times, and the adsorption process of NO3- follows the Freundlich isotherm. The study offers an alternate method for designing innovative nanocomposites in cement-based materials to control environmental pollution.

Investigation of the Effect of Oxide Additives on the Band Gap and Photocatalytic Efficiency of TiO2 as a Fixed Film.

The effects of various additives (Y2O3, Ga2O3, and WO3) on photocatalytic degradation efficiency under UV light-emitting diodes (LEDs) and the optical properties of TiO2 Degussa P25 were investigated using ketoprofen and diclofenac, two non-steroidal anti-inflammatory drugs commonly detected in German rivers. Experimental results demonstrated that thin films containing these additives exhibited similar photocatalytic degradation efficiencies as pure TiO2, achieving a 30% degradation of ketoprofen over 150 min. In contrast, the Y2O3/TiO2 thin film showed significantly improved performance, achieving a 46% degradation of ketoprofen in 180 min. Notably, the Y2O3/TiO2 system was three times more effective in degrading diclofenac compared to pure TiO2. Additionally, the Y2O3/TiO2 photocatalyst retained its activity over three successive cycles with only a slight decrease in efficiency. The photocatalytic degradation of both organic pollutants followed first-order kinetics with all photocatalysts. The investigation included SEM imaging to assess the surface homogeneity of the thin films and UV-vis solid-state spectroscopy to evaluate the impact of the additives on the energy band gap of TiO2.

Study of Fe3O4 and Cu2+ doped modified Fe3O4 nano catalyst for photocatalytic degradation of methylene blue and eriochrome black-T dyes: Synthesis, characterization, and antimicrobial assessment

This study presents the synthesis and characterization of undoped Fe3O4 and 3% Cu-doped Fe3O4 nanoparticles via a cost-effective and environmentally friendly co-precipitation method. A comprehensive suite of nanomaterial characterization techniques, including energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS), was employed to confirm the elemental composition, structural parameters, and chemical states of the prepared materials. Additionally, fragmentation analysis using LC–MS illustrated the structural stability and breakdown of the nanoparticles under specific conditions. Both the materials were characterized by vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller (BET) for investigating the magnetic, and surface characteristics respectively. Furthermore, the synthesized nanoparticles were evaluated for their photocatalytic degradation efficiency towards methylene blue and eriochrome black T dyes. A systematic investigation of various parameters, including the pH of the dye solution, dye concentration over time, catalyst dose, dye concentration versus degradation, catalyst reusability, and kinetic study, was conducted to understand the factors influencing the photocatalytic activity of both undoped and Cu-doped Fe3O4 nanoparticles. The LC-MS analysis predicted the probable degradation pathways of MB and EBT dyes. This work provides insights into the sustainable synthesis, comprehensive characterization, and practical application of Fe3O4-based nanoparticles for water treatment applications, highlighting their potential as efficient and environmentally benign Photocatalyst for wastewater remediation. An investigation was conducted to investigate the antimicrobial properties of both undoped and doped nanoparticles. The minimum inhibitory concentration (MIC) of the synthesized nanoparticles were determined against the bacterial strains E. coli, P. aeruginosa, S. aureus, and S. pyogenes, as well as the fungal strains C. albicans, A. niger, and A. clavatus.

Surface plasmon effect combined with S-scheme charge migration in flower-like Ag/Ag6Si2O7/Bi12O17Cl2 enables efficient photocatalytic antibiotic degradation

Developing robust photocatalysts for photocatalytic environment decontamination is significant and challenging. A novel flower-like S-scheme Ag/Ag6Si2O7/Bi12O17Cl2 (AASO/BOC) plasmonic heterojunction is successfully constructed using a facile route, and applied in photocatalytic destruction of tetracycline hydrochloride (TC) and levofloxacin (LEV) under visible-light irradiation. Benefiting from the combination of S-scheme Bi12O17Cl2/Ag6Si2O7 heterojunction and the plasma Ag, the production and separation of photogenerated carriers are dramatically enhanced. Consequently, compared to the pristine Bi12O17Cl2 and Ag6Si2O7, AASO/BOC displays superior photocatalytic degradation performance. Impressively, the photocatalytic TC degradation rate of AASO/BOC-2 reaches 0.0260 min−1, which is approximately 3.1, 14.4 and 2.0 times those of Bi12O17Cl2, Ag6Si2O7 and Bi12O17Cl2/Ag6Si2O7, respectively. Moreover, the photocatalytic mechanism of TC degradation is studied in depth via various techniques, and the photogenerated OH, O2− and h+ collectively contribute to the photo-degradation of TC. This research puts forward a neoteric approach to designing plasmonic S-scheme photocatalysts for environmental applications.

Captivating 2H-MoS2 nanoflowers for efficient NH3 detection and photocatalytic dye degradation

This research unveils the gas sensing and photocatalytic potential of 2H-MoS2 nanoflowers, offering a promising solution for ammonia sensing and wastewater remediation. The 2H phase of MoS2 nanoflowers is synthesized via a simple one-step hydrothermal method using ammonium heptamolybdate and thiourea. The elemental and morphological study confirms the formation of the 2H phase of MoS2 nanoflowers with an average sheet thickness of 14 nm. The XRD and HR-TEM analysis findings are in good accordance with the interlayer spacing of MoS2, calculated to be 0.64 nm. The 2H-MoS2 nanomaterial based chemiresistive sensor is tested for six different targets (NH3, C2H5OH, C3H6O, C3H7OH, HCHO, and C6H5CH3) and shows good selectivity towards ammonia (NH3) with the highest response of 81 %. The response-recovery time, repeatability, concentration, and humidity-based analysis are conducted for the analysis of the sensor. The fabricated 2H-MoS2 based sensor shows a response time of 8.5 s and a recovery time of 4.3 s. Furthermore, three model water contaminated dyes, MB, MO, and RB, are chosen for the photocatalytic experiment under visible light irradiation. The reusability, relative degradation, and pseudo-first-order analysis are used to evaluate the photocatalytic dye degradation properties of 2H-MoS2 nanoflowers. The reaction rate constant of 2H-MoS2 nanomaterials for MB, MO, and RB dyes is calculated to be (0.05010) min−1, (0.03458) min−1, and (0.02516) min−1, respectively. The maximum degradation efficiency of 2H-MoS2 nanoflowers towards MB, MO, and RB dye is 95 %, 86 %, and 76 %, respectively, under visible light irradiation. These findings suggest that the hydrothermally synthesized 2H-MoS2 nanoflowers have multifunctional applications such as effective NH3 sensors as well as photocatalysts for organic dye degradation, paving the way for more efficient and sustainable gas sensing and wastewater treatment technologies.

Tartrate‐Anchored Tetranuclear Titanium‐Oxo Clusters Functionalized by Chromophore Ligands Exhibiting Photoelectric Response and Photodegradation Performances of Methylene Blue

ABSTRACTIn recent years, researchers have devoted considerable effort to the study of high crystalline titanium‐oxo clusters (TOCs), because TOCs are considered to be the molecular analogs of TiO2 nanoparticles and have the potential to be utilized as effective cleaning and catalytic materials. Two new tartrate‐anchored tetranuclear TOCs functionalized with chromophore ligand of p‐nitrobenzoate (NB)/p‐toluenesulfonate (TS), namely, [Ti4(TA)(NB)2(OiPr)10] (1, H4TA = tartaric acid) and [Ti4(TA)(TS)2(OiPr)10] (2), were synthesized and their structures were characterized by various methods. The molecular structure analyses indicated that 1 and 2 are all tetranuclear {Ti4} TOCs, in which tartrate appears as a hexadentate μ4‐bridging ligand while p‐nitrobenzoate/p‐toluenesulfonate acts as a bidentate μ2‐bridging ligand. TOCs 1 and 2 are of good thermal and solvent stability. Furthermore, their photocurrent responses and photocatalytic degradation activities towards methylene blue (MB) were also investigated. In the presence of H2O2, the photocatalytic degradation efficiencies of MB by 1 and 2 are about 84.43% and 71.00%, respectively, at room temperature under visible light irradiation for 60 min. These findings shed light on designing efficient polycarboxylate‐based TOCs photocatalysts.

An efficient, green, and magnetic recycling wastewater treatment technique enabled by ZnO/NiFe2O4/BiOBr 3D nanofibers photo-fenton process

A novel magnetic recycling ZnO/NiFe2O4/BiOBr 3D nanofibers photo-Fenton system was successfully prepared by parallel electrospinning combining with solvothermal method. ZnO/NiFe2O4 composite nanofibers was prepared via parallel electrospinning, then ZnO/NiFe2O4/BiOBr 3D nanofibers was obtained by solvothermal growth of BiOBr on electrospun ZnO/NiFe2O4 composite nanofibers. The composition, morphologies, structures and photocatalytic properties of ZnO/NiFe2O4/BiOBr 3D nanofibers were systematically tested and analyzed, and some meaningful results were obtained. The prepared ZnO/NiFe2O4/BiOBr 3D nanofibers, combined with H2O2, form a photo-Fenton system that exhibits excellent photocatalytic performance. When 0.05 mL of H2O2 is added to the photo-Fenton system, the degradation rate of organic dye Rhodamine B (RhB) reaches 99.61 % under light exposure for 10 min. Capture experiments and Electron Spin Resonance (ESR) measurements have confirmed that holes (h+) and hydroxyl radicals (·OH) are the primary active species that play a dominant role in the photocatalytic degradation of Rhodamine B (RhB). Furthermore, the ZnO/NiFe2O4/BiOBr 3D nanofibers have demonstrated exceptional photocatalytic degradation efficiency towards RhB, maintaining a degradation rate of over 95 % even after undergoing three recycling experiments. Significantly, this photo-Fenton system also has good magnetic properties, which can be separated from the treatment system under the applied magnetic field, avoiding secondary pollution of the treatment system, improving reuse rate and saving costs. This study provides valuable insights for the purposeful utilization of the photocatalytic materils.

Rapid synthesis of novel S-scheme CaBi6O10/Bi2WO6 heterojunction film for efficient p-chlorophenol photocatalytic degradation

Efficient photocatalysts played a crucial role for degrading phenol pollutants in wastewater and vital for environmental remediation. In this study, a series of novel CaBi6O10/Bi2WO6 (CBO/BWO) step-scheme (S-scheme) heterojunction films were synthesized on the glass substrates through a facile and rapid spraying-calcination method. The CBO/BWO film demonstrated superior visible-light-driven catalytic activity for p-chlorophenol (4-CP) degradation within the fixed-bed photoreactor setup, compared with those of the single-component samples. Typically, the optimal 40CBO/BWO catalyst achieved 4-CP degradation efficiency of approximately 89.5 % after only 60 min under light exposure, attributed to the enhanced visible-light-absorption property and effective charge separation within the S-scheme heterojunction while maintaining high redox abilities among photoinduced carriers. Furthermore, the CBO/BWO catalyst displayed robust resistance to various metal cationic additives. Multiple key intermediates, such as phenol, dihydroxybenzene, benzoquinone and maleic acid, were identified in catalyzing process of 4-CP decomposition via oxidation processes involving hydroxyl radicals and superoxide radical as the primary active species. The above feasible photodegradation mechanism was elucidated and proven. Hence, this work offers valuable insights into developing efficient heterostructure photocatalysts for practical application of environmental remediation.

Intrinsically microporous polyimide-based metal-free catalysts for round-the-clock photodegradation of organic pollutants

Photocatalytic degradation of organic pollutants is an essential technology for various environmental applications. However, the effectiveness of most photocatalysts is restricted to light. Herein, we report metal-free catalysts derived from intrinsically microporous polyimide for persistence in photocatalytic degradation of dyes. We systematically investigate the effect of porosity and functionality on photocatalytic efficiency. Both the pristine 4,4′-(hexafluoroisopropylidene)diphthalic anhydride-3,3′-dimethylnaphthidine and its thermally annealed counterpart at 530 °C exhibit high charge storage capabilities, enabling continuous photodegradation in the absence of light. The pre-irradiated catalyst exhibits an approximately 99% degradation of the dye, with a ~40% improvement relative to the non-pre-irradiated sample. We studied the influence of the chemical structure and porosity on the photocatalytic degradation efficiency in darkness by varying the polyimide chemical structure using different diamines. This research underscores the potential of polymers with intrinsic microporosity for application in the continuous degradation of dyes, contributing to the pursuit of cleaner water.

The one-pot synthesis of defect-rich bimetallic MOFs for efficient photocatalytic Fenton degradation of organic pollutants

The efficient and straightforward treatment of organic contaminants in water remains a significant challenge. This study presents the synthesis of a defective NH2-MIL-88Fex/Cuy photo-Fenton catalyst via a simple one-pot hydrothermal method. The incorporation of the inexpensive metal Cu enhances the valence cycles of Cu2+/Cu+ and Fe3+/Fe2+ under the photo-Fenton system, thereby compensating for the rapid consumption rate of ·OH radicals. Degradation tests demonstrated that NH2-MIL-88Fe0.5/Cu0.5 can degrade 99.99 % of methylene blue within 30 min under visible light irradiation. Free radical trapping experiments and Electron Paramagnetic Resonance (EPR) confirmed that ·OH radicals play a predominant role in the catalytic system. Density Functional Theory (DFT) calculations verified the improved binding energy of the catalyst materials following the introduction of structural defects. The degradation pathway and mechanism of methylene blue were elucidated. This study offers a novel approach for designing photo-Fenton catalysts and holds significant promise for practical applications in wastewater treatment.

Application of Ce2(WO4)3–ZnO–CuO nanocomposite as active photocatalyst for removal of ciprofloxacin from wastewater

In this study, the synthesis of Ce2(WO4)3/ZnO/CuO nanocomposite (NCs) was carried out using Co-precipitation method. The structural, morphological and spectral confirmation was achieved through X-ray diffraction (XRD), Scanning electron microscopy (SEM), Differential reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR) analysis. The degradation efficiency for photocatalytic degradation of Ciprofloxacin (CF) and band gap value of prepared Ce2(WO4)3/ZnO/CuO nanocomposite was determined by using UV–Visible and DRS analysis. Band gap value for Ce2(WO4)3/ZnO/CuO was found to be 1.39 eV. Effects of different parameters such as contact time, pH, and effect of concentration of catalyst were investigated to optimize degradation conditions. This prepared nanocomposite was used for the degradation of CF and about 91 % degradation efficiency of CF has been achieved at pH 5 within 70 min by irradiation under sunlight and 60 mg concentration of photocatalyst. The EDTA and IPA scavenged photo-generated holes and hydroxyl ions respectively, the decrease in photocatalytic degradation indicates that holes and hydroxyl ions are reactive species in photocatalytic degradation of CF. The value of R2 = 0.99 confirms the validity of Pseudo first order and Langmuir-Hinshelwood kinetic model for the degradation of CF. These results showed a novel method for the preparation of nanocomposite and the efficient degradation of antibiotics and can be applied to industrial manufacture.

Built-in electric field mediated S-scheme high-quality charge separation in BiVO4/NiAl-LDH heterojunction for highly efficient photocatalytic degradation of antibiotics

As an up and coming technology for antibiotics removal from water, photocatalysis required well-pleasing charge isolation, migration, and utilization efficiency to come true an efficaciously photocatalytic performance, but developing affordable and high-efficiency photocatalyst remains a great challenging. Herein, an emerging S-scheme BiVO4/NiAl-LDH heterojunction was ingeniously fabricated by mulberry-like BiVO4 microrods immobilized onto the surfaces of flower-like NiAl-LDH microspheres. The physicochemical properties of the BiVO4/NiAl-LDH heterojunctions were analyzed by multiple techniques. Expectedly, the manufactured BiVO4/NiAl-LDH heterojunction endowed a significantly strengthened removal rate of tetracycline compared to mono-component BiVO4 and NiAl-LDH under visible light. Specifically, the optimized BVO-NAL-3 manifested the exceptional tetracycline removal efficiency with an apparent rate constant of up to 0.0409 min−1, which was close to 34.1 and 4.4 times more rapid than those of neat NiAl-LDH and BiVO4, severally. This signal enhancement was centrally related to the creation of S-scheme heterojunction, which accelerated high-quality charge separation and strengthened redox capacity under the force of created a built-in electric field, which was corroborated by experiments results together with density functional theory calculations. Besides, the generation of superoxide radicals and photogenerated holes played an imperative role in the tetracycline degradation over BVO-NAL-3. Noteworthily, BVO-NAL-3 expressed the satisfactory stability and exceptional resistance to environmental interferences. More amazingly, other refractory antibiotics including ciprofloxacin, levofloxacin and amoxicillin were also efficaciously eliminated by BVO-NAL-3. Ultimately, the possible degradation mechanism and pathways of tetracycline were logically inferred. This work unveils a valuable afflatus for the reasonable layout and establishment of S-scheme heterojunction with high-quality charge separation for the eradication of antibiotics.

Novel synthesis organic–inorganic heterojunctions of protonated g-C3N4/Fe3O4/AgBr/AgCl/AgI quinary magnetic photocatalyst with enhanced visible-light photocatalytic degradation of methylene blue in water

A novel magnetic quinary nanocomposite, protonated g-C3N4/Fe3O4/AgBr/AgCl/AgI, was synthesized using a wet chemical method. The multi-heterojunction photocatalyst with multi-carrier source and multi-channel carrier transport is constructed to enhance the photocatalytic degradation performance of pure g-C3N4. The design of the quinary nanocomposite is also an effective approach to solve the chemical stability problem of silver halides. The photocatalytic degradation efficiency under visible light irradiation was analyzed for methylene blue (MB) as the target organic pollutant. The quinary nanocomposite with 10 % g-C3N4 displayed high photocatalytic performance, with 83 % of MB degraded under 6 h LED white light irradiation. The effective quinary nanocomposite has good magnetic properties and can be magnetically separated to prevent secondary pollution of the photocatalyst in water. Parameters such as initial concentration of pollutant, initial solution pH, and light source were studied. Zeta potential results showed that the quinary nanocomposite could disperse homogenously to decrease aggregation in the solution. The photocatalytic degradation mechanism was investigated, and the mineralization results were analyzed based on liquid chromatography-mass spectroscopy (LC-MS) and total organic carbon (TOC). It was found that the hydroxyl and superoxide radicals were major reactive species by scavenging experiments. Additionally, protonated g-C3N4/Fe3O4/AgBr/AgCl/AgI nanocomposite showed excellent reusability after magnetic separation and regeneration, thus suggesting it to be a promising photocatalyst for treating wastewater containing organic contaminants.

Preparation and Photocatalytic Properties of Al2O3-SiO2-TiO2 Porous Composite Semiconductor Ceramics.

Titanium dioxide (TiO2) is widely employed in the catalytic degradation of wastewater, owing to its robust stability, superior photocatalytic efficiency, and cost-effectiveness. Nonetheless, isolating the fine particulate photocatalysts from the solution post-reaction poses a significant challenge in practical photocatalytic processes. Furthermore, these particles have a tendency to agglomerate into larger clusters, which diminishes their stability. To address this issue, the present study has developed Al2O3-SiO2-TiO2 composite semiconductor porous ceramics and has systematically explored the influence of Al2O3 and SiO2 on the structure and properties of TiO2 porous ceramics. The findings reveal that the incorporation of Al2O3 augments the open porosity of the ceramics and inhibits the aggregation of TiO2, thereby increasing the catalytic site and improving the light absorption capacity. On the other hand, the addition of SiO2 enhances the bending strength of the ceramics and inhibits the conversion of anatase to rutile, thereby further enhancing its photocatalytic activity. Consequently, at an optimal composition of 55 wt.% Al2O3, 40 wt.% TiO2, and 5 wt.% SiO2, the resulting porous ceramics exhibit a methylene blue removal rate of 91.50%, and even after undergoing five cycles of testing, their catalytic efficiency remains approximately 83.82%. These outcomes underscore the exceptional photocatalytic degradation efficiency, recyclability, and reusability of the Al2O3-SiO2-TiO2 porous ceramics, suggesting their substantial potential for application in the treatment of dye wastewater, especially for the removal of methylene blue.

Influence of gadolinium substitution on the crystal structure of NiO and its maximized photocatalytic degradation activity on tetracycline and direct yellow pollutants

Gadolinium-substituted NiO crystal structures with excellent stability were utilized for the first time to degrade antibiotic and organic dye pollutants. A simple hydrothermal technique was used to synthesize different concentrations of Gd3+ substituted NiO, and the catalysts were thoroughly characterized using sophisticated techniques to explore the influence of Gd3+ on the crystal structure and optical characteristics of NiO. The 1.5% Gd3+ substituted NiO showed outstanding photocatalytic activity on tetracycline and direct yellow degradation, with percentages of 90.72 and 95.5%, respectively. The improvement of photocatalytic degradation efficiency is primarily due to the suppression of photoinduced electron and hole recombination via the creation of Gd3+ as the inner energy band state below the conduction band. The recycling experiments revealed that the catalyst is more stable, with no indication of loss after ten cycles. Scavenging investigations also demonstrated that superoxide and holes were responsible for the efficient degradation of pollutants.

Nano-CeO2 for the Photocatalytic Degradation of the Complexing Agent Citric Acid in Cu Chemical Mechanical Polishing

Cu interconnect chemical mechanical polishing (CMP) technology has been continuously evolving, leading to increasingly stringent post-CMP cleaning requirements. To address the environmental pollution caused by traditional post-CMP cleaning solutions, we have explored the use of photocatalytic processes to remove citric acid, which is a commonly used complexing agent for CMP. In this study, CeO2 abrasives, characterized by a hardness of 5.5, are extensively employed in CMP. Importantly, CeO2 also exhibits a suitable band structure with a band gap of 2.27 eV, enabling it to photocatalytically remove citric acid, a commonly used complexing agent in Cu CMP. Additionally, the integration of H2O2, an essential oxidant in Cu CMP, enhances the photocatalytic degradation efficiency. The research indicates that the removal rate of single-phase CeO2 was 1.78 mmol/g/h and the degradation efficiency increased by 40% with the addition of H2O2, attributed to the hydroxyl radicals generated from a Fenton-like reaction between H2O2 and CeO2. These findings highlight the potential of photocatalytic processes to improve organic contaminant removal in post-CMP cleaning, offering a more sustainable alternative to conventional practices.