Photocatalytic Activity Of Nanocomposites Research Articles

Sustainable scalable solid-state synthesis of highly efficient synergetic 2D/0D micro/nanostructured g-C3N4/CdS photocatalysts for hydrogen production and water purification

Highly efficient synergetic photocatalysts based on graphitic carbon nitride (g-C3N4) and cadmium sulfide (CdS) semiconductors with 2D/0D micro/nanostructure were successfully prepared by easy scalable mechanochemical method and investigated. An in-depth study of electrons' binding energy of semiconductors and their influence on the photocatalytic activity of nanocomposites has been performed. The synthesized materials were applied for the photodegradation of Orange II dye and photocatalytic hydrogen evolution. The obtained experimental results revealed that nanocomposite with 20 wt% of g-C3N4 and 80 wt% of CdS is able to completely decompose Orange II molecules after two hours of visible light irradiation. The mechanism and pathways of photocatalytic reactions have been proposed. The nanocomposite composed of 60 wt% g-C3N4 and 40 wt% CdS, decorated by a platinum (Pt) co-catalyst, demonstrated the peak hydrogen evolution rate (HER) of 2254.54 μmolh−1 g−1 after 4th hour of solar light illumination. This remarkable achievement, with an apparent quantum efficiency (AQE) of 2.0%, occurred on the fourth hour of solar light irradiation. Furthermore, under continuous visible light irradiation, the sample with the same composition is capable of producing hydrogen. The peak HER rate recorded was 246.14 μmolh−1 g−1 (AQE = 0.44%) after 2.5 h, and this remained consistently the same throughout the entire duration of the process.

Achieving Highly Efficient Photocatalytic Hydrogen Evolution through the Construction of g-C3N4@PdS@Pt Nanocomposites.

Selective supported catalysts have emerged as a promising approach to enhance carrier separation, particularly in the realm of photocatalytic hydrogen production. Herein, a pioneering exploration involves the loading of PdS and Pt catalyst onto g-C3N4 nanosheets to construct g-C3N4@PdS@Pt nanocomposites. The photocatalytic activity of nanocomposites was evaluated under visible light and full spectrum irradiation. The results show that g-C3N4@PdS@Pt nanocomposites exhibit excellent properties. Under visible light irradiation, these nanocomposites exhibit a remarkable production rate of 1289 μmol·g-1·h-1, marking a staggering 60-fold increase compared to g-C3N4@Pt (20.9 μmol·g-1·h-1). Furthermore, when subjected to full spectrum irradiation, the hydrogen production efficiency of g-C3N4@PdS@Pt-3 nanocomposites reaches an impressive 11,438 μmol·g-1·h-1, representing an eightfold enhancement compared to g-C3N4@Pt (1452 μmol·g-1·h-1) under identical conditions. Detailed investigations into the microstructure and optical properties of g-C3N4@PdS catalysts were conducted, shedding light on the mechanisms governing photocatalytic hydrogen production. This study offers valuable insights into the potential of these nanocomposites and their pivotal role in advancing photocatalysis.

Prediction of pollutant removal from aqueous solutions using magnetic photocatalysts

In this research, magnetic nanocomposite (MGO@TiO2) consisting of Fe3O4, TiO2 and graphene oxide is synthesized for the photocatalytic removal of methyl orange, and its photocatalytic activity is compared with the nanohybrid (Fe3O4@TiO2) without graphene oxide. The crystalline phases of both photocatalysts are determined using X-ray diffraction patterns. The results show that the removal efficiency of methyl orange using the synthesized nanohybrid and nanocomposite is affected by the irradiation time and the pH of the suspension. Comparing the removal efficiency of methyl orange using synthesized photocatalysts shows that the photocatalytic activity of nanocomposite is much higher than that of nanohybrid. The statistical analysis of the experimental data using the response surface method led to the selection of the quadratic model as the best statistical model to estimate the removal efficiency of methyl orange. Also, the numerical and graphical methods confirmed the adequacy of the quadratic statistical model.

Nanocomposite from tannery sludge-derived biochar and Zinc oxide nanoparticles for photocatalytic degradation of Bisphenol A toward dual environmental benefits

The growing concern over the presence of pollutants like Bisphenol A (BPA) in water sources has led to the growth of novel treatment technologies for its removal. This research work investigates the development of a novel biochar-metal oxide nanocomposite derived from tannery sludge and Zinc oxide (ZnO) nanoparticles for the photodegradation of BPA. The biochar was obtained by pyrolysis process, followed by impregnation of ZnO nanoparticles using a hydrothermal technique. The critical properties of as-prepared nanocomposite were evaluated by FT-IR, BET surface area, XRD, FE-SEM, HR-TEM, XPS, PL, EPR, and Raman Spectroscopy. In addition, the photocatalytic activity of nanocomposites was evaluated by measuring the degradation of BPA in visible light irradiation. The outcomes revealed that ZnO-loaded chemically activated biochar exhibited higher photocatalytic activity for the degradation of BPA than the pristine and non-chemically activated biochar. At pH 5, 0.2 g/L of photocatalyst dosage, 20 ppm of initial pollutant concentration, and 150 min of contact time, the maximum degradation efficiency of BPA was observed as 94.50 %. Also, nanocomposites showed good stability and reusability, with only a slight decrease in photocatalytic activity after multiple cycles of use. More importantly, the degradation mechanisms of BPA using as-prepared nanocomposites were analyzed in detail, indicating that the observed photocatalytic activity could be attributed to the synergistic effect between the biochar and ZnO, which provided a large surface area for the adsorption of BPA and promoted the generation of reactive oxygen species for its degradation. Overall, this study highlighted the potential of using nanocomposites from tannery sludge-derived biochar and ZnO nanoparticles for the degradation of BPA from polluted water sources using a photocatalytic process toward the dual environmental benefits.

Application of a novel composite of Fe3O4@SiO2/PAEDTC surrounded by MIL-101(Fe) for photocatalytic degradation of penicillin G under visible light.

The novel photocatalyst of Fe3O4@SiO2/PAEDTC@MIL-101(Fe) was prepared based on the sol-gel method, and its structure and morphology were determined by SEM mapping, TEM, XRD, FTIR, and N2 adsorption-desorption analyses. The photocatalytic activity of nanocomposite was evaluated in comparison with other particles as well as adsorption and photolysis processes. The effect of operating parameters showed that the complete degradation of penicillin G (PNG) can be provided at a photocatalyst dosage of 0.6g/L, radiation intensity of 36 W, pH of 5, and time of 60min. In the optimum condition, 84% TOC removal was attained and the BOD5/COD rate for the treated effluent was above 0.4, which was representative of the high biodegradability of the treated effluent compared to the raw sample. The findings of energy consumption showed that PNG can be easily and effectively treated by the photocatalytic process based on magnetic MIL-101(Fe) with electrical energy per order between 10 and 20.87 kWh/m3. Due to the excellent interaction between the MIL-101(Fe) and Fe3O4@SiO2/PAEDTC, the photocatalyst stability test showed a recyclability of the particles for 5 consecutive reaction cycles with a minimum reduction of 7%. Solution treated with photocatalyst under UV and visible light sources explained that the toxicity of the effluent after treatment is significantly reduced with the growth of Escherichia coli. Scavenging experiments showed that •OH radical and hole (h+) are the main agents in degrading PNG to CO2, H2O, and biodegradable and low-toxicity products. Finally, the findings of the diagnostic analysis and comparative experiments proved that with the interaction of Fe3O4@SiO2, NH2, and MIL-101(Fe), a lower band gap can be prepared for more absorption of photons and pollutant and also more and faster production of active radicals.

Synthesis of highly efficient novel two-step spatial 2D photocatalyst material WS2/ZnIn2S4 for degradation/reduction of various toxic pollutants

In this article, we report the synthesis, characterization of novel biofriendly 2D/2D heterostructure WS2/ZnIn2S4 material in which 2D WS2 nanosheets are uniformly distributed spatially onto the spherically arranged 2D leaves of ZnIn2S4. We then studied the in-depth photocatalytic degradation activity of this novel nanocomposite and its pristine component materials on cationic dye: malachite green, anionic dye: congo red and reduction of heavy metal: chromium(VI) and the degradation efficiency of composite material was also tested on rhodamine-B, methylene blue, methyl orange dyes and acetaminophen/paracetamol drug. Form factor, structure factor and shape factor analysis has been carried out using X-ray diffractometry (XRD). Bond vibrations, functional groups and phonon vibration mode analysis has been done based on Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. Morphological and compositional analysis has been done using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM). Surface area and pore size/distribution was characterized using Brunauer–Emmett–Teller (BET) method and Barrett-Joyner-Halenda Model. Degradation pathways and intermediate products are proposed using the high-performance liquid chromatography (HPLC). Photocatalytic activity of the nanocomposite WS2/ZnIn2S4 is compared with pristine ZnIn2S4 and pristine WS2, which shows more than 50% enhancement in both efficiency and rate of degradation/reduction for all the pollutants. A scavenger study was carried out to get insight of primary and secondary reactive oxygen species (ROS) taking part in degradation. Exciton lifetime, surface charge and stability, and flat band positions were studied based on time-correlated single photon counting (TCSPC) also known as time-resolved photoluminescence (TRPL), zeta potential, and Mott-Schottky respectively. Rate kinetics study was performed to analyze the physical and chemical behaviour of the nanocomposite with pollutants in consideration. Results show ∼100%, ∼90%, and ∼95% degradation efficiency by the heterostructure for malachite green (MG), congo red (CR), and reduction of heavy metal chromium (Cr(VI)) respectively within 5 min, which is a huge improvement as compared to pristine WS2 and pristine ZnIn2S4, both of which show the efficiencies of only ∼25% to∼75% in all the cases.

Self-assembled quantum dots decorated polypyrrole based multifunctional nanocomposite

A modified sol-gel method was used for the synthesis of V/Mn/ZnO (VMZ) self-assembled ternary quantum dots (QDs). The polypyrrole (PPy) was polymerized through the chemical oxidative process. In situ technique was employed for synthesizing VMZ/PPy nanocomposites (NCs). FESEM, TEM, FTIR, UV–visible, Raman, DSC, PL, powder XRD, TGA and DSC were employed to characterize QDs and VMZ/PPy NCs. The theoretical (DFT) method was used to augment the experimental results. For the first time, we are reporting the electrical, adsorption, magnetic, photocatalytic, antibiotic, thermal, and photoluminescent, and anticorrosive properties of VMZ/PPy NCs. VMZ/PPy NCs show a para-magnetic character. The optical band obtained from DFT and UV–visible study was almost similar. For low-carbon steel, the NCs show a maximum of 83.08 ± 0.2% corrosion inhibition efficiency in 1 M HCl. The column packed with silica gel + QDs shows better adsorption capacity than the conventional silica-gel column. The photocatalytic activity of NCs was investigated against methyl-blue dye in UV light. The antibacterial property was investigated against Gram-positive and Gram-negative bacterial strains. The adsorption, magnetic, photocatalytic, electrical, antibiotic, thermal and photoluminescent, and anticorrosive properties of the VMZ/PPy NCs proved it a very good multifunctional nanomaterial.

Facile green synthesis of Ag-doped ZnO/CaO nanocomposites with Caccinia macranthera seed extract and assessment of their cytotoxicity, antibacterial, and photocatalytic activity.

The current paper exhibited a green method for the manufacture of Ag-doped ZnO/CaO nanocomposites (NCPs) by the usage of Caccinia macranthera seed extract, zinc, calcium, and silver salts solution, for the first time. The chemical structure of NCPs was studied by the FT-IR technique. The XRD pattern shows a crystallite structure with an Fm3m group space and particle size of about 23nm. The FESEM/PSA images displayed that NCPs have uniform distribution with spherical morphology. Also, the cytotoxicity of synthesized NCPs was examined on Huh-7 cells by MTT test and the IC50 value was 250ppm. Additionally, the photocatalytic activity of NCPs was investigated to the methylene blue MB dye degradation, which resulted in a removal of about 90% after 100min. According to the results of the broth microdilution process, which was done to evaluate the antibacterial activity of NCPs towards gram-positive and gram-negative bacteria, the MIC values were in the range of 0.97-125ppm.

Core-shell structuredCsPbBr3/Sn-TiO2 nanocrystals for visible-light-driven photocatalyst in aqueous solution

All-inorganic perovskite materials have attracted much attention in the field of photocatalysts due to their unique photoelectric properties.However, the inherent poor stability of perovskite quantum dots significantlyhinders their practical applications. Herein, to settle the instabilities of inorganic perovskite materials, Sn-TiO2 coated CsPbBr3 quantum dots named CsPbBr3/Sn-TiO2, are fabricated via resaturated recrystallization, sol–gel coating and solvothermal crystallization.The XRD results demonstrated that the core–shell structure of CsPbBr3/Sn-TiO2 nanocrystals was successfully synthesized.Moreover, excellent dispersion is verified for CsPbBr3/Sn-TiO2 nanocrystals with a core–shell structure by TEM. The particle size of CsPbBr3/Sn-TiO2 nanocrystals is 15–30 nm, where the core size for CsPbBr3 quantum dots is 4–8 nm, and the Sn-TiO2 shell thickness is 2–8 nm.The photocatalytic activity of nanocomposites was studied by the photodegradation of RhB aqueous solution under the irradiation of 100 mWcm−2 air mass 1.5 global AM1.5G sunlight. Compared with traditional photocatalyst P25, the core–shell structured CsPbBr3/Sn-TiO2 nanocrystals exhibited better photocatalytic performance, with a degradation efficiency of 96.6% and a degradation rate constant of 10.68 × 10-2 min−1 in 30 min of catalytic time, which was five times higher than that of P25.The core–shell structured CsPbBr3/Sn-TiO2 nanocrystals have long-term stability in water system and have potential practical application value in the field of environmental governance.

In-situ synthesis of 3D CdMoO4@CdS core-shell structure for efficient photocatalytic degradation

3D CdMoO4@CdS core-shell visible-light-driven photocatalyst was successfully synthesized by in-situ method. Various analytical techniques show that CdS dots are uniformly loaded on the surface of CdMoO4 hollow microspheres constructing a 3D core-shell CdMoO4@CdS heterojunction. The photocatalytic activity of nanocomposites was studied by degrading malachite green (MG) under visible light irradiation. It was found that the composite material can effectively degrade MG under visible light irradiation. Furthermore, the enhanced photocatalytic efficiency for the composite material is due to the effective diffusion and separation of photogenerated carriers.

Photodegradation of Synozol Red HF-6BN on g-C3N4/Halloysite nanocomposites

In the research, graphitic carbon nitride (g-C3N4) was synthesized using modified halloysite via a calcination method. The improvement of photocatalytic activity mainly benefits from the reduced e-/h+ pairs recombination rate, the improved electron separation yield. The photocatalytic activity of nanocomposite was evaluated through the Synozol red HF-6BN dye degradation, the degradation efficiency approached 99% after 30 mins irradiation under the solar light, and the performance is slightly reduced to 94 % after three consecutive tests. These results have demonstrated an effective method to synthesize g-C3N4 photocatalysts with nanostructures using crude clay minerals.

Chitosan-based nanocomposite films incorporated with NiO nanoparticles: Physicochemical, photocatalytic and antimicrobial properties

The aim of this research was to fabricate active nanocomposite films by incorporation of nickel oxide nanoparticles (NiONPs) (3, 6 and 9% w/w) into the chitosan-based films. The NiONPs were synthesized by solution combustion method and the films were prepared by solvent casting method. The formation of new interactions and increasing of films' crystallinity were confirmed by FT-IR and XRD analyses. Uniform dispersion of NiONPs at lower concentrations and their aggregation at level of 9% was confirmed by FE-SEM observations. Water barrier properties, tensile strength, thermal properties and surface hydrophobicity of films enhanced by addition of 6% NiONPs. Photocatalytic activity of nanocomposites was confirmed by absorption of 72% of methyl orange during 270 min under UV irradiation. The nanocomposite films exhibited good antibacterial activity against gram-positive (S. aureus) and gram-negative (S. typhimurium) bacteria. Therefore, the chitosan-NiONPs nanocomposite films could be used for active food packaging applications and photodecolorization purposes.

Synthesis and characterization of spinel FeV2O4 coupled ZnO nanoplates for boosted white light photocatalysis and antibacterial applications

Enhancement of photocatalytic activity of ZnO nanoplates was achieved by loading FeV2O4. The coexistence of FeV2O4 and ZnO in a single crystalline material was ensured by obtaining XRD pattern. XPS confirmed the chemical states present in FeV2O4-ZnO nanocomposites (NCs). The octahedral/tetrahedral M─O bonds presence was indicated in FTIR. High surface area (49.36 m2/g) was observed in NCs. White-light harvesting was facilitated due to the narrow bandgap in NCs (2.41 eV) compared with pure ZnO (3.1 eV). The magnetic property of NCs was validated by VSM analysis. The photocatalytic activity of NCs was 3.6 folds enhanced than pristine counter parts. Dye degradation is primarily carried out by generated ·OH radicals. The photocatalysis performance was almost same even after 5th cycle. The NCs exposure to Escherichia coli and Bacillus subtilis showed enhanced growth inhibition. The magnetically-removable FeV2O4-ZnO NCs can be applied for environmental remediation and antimicrobial application.

Coal fly ash-based copper ferrite nanocomposites as potential heterogeneous photocatalysts for wastewater remediation

Coal fly ash (CFA) based-copper ferrite nanocomposites were fabricated, characterized, and applied for the photocatalytic degradation of Methyl Orange (MO) dye. The hydrothermal synthesis route was opted for the fabrication of pristine copper ferrite nanoparticles and its CFA nanocomposites. The prepared photocatalysts were analyzed in terms of structural, surface morphology, chemical state analysis, elemental composition, and optical response. The photocatalytic activity of nanocomposites was investigated sequentially under ultraviolet light (254 nm) and influencing parameters (pH, H2O2 dose, photocatalyst content, dye initial concentration, irradiation time) were studied. The optimized conditions for photocatalytic degradation were found at pH = 5, composite dose = 100 mg/L, H2O2 = 10 mM using CFA nanocomposite and the dye was efficiently degraded within 60 min. The best degradation efficiency of ~98% was achieved using CFA-CuFe2O4 (1:1) under the optimized conditions. The key reactive species (OH, h+, and e−) for photocatalytic degradation were determined by a radical scavenging experiment and OH radicals were found to be the most effective ones. The kinetic study of Fenton oxidation processes was conducted using Behnajady-Modirshahla-Ghanbery (BMG) kinetic model. Response surface methodology was the statistical tool for the assessment of interaction effect among experimental variables.

A simple approach for the synthesis of bi-functional p-n type ZnO@CuFe2O4 heterojunction nanocomposite for photocatalytic and antimicrobial application

Photocatalysis is the versatile process that can be applied for water treatment, environmental remediation etc. A facile sonochemical-co-precipitation technique was adopted to prepare CuFe 2 O 4 decorated ZnO heterojunction nanocomposites (NCs). The characterization was done using UV–vis-DRS, TEM, EDAX, SAED , XRD, BET, PL and FTIR . The TEM reveals that the fabricated NCs were cubic in shape. The XRD and SAED analysis confirmed the crystalline nature of prepared NCs. The NCs band gap was determined to be 2.34 eV that facilitates enhanced performance of photocatalysis in visible region. The photocatalytic activity of NCs when irradiated with visible light was evaluated on basis of methylene blue (MB) dye degradation . The t½ for the degradation of 10 mg/L dye by 3 mg of NCs by photocatalysis was determined to be 77 min. The apparent rate constant of NCs was 4–5.1 times higher in NCs than CuFe 2 O 4 and ZnO respectively. At the end of 6 th recycle, the XRD pattern and NCs photocatalytic activity were retained the same as 1 st that denotes the high stable nature of NCs. The results indicate the enhanced activity of fabricated NCs relative to individual ZnO and CuFe 2 O 4 NPs. A possible photocatalysis mechanism was elucidated using charge carriers and free radicals scavengers. It was evident that ⋅OH radical and holes play the major role in dye degradation. The NCs acted as excellent antimicrobial agent against Bacillus subtilis and Escherichia coli . Hence, the investigation reports that ZnO@CuFe 2 O 4 NCs can be used as an efficient photocatalyst and as an antibacterial agent. • p-n type ZnO@CuFe 2 O 4 NCs was synthesized by chemical co-precipitation with ultrasonic assisted method. • The NCs were characterized by UV–vis-DRS, TEM, EDAX, SAED, XRD, BET, PL and FTIR analysis. • The photocatalytic activity was enhanced by 4–5.1 times than individual counter parts. • The mechanism of degradation was elucidated based on scavengers' responses. • The particles exhibited excellent antibacterial activity.

Simple synthesis of conductive poly aniline/cobalt ferrite magnetic nanocomposite: its radio waves absorption and photo catalyst ability

Photo-catalytic activity of cobalt ferrite/polyaniline magnetic nanocomposite was investigated for degradation of four Azo dyes (acid black, acid brown, acid violet and Congo red). For this purpose at the first step CoFe2O4 nanoparticles was synthesized via a fast and simple precipitation method. CoFe2O4/polyaniline nanocomposites were then prepared using simple polymerization method of aniline monomer. The absorption property of radio waves in the microwaves band by cobalt ferrite–polyaniline nanocomposites was studied as well. The results introduce the cobalt ferrite–polyaniline nanocomposites as a radar absorbing coatings. The crystal structure was studied using X-ray diffraction and particle size was determined by scanning electron microscopy. Vibrating sample magnetometer was used for magnetic analysis and by applying Fourier transform infrared spectrometer, the purity of the material was also determined. Photocatalytic activity of nanocomposites was investigated by analyzing UV–Vis spectrograph. In order to examine the radar absorption properties of cobalt ferrite/polyaniline nanocomposites, the absorption of radio waves in the range of 8–12 GHz was measured. These samples have absorption peaks around bandwidth 12–12.5 GHz and absorption amounts were about 70 percent and decrease reflecting was around − 6.4 dB frequency ranges.

CsPbBr3-MoS2-GO nanocomposites for boosting photocatalytic degradation performance

In order to address the main challenge of weak photocatalytic performance of pure metal halide perovskite materials, we innovatively introduced MoS2-graphene oxide (GO) composite structure and synthesized CsPbBr3-MoS2-GO nanocomposites by a two-step method. XRD and Raman results show that the three components are well combined to form a new CsPbBr3-MoS2-GO nanocomposite. TEM results show that MoS2 nanoribbons and CsPbBr3 quantum dots (QDs) are uniformly dispersed on the GO sheet. The photocatalytic activity of nanocomposites was evaluated by studying the photodegradation of Sudan Red III under xenon lamp irradiation. Benefiting from abundant active interfaces, the nanocomposites show much excellent photocatalytic degradation performance compared with pure CsPbBr3 QDs. The degradation rate of Sudan Red III by CsPbBr3-MoS2-GO nanocomposites is 3.1 times of that of pure perovskite QDs. Sudan Red III was completely photocatalytic degraded in 100 min. We believe that GO, with suitable band structure, high conductivity and good dispersibility, can bridge well MoS2 and CsPbBr3, act as a good electron transport channel, reduce carrier recombination and ultimately boost photocatalytic performance.

Controlling the kinetics of visible-light-induced photocatalytic performance of gold decorated graphitic carbon nitride nanocomposite using different proteins

In this work, the interaction of different proteins with two dimensional (2D) graphitic carbon nitride (GCN) nanosheets decorated with gold nanoparticles (Au NP) is reported along with their influence in controlling the visible-light-induced photocatalytic activity. The decoration of Au NP on 2D GCN nanosheets improves the photocatalytic activity as Au NP plays an important role in trapping and storing the conduction band electrons of GCN nanosheets. The structural, morphological and optical properties of Au-GCN (AGCN) nanocomposite have been investigated using scattering and spectroscopic techniques. Methylene blue (MB) dye was chosen as a representative system for the studying of visible-light-induced photocatalytic activity of AGCN nanocomposite in the presence of different proteins. Bovine serum albumin (BSA), trypsin and cytochrome C having different chain lengths and physicochemical properties were used to control the kinetics of the photocatalytic activity of GCN and AGCN nanocomposites. Due to the simultaneous competitive adsorption of MB and proteins, the photocatalytic activity of the nanocomposites got enhanced in the presence of BSA, while it got inhibited or slowed down in the presence of trypsin and cytochrome C, respectively. The observed photocatalytic activity could be correlated with the surface charges present on the proteins and the mechanistic understanding developed in this study can be beneficial in controlling the kinetics of the photocatalytic activity of semiconductor-based photocatalysts using proteins as activators or inhibitors.

Novel photocatalyst and antibacterial agent; direct dual Z-scheme ZnO–CeO2-Yb2O3 heterostructured nanocomposite

Novel excellent antibacterial agent and efficient photocatalyst direct dual Z-scheme ZnO–CeO2-Yb2O3 heterostructured nanocomposite and pristine ZnO, CeO2, and Yb2O3 were prepared via a simple co-precipitation technique. The X-ray diffraction spectra confirmed the formation of pristine ZnO, CeO2, and Yb2O3, and the existence of their peaks ZnO (hexagonal), CeO2 (cubic), and Yb2O3 (cubic) in the nanocomposite. The Scherrer, Williamson-Hall, and Size-Strain plot models were used to measure the microstructural parameters. The UV–vis spectroscopy revealed the energy bandgap 3.0 eV, evident that the grown nanocomposite is a good photocatalyst under sunlight. The formation of the ZnO–CeO2-Yb2O3 nanocomposite is further confirmed by Raman and Fourier transform infrared spectroscopy (FTIR). Current-Voltage (IV) measurements shown the ohmic nature of nanocomposite with high electrical behavior. Scanning electron microscopy (SEM) images revealed a cluster type morphology. The antibacterial activity was carried out for Escherichia coli and Staphylococcus aureus bacteria. The zone of inhibition (ZOI) showed higher antibacterial activity for E. coli bacteria. The nanocomposite showed the highest photocatalytic degradation efficiency against methylene blue as compared to rhodamine-B, methyl orange, cresol red, and safranin-O dyes under 40 min of sunlight illumination. The impact of various parameters on the photocatalytic activity of nanocomposite, including catalyst amount, dye concentration, and solution pH, was also investigated. The scavenger's experiments were performed to ascertain the reactive species and confirmed the mechanism based on Z-scheme. The recyclability test exhibits that the as-obtained nanocomposite has high stability and can be reusable for the 6th cycles.

Focus on the photocatalytic pathway of the CdS-AgBr nano-catalyst by using the scavenging agents

The CdS-AgBr nano-composite (NC) was prepared in-situ and characterized by XRD, SEM-EDX, UV–Vis DRS, and photoluminescence (PL) techniques. Crystallite size of about 53 nm was estimated for the NC sample by the Williamson-Hall equation. Then, the samples were used in the photodegradation of methylene blue (MB) in aqueous solution. In initial experiments, the photocatalytic activity of NC was 1.16 and 1.42 times greater than those of individual AgBr and CdS NPs in a 2 ppm MB solution without any optimization, respectively. The kinetic effects of some scavenging agents were studied to elucidate the photodegradation pathway and the change in k-values was compared statistically. For example, the average k-values of 9.13 × 10−2 and 5.02 × 10−2 for a 0.5 mM MB at pH 6 in the absence and presence of 0.5 mM nitrate were compared and an experimental t-value of 37.5 was obtained which is greater than the critical value of t0.05,4 = 2.78. This means that the two compared averages are significantly different at a 0.95% confidence interval. The scavenging effects depended on the solution pH and concentration of MB and the type of the scavenger. For example, a lower scavenging effect for carbonate species was observed at pH 2.5 concerning pH 4.5 and 9. The following trend was achieved for the investigated scavengers in a decrease in the rate of MB photodegradation process: Chloride > Carbonate > AA ≈ Nitrate, confirming the important roles of the photogenerated holes and hydroxyl radicals for the MB degradation. The results confirmed that the MB photodegradation pathway by the proposed composite proceeds via a direct Z-Scheme mechanism.