Novel Bi4O5Br2/MnxZn1-xFe2O4 magnetic composite with an enhanced photodegradation activity and excellent recyclability

Bi₄O₅Br₂/Mn_xZn_1-xFe₂O₄ nanocomposites with impressive photocatalytic and recyclability properties were synthesised using a microemulsion method. In addition to the photocatalytic effect, the crystal structure and morphology, photoelectrochemical characteristics, magnetic effect and photocatalytic mechanism of Bi₄O₅Br₂/Mn_xZn_1-xFe₂O₄ were also investigated. As the best sample, the removal rate of the Bi₄O₅Br₂/Mn_xZn_1-xFe₂O₄ photocatalyst with 7.5 wt% Mn_xZn_1-xFe₂O₄ to rhodamine B (RhB) reached up to 99.4% within 60 min. The enhanced photocatalyst activity was mainly attributed to the type-II heterojunction formed between Bi₄O₅Br₂ and Mn_xZn_1-xFe₂O₄, which not only optimised the energy band structure, but also led to the building of an interior electromagnetic field within the Bi₄O₅Br₂/Mn_xZn_1-xFe₂O₄ heterojunction. Meanwhile, the constantly producing and migrating h⁺ and ·O₂^? were the main active components. In particular, the results of the saturation magnetization tests and magnetic recovery experiments revealed that the magnetic composite photocatalyst can be recovered effectively. The results of the removal rate of RhB remaining at 85.2% after five uses reflected the advantages of the stability of the Bi₄O₅Br₂/Mn_xZn_1-xFe₂O₄ photocatalyst. In brief, this paper presented an original idea to develop a novel composite magnetic photocatalyst and research the enhancement mechanism of photocatalysis.     

Magnetically recyclable Ni1-xCdxCeyFe2-yO4-rGO nanocomposite photocatalyst for visible light driven photocatalysis

In this study, a magnetically recyclable Ni_1-xCd_xCe_yFe_2-yO₄-rGO (x, y = 0.05) (NCCF-rGO) nanocomposite photocatalyst has been prepared by following a facile in-situ co-precipitation method combined with ultra-sonication means. The as-synthesized magnetically separable NCCF-rGO nanocomposite photocatalyst efficiently degrades methylene blue (MB) dye in comparison to bare Ni_1-xCd_xCe_yFe_2-yO₄ (x, y = 0.05) (NCCF) nanoparticles (NPs) under visible light irradiation. The photo-degradation rate of MB with NCCF-rGO was ~9 times higher than NCCF nanoparticles (NPs). This enhanced photocatalytic performance of NCCF-rGO photocatalyst was due to the presence of reduced graphene oxide, which greatly help in production of photoactive species by reducing the rate of electro-hole pair recombination. The role of photoactive species that were responsible for the photocatalytic degradation of methylene blue has also been investigated. The as-synthesized NCCF-rGO photocatalyst expressed superb chemical stability and photocatalytic activity even after seven cycle runs. Moreover, the NCCF-rGO nanocomposite worked at all pH values and showed good acid resistance. In particular, the as-synthesized NCCF-rGO photocatalyst could be collected for the next cycle run by simply applying an external magnetic field. Hence, the NCCF-rGO nanocomposite could have potential use in organic dyes contained wastewater treatment.     

One-step electrosynthesis of MnO2/rGO nanocomposite and its enhanced electrochemical performance

We present a facile one-step electrochemical approach to generate MnO₂/rGO nanocomposite from a mixture of Mn₃O₄ and graphene oxide (GO). The electrochemical conversion of Mn₃O₄ into MnO₂ through potential cycling is expedited in the presence of GO while the GO is reduced into reduced graphene oxide (rGO). The MnO₂ nanoparticles are evenly distributed on the rGO nanosheets and act as the spacer to prevent rGO nanosheets from restacking. This unique structure provides high electroactive surface area (1173?m² g^?1) that improves ions diffusion within the MnO₂/rGO structure. As a result, the MnO₂/rGO nanocomposite exhibits high specific capacitance of 473?F?g^?1 at 0.25?A?g^?1, which is remarkably higher (3 times) than the Mn₃O₄/GO prior conversion. In addition, the electrosynthesized nanocomposite shows higher conductivity and excellent potential cycling stability of 95% at 2000 cycles.     

Wet-chemical synthesis of urchin-like Co-doped CuO: A visible light trigger photocatalyst for water remediation and antimicrobial applications

The semiconductive material must have a large surface area and a visible light active bandgap in order to be selected for photocatalytic applications. Herein, we fabricate an urchin-like Co_xCu_1-xO photocatalyst with a visible light-triggered bandgap and high surficial properties using nanotechnology, doping, and chemical activation approaches. X-ray diffraction and optical analysis revealed that the Co_xCu_1-xO sample possesses a high porosity (%) and a visible light active bandgap (1.59 eV). Furthermore, the Co_xCu_1-xO sample showed greater electrical conductivity than the pristine CuO photocatalyst, which positively influenced the kinetics of the photocatalysis process. The antibacterial and photocatalytic performances of the synthesized materials have been investigated and compared by employing bacterial strains and organic pollutants (Methylene-blue), respectively. The results of the antibacterial assay, conducted on Escherichia coli (E.coli), showed that the Co_xCu_1-xO sample possessed excellent antibacterial activity. Concerning the photocatalytic activity, we noted that among the doped and undoped materials tested for their Methylene-blue degradation capacity, the Co_xCu_1-xO catalyst demonstrated outstanding activity with a removal efficiency of 92.6% over 90 min. In contrast, the pristine CuO showed comparatively poor performance, with a removal efficiency of merely 53.75%. The superior photocatalytic activity observed in the case of Co_xCu_1-xO was attributed to its enhanced surface area, porous surface, good electronic conductivity, lower bandgap, and nanoarchitecture. Our study points towards a potential strategy for preparing a simple and efficient photocatalyst to mineralize dye and kill pathogenic microbes.     

A unique Cu2O/TiO2 nanocomposite with enhanced photocatalytic performance under visible light irradiation

A unique Cu₂O/TiO₂ nanocomposite with high photocatalytic activity was synthesized via a two-step chemical solution method and used for the photocatalytic degradation of organic dye. The structure, morphology, composition, optical and photocatalytic properties of the as-prepared samples were investigated in detail. The results suggested that the Cu₂O/TiO₂ nanocomposite is composed of hierarchical TiO₂ hollow microstructure coated by a great many Cu₂O nanoparticles. The photocatalytic performance of Cu₂O/TiO₂ nanocomposite was evaluated by the photodegradation of methylene blue (MB) under visible light, and compared with those of the pure TiO₂ and Cu₂O photocatalysts synthesized by the identical synthetic route. Within 120 min of reaction time, nearly 100% decolorization efficiency of MB was achieved by Cu₂O/TiO₂ photocatalyst, which is much higher than that of pure TiO₂ (26%) or Cu₂O (32%). The outstanding photocatalytic efficiency was mainly ascribed to the unique architecture, the extended photoresponse range and efficient separation of the electron-hole pairs in the Cu₂O/TiO₂ heterojunction. In addition, the Cu₂O/TiO₂ nanocomposite also retains good cycling stability in the photodegradation of MB.     

Effect of dopant on ferroelectric,dielectric and photocatalytic properties of Co–La-doped dysprosium chromite prepared via microemulsion route

In the current study, pristine and a series of La and Co-doped dysprosium chromite (Dy_1-yLa_yCr_1-xCo_xO₃) nanoparticles have been fabricated via a facile microemulsion technique. The influence of doping was evaluated based on structural, ferroelectric, dielectric, and photocatalytic properties. The prepared nanoparticles were characterized by XRD, SEM, Raman, and UV–Vis techniques. XRD patterns confirm the synthesis of a monophase orthorhombic structure with space group Pbnm with an average crystalline size in the 18–37 nm range. The saturation polarization (Ps), remanence (Pr), and coercivity (Hc) were determined using a hysteresis loop, and it was observed that by increasing the concentration of dopants, the value of Ps and Pr were improved. According to the PL spectra, highly substituted materials had a low recombination rate and higher charge separation (e^? - h⁺), which was ultimately accountable for higher photocatalytic activity. The dielectric loss decreases with frequency and dopant concentration. The photocatalytic activity of Dy_1-yLa_yCr_1-xCo_xO₃ was investigated against Crystal Violet (CV) dye under sunlight irradiation. The Dy_1-yLa_yCr_1-xCo_xO₃ furnished a 70% dye degradation in 90 min, which is attributed to the tunned bandgap and efficient electron-hole pair separation and the photocatalytic activity under visible light making Dy_1-yLa_yCr_1-xCo_xO₃ a promising photocatalyst for dye removal from wastewater.     

Fabrication of novel Mn0.43Cd0.57S/ZnCo2O4 p-n heterojunction photocatalyst with efficient charge separation for highly enhanced visible-light-driven hydrogen evolution

The construction of efficient and low-cost photocatalytic systems is a major challenge in the field of photocatalysis. An efficient heterojunction photocatalyst designed for water splitting is also an interesting prospect in energy conversion. In this study, a novel Mn_0.43Cd_0.57S/ZnCo₂O₄ p-n heterojunction photocatalyst was prepared via a simple solvothermal method. Mn_0.43Cd_0.57S was loaded on the surface the of noble metal-free transition metal oxide ZnCo₂O₄ to prevent the agglomeration of particles, resulting in efficiently improving the photocatalytic performance of the material. Due to the Fermi level balance, the band bending of the two materials constructs a p-n heterojunction, which stimulates the transfer of photogenerated electrons from the CB of Mn_0.43Cd_0.57S to the CB of ZnCo₂O₄. The uniformly dispersed p-n heterojunction structure effectively suppresses the recombination of photoinduced charges and preserves stronger redox charges. As a result, the established Mn_0.43Cd_0.57S/ZnCo₂O₄ heterojunction showed the best photocatalytic hydrogen production concentration (92.1 mmol g^?1 h^?1), which was 4.7 times that of the original Mn_0.43Cd_0.57S (19.4 mmol g^?1 h^?1) and 54.2 times that of ZnCo₂O₄ (1.7 mmol g^?1 h^?1). This strategy will provide new insights into the development of new photocatalysts.     

Electrical Properties of Triethylene Glycol Stabilized MnxCo1-xFe2O4 Nanoparticles

We reported on the synthesis and analysis of the composition, micro-structure, ac–dc conductivity performance and dielectric permittivity of triethylene glycol (TEG) stabilized Mn_xCo_1-xFe₂O₄ nanoparticles obtained by polyol method. Crystallite size from XRD and particle size from TEM micrographs are consistent with each other. Conductivity measurements were performed to investigate the influence of the coating with TEG on the conduction characteristics of Mn_xCo_1-xFe₂O₄ NP’s. The frequency-dependency of the ac conductivity shows electrode polarization effect. The dc conductivity is strongly temperature dependent and shows maximum conductivity of about 5 × 10^?5 S cm^?1 for x = 1.0 at 120 °C. Analysis of dielectric permittivity functions suggests that ionic and polymer segmental motions are strongly coupled.     

Cost effective synthesis of CuxBi2-xSe3 photocatalysts by sol-gel method and their enhanced photodegradation and antibacterial activities

A simple sol-gel approach was used to synthesize Cu doped Bismuth Selenide nanoparticles denoted as Cu_xBi_2-xSe₃ (x = 0.1, 0.2), in order to comprehend the effect of Cu-dopant on the photocatalytic and antibacterial activity of Bismuth Selenide. The structural properties of prepared samples were investigated by the XRD technique and results showed the formation of hexagonal Cu_xBi_2-xSe₃ (x = 0.1, 0.2). The average crystallite size of Cu_xBi_2-xSe₃ was found to increase from 39 nm to 42 nm with the increase in the concentration of Cu ions. Atomic force microscopy (AFM) was used to confirm the morphology and particle size of prepared samples. Photoluminescence (PL) studies revealed the decrease in band gap from 1.66 eV to 1.61 eV for Cu_0.1Bi_1.9Se₃ and Cu_0.2Bi_1.8Se₃, respectively. The Raman spectra of Cu_xBi_2-xSe₃ (x = 0.1, 0.2) showed two vibrational modes at 130 cm^?1 and 170 cm^?1. The photocatalytic performance of prepared nanoparticles was evaluated by the removal of methyl blue (MB) and malachite green (MG), under natural sunlight. Cu doped Bismuth Selenide Cu_0.2Bi_1.8Se₃ exhibited higher photocatalytic activity as compared to Cu_0.1Bi_1.9Se₃ and undoped Bismuth Selenide with the 97% and 99% degradation of MB and MG, respectively. Hence, Cu doping proved an efficient way to enhance the photocatalytic response of Bismuth Selenide. Through the antibacterial activity, it was further disclosed that the Cu doped samples had better inhibition zones than undoped Bismuth Selenide. The maximum inhibition zone (29 mm) was observed at optimum doping concentration for Cu_0.2Bi_1.8Se₃. From the results, it can be deduced that Cu_0.2Bi_1.8Se₃ can be as effective photocatalytic and antibacterial agent to treat water pollution.     

Ferroelectric,dielectric, magnetic,structural and photocatalytic properties of Co and Fe doped LaCrO3 perovskite synthesized via micro-emulsion route

In the present investigation, La_1-xCo_xCr_1-yFe_yO₃ (x,y = 0.0, 0.12, 0.36, 0.60) perovskite was fabricated via a facile micro-emulsion route. The synthesized perovskites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques to examine the effect of Co and Fe ions on the physico-chemical properties. The ferroelectric, dielectric, and magnetic properties of La_1-xCo_xCr_1-yFe_yO₃ were changed significantly as a function of dopants contents (Co and Fe ions). Outcomes revealed that the dielectric, ferroelectric and magnetic properties of LaCrO₃ perovskite can be tuned significantly via Co and Fe doping and La_0.40Co_0.60Cr_0.40Fe_0.60O₃ have potential for photocatalytic dye removal under (visible) light expoure. The photocatalytic activity (PCA) of the pristine LaCrO₃ and La_0.40Co_0.60Cr_0.40Fe_0.60O₃ photocatalyst was evaluated under (visible) light irradiation for crystal violet (CV) dye. Experimental results revealed that La_0.40Co_0.60Cr_0.40Fe_0.60O₃ photocatalyst degrdae almost 77.21% CV dye with the rate constant value of 0.01475 min^?1. In the presence of isopropyl alcohol (IPA) scavenger, the PCA of the La_0.40Co_0.60Cr_0.40Fe_0.60O₃ photocatalyst and rate constant value of the photocatalytic reaction decreased to 32.5% and 0.00491 min^?1, suggesting the superoxide as main active specie. Results revealed that Co and Fe doping doped material is efficient for photocatalytic presentations under solar light expoure.     

Hydrothermal preparation of Sn3O4/TiO2 nanotube arrays as effective photocatalysts for boosting photocatalytic dye degradation and hydrogen production

The efficient TiO₂ NTs/Sn₃O₄ photocatalysts were synthesized by the hydrothermal deposition of Sn₃O₄ on TiO₂ nanotube arrays (TiO₂ NTs), and the morphology, microstructure and photocatalytic property were adjusted by changing the alkali kind. The TiO₂ NTs/Sn₃O₄ prepared with NaOH exhibited the outstanding photoelectric conversion and photocatalytic environment remediation/H₂ evolution. The methylene blue (MB) dye and Cr(VI) could be removed by the as-prepared photocatalysts under visible light irradiation, and ?O₂^?/?OH radicals were the main active species for MB photodegradation. Furthermore, the high photocatalytic H₂ evolution rate was as high as 6.49 μmol cm^?2 h^?1. The outstanding photocatalytic activity and stability of TiO₂ NTs/Sn₃O₄ photocatalysts would exhibit attractive prospect in the wastewater remediation and electric energy/hydrogen generation.     

Synthesis and Photocatalytic Properties of Single Crystalline (Ga1-xZnx)(N1-xOx) Nanotubes

Recently, (Ga_1-xZn_x)(N_1-xO_x) has gained widespread attention as a comparatively high efficiency photocatalyst for visible-light-driven overall water splitting. Despite significant gains in efficiency over the past several years, a majority of the photogenerated carriers recombine within bulk powders. To improve the photocatalytic activity, we used an epitaxial casting method to synthesize single-crystalline, high surface area (Ga_1-xZn_x)(N_1-xO_x) nanotubes with ZnO compositions up to x=0.10. Individual nanotubes showed improved homogeneity over powder samples due to a well defined epitaxial interface for ZnO diffusion into GaN. Absorption measurements showed that the ZnO incorporation shifts the absorption into the visible region with a tail out to 500 nm. Gas chromatography (GC) was used to compare the solar water splitting activity of (Ga_1-xZn_x)(N_1-xO_x) nanotubes (x=0.05–0.10) with similar composition powders. Cocatalyst decorated samples were dispersed in aqueous solutions of CH₃OH and AgO₂CCH₃ to monitor the H⁺ reduction and H₂O oxidation half reactions, respectively. The nanotubes were found to have approximately 1.5–2 times higher photocatalytic activity than similar composition powders for the rate limiting H⁺ reduction half reaction. These results demonstrate that improvements in homogeneity and surface area using the nanotube geometry can enhance the photocatalytic activity of GaN:ZnO for solar water splitting.     

Preparation and photocatalytic activity of BiOI/MnxZn1-xFe2O4 magnetic photocatalyst

BiOI/Mn_xZn_1-xFe₂O₄ magnetic photocatalysts were successfully prepared for the first time. With the degradation of simulated RhB wastewater as a pointer to the photocatalytic reaction and combined with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and vibrating sample magnetometer (VSM), the reasons influencing the photocatalytic performance of the magnetic photocatalysts were further explored. The excessive or insufficient Mn-Zn ferrite both leads to a relatively low photocatalytic activity. When the calcination temperature reaches to 200 and 400?°C, the photocatalytic activity is enhanced significantly, but the main active component in the photocatalysts has changed from BiOI to Bi₅O₇I at 400?°C. The nanocomposites prepared under alcohol water environment with hollow microspheres morphology possess a highly photocatalytic efficiency, and the RhB degradation rate within 4?h in the ethanol water environment is significantly higher than that in pure water (98% vs. 59%).     

Carbon-based TiO2-x heterostructure nanocomposites for enhanced photocatalytic degradation of dye molecules

Application of brown titanium dioxide (TiO_2-x) and its modified composite forms in the photocatalytic decomposition of organic pollutants in the environment is a promising way to provide solutions for environmental redemption. Herein, we report the synthesis of effective and stable TiO_2-x nanoparticles with g-C₃N₄, RGO, and multiwalled carbon nanotubes (CNTs) using a simple hydrothermal method. Among all the as-synthesized samples, excellent photocatalytic degradation activity was observed for RGO-TiO_2-x nanocomposite with high rate constants of 0.075 min^?1_, 0.083 min^?1 and 0.093 min^?1 for methylene blue, rhodamine-B, and rosebengal dyes under UV–Visible light irradiation, respectively. The altered bandgap (1.8 eV) and the large surface area of RGO-TiO_2-x nanocomposite impacts on both absorption of visible light and efficiency of photogenerated charge electron (e^?)/hole (h⁺) pair separation. This resulted in enhanced photocatalytic property of carbon-based TiO_2-x nanocomposites. A systematic study on the influence of different carbon nanostructures on the photocatalytic activity of brown TiO_2-x is carried out.     

Novel high-capacity hybrid layered oxides NaxLi1.5-xNi0.167Co0.167Mn0.67O2 as promising cathode materials for rechargeable sodium ion batteries

Relatively low capacity is a technological bottleneck of the development of sodium ion batteries. Herein, we present a series of hybrid layered cathode materials Na_xLi_1.5-xNi_0.167Co_0.167Mn_0.67O₂ (x?=?0.5, 0.6, 0.7, 0.8, 0.9, 1) with composite crystalline structures, which are prepared by co-precipitation method. The combined analysis of XRD, SEM and TEM reveals that the materials are composed of P2 structure, α-NaFeO₂ structure and small amount of Li₂MnO₃. Among the as-prepared materials, Na_0.6Li_0.9Ni_0.167Co_0.167Mn_0.67O₂ delivers an initial reversible capacity of 222?mA?h?g^?1 at 20?mA?g^?1. Even at 100?mA?g^?1, it shows a remarkable discharge capacity of 125?mA?h?g^?1 in the first cycle and remains 60?mA?h?g^?1 after 300 cycles. Such high capacity is achieved by the specific composite structure and sodium ions are proved to be able to intercalate/deintercalate in Li_1.5Ni_0.167Co_0.167Mn_0.67O₂ with α-NaFeO₂ structure. The Ex-situ XRD results of Na_0.6Li_0.9Ni_0.167Co_0.167Mn_0.67O₂ in the first cycle show that the P2 structure is well maintained along with irreversible phase transition of α-NaFeO₂ structure, which is responsible for the long-term capacity fading. Owing to the high discharge capacity, the novel hybrid layered oxides Na_xLi_1.5-xNi_0.167Co_0.167Mn_0.67O₂ with composite structures can be considered as promising cathode materials to promote progress toward sodium-ion batteries.     

Manganese spinel ferrite-reduced graphene oxides nanocomposites for enhanced solar irradiated catalytic studies

An excellent photocatalyst must have narrow band gap value, broad absorption range and high electrical conductivity. The co-precipitation route was followed to synthesize copper substituted manganese ferrite nanoparticles because the co-precipitation is a facile, short and easy to handle method. The nanocomposite of copper substituted manganese ferrite with rGO was synthesized by sonication method. The graphene was used for composite synthesis because of its extraordinary properties such as chemical stability, high transparency, large surface area, high electron transfer ability. Graphene can also improve catalytic acitivity of spinal ferrites. X-ray diffraction (XRD), Raman spectroscopy, and field emission scanning electron microscopy (FESEM) were employed to confirm the structural, spectral and morphological aspects of prepared nanomaterials and their composites with rGO. XRD confirmed face centered cubic (FCC) crystal structure. The appearance of relative broad peaks estimated the formation of nanocrystalline size of synthesized samples. SEM images showed that the nanoparticles have spherical morphology. Furthermore, rGO sheets can be clearly seen in SEM images of composite material. It was investigated that electrical conductivity of MnF₂O₄ was increased by the substitution of metal cations such as copper. Current – voltage measurements were carried out at room temperature and confirmed the enhanced conductivities of copper doped manganese ferrite and its rGO based nanocomposite. These photocatalysts were used for the degradation of methylene blue (MB) dye and Mn_0.9Cu_0.1Fe₂O₄/rGO nanocomposite showed great activity in photocatalysis experiment with 77% degradation efficiency. This increment in photocatalysis was found to be due to synergistic effect of ferrite material and rGO sheets, which increases the electrical conductivity and decreases the photoexcited electrons-holes pair recombination of composite materials.     

Preparation and Photocatalytic Activity of (Cu0.94La0.06)2SnO4 Nanocomposite Photocatalyst Under Simulated Sunlight

Abstract  

A series of (Cu_0.94La_0.06)₂SnO₄ photocatalysts were prepared under different calcination temperatures using a simple co-precipitation method. The crystalline structures of the as-prepared photocatalysts, as well as their particle sizes, photo absorption, and the effect of calcination temperature, were investigated using x-ray powder diffraction, Brunauer–Emmett–Teller method, transmission electron microscopy, and UV−Vis diffuse reflectance spectroscopy, respectively. The photocatalytic activity of (Cu_0.94La_0.06)₂SnO₄ nanocomposite oxide was evaluated using the photodegradation efficiency of acid blue 62 (AB62) as a probe under simulated sunlight irradiation. The photocatalytic experimental results show that the maximum specific photocatalytic activity of the (Cu_0.94La_0.06)₂SnO₄ photocatalyst appears after calcination at 450 °C for 2.5 h because of the good crystallization and small crystal size of the sample. Under simulated sunlight irradiation, the AB62 aqueous solution can reach a degradation rate of 97.71% in 2 h, showing that the (Cu_0.94La_0.06)₂SnO₄ nanocomposite photocatalyst has a much higher photocatalytic activity than the standard Degussa P25 photocatalyst.     

Synthesis of Ni doped barium hexaferrite by microemulsion route to enhance the visible light-driven photocatalytic degradation of crystal violet dye

The pristine and Ni doped BaNi_xFe_12-xO₁₉ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) NPs have been fabricated via facile microemulsion approach and the impact of dopants was explored based dielectric, optical, structural and the photocatalytic properties of BaNi_xFe_12-xO₁₉ nanoparticles. X-ray diffraction and Raman study confirmed the formation of regular hexagonal geometry with space group P6₃/mmc with crystallite size in 32–50 nm range. Functional groups were identified using FTIR analysis. The remanence (Pr), saturation polarization (Ps) and coercivity (Hc) was explored by P-E loop analysis and the value of Pr and Ps was enhanced with the concentration of dopant. According to PL spectra, highly doped materials had a higher charge separation (e^?- h⁺) and low recombination rate, which resulted in higher photocatalytic degradation activity of fabricated nanomaterials. The optical band gap was found to be 1.78 eV versus undoped (2.60 eV for pristine BaFe₁₂O₁₉). Due to polarizations, the dielectric loss, dielectric constant and tangent loss values were declined, while AC conductivity was enhanced. Photocatalytic performance of doped and undoped samples under visible right irradiation was studied for crystal violet dye. For 100 min exposure to visible light, the highly doped catalyst exhibits 97% degradation versus 60% in case of pristine this is attributed to efficient electron-hole pair separation. Furthermore, quenching effect of different scavengers indicated that hydroxyl radical had a main role, and e^? or h⁺ played a minimal role in CV dye degradation. The enhanced properties due to doping make BaNi_xFe_12-xO₁₉ a potential candidate for photocatalytic applications under visible light irradiation.     

Role of A-site (Sr), B-site (Y), and A,B sites (Sr,Y) substitution in lead-free BaTiO3 ceramic compounds: Structural,optical, microstructure,mechanical, and thermal conductivity properties

Strontium and Yttrium-doped and co-doped BaTiO₃ (BT) ceramics with the stoichiometric formulas BaTiO₃, B_1-xSr_xTiO₃, Ba_1-xY_xTiO₃, BaTi_1-xY_xO₃, Ba_1-xY_xTi_1-xY_xO₃, and Ba_1-xSr_xTi_1-xY_xO₃ (x = 0.075) noted as BT, BSrT, BYT, BTY, BYTY, and BSrTY have been synthesized through sol-gel method. X-ray diffraction (XRD) patterns of the prepared ceramics, calcined at a slightly low temperature (950 °C/3h), displayed that BT, BSrT, and BYT ceramics possess tetragonal structures and BTY, BYTY, and BSrTY have a cubic structure. The incorporation of the Ba and/or Ti sites by Sr²⁺ and Y³⁺ ions in the lattice of BaTiO₃ ceramic and the behaviors of the crystalline characteristics in terms of the Y and Sr dopant were described in detail. The scanning electron microscopy (SEM) images demonstrated that the densification and grain size were strongly related to Sr and Y elements. UV–visible spectroscopy was used to study the optical behavior of the as-prepared ceramic samples and revealed that Sr and Y dopants reduce the optical band gap energy to 2.74 eV for the BSrTY compound. The outcomes also demonstrated that the levels of Urbach energy are indicative of the created disorder following the inclusion of Yttrium. The measurements of the thermal conductivity indicated the influence of the doping mechanism on the thermal conductivity results of the synthesized samples. Indeed, the thermal conductivity of BaTiO₃ is decreased with Sr and Y dopants and found to be in the range of 085–2.23 W.m^-1. K^?1 at room temperature and decreases slightly with increasing temperature from 2.02 to 0.73-W.m^-1. K^?1. Moreover, the microstructure and grains distribution of the BT, BSrT, BYT, BTY, BYTY, and BSrTY samples impacted the compressive strength, hence; the compressive strength was minimized as the grain size decreased.     

Novel g-C3N4 nanosheets/CDs/BiOCl photocatalysts with exceptional activity under visible light

We fabricated novel ternary nanocomposites through integration of C-dots (carbon dots), BiOCl, and nanosheets of graphitic carbon nitride (g-C₃N₄ nanosheets) by a cost-effective route. The fabricated photocatalysts were subsequently characterized by XRD, EDX, TEM, HRTEM, XPS, FT-IR, UV-vis DRS, TGA, BET, and PL methods to gain their structure, purity, morphology, optical, textural, and thermal properties. In addition, the degradation intermediates were identified by gas chromatography-mass spectroscopy (GC-MS). Photocatalytic performance of the synthesized samples was studied by photodegradations of three cationic (RhB, MB, and fuchsine), one anionic (MO) dyes, one colorless (phenol) pollutant and removal of an inorganic pollutant (Cr(VI)) under visible light. It was revealed that the ternary nanocomposite with loading 20% of BiOCl illustrated superlative performances in the selected photocatalytic reactions compared with the corresponding bare and binary photocatalysts. Visible-light photocatalytic activity of the g-C₃N₄ nanosheets/CDs/BiOCl (20%) nanocomposite was 42.6, 27.8, 24.8, 20.2, and 15.9 times higher than the pure g-C₃N₄ for removal of RhB, MB, MO, fuchsine, and phenol, respectively. Likewise, the ternary photocatalyst showed enhanced activity of 15.3 times relative to the g-C₃N₄ in photoreduction of Cr(VI). Moreover, the ternary nanocomposite exhibited excellent chemical stability and recyclability after five cycles. Finally, the mechanism for improved photocatalytic performance was discussed based on the band potential positions.