Lower Band Gap Energy Research Articles

Facile synthesis of Cu-doped BiVO4 using domestic microwave-assisted chemical precipitation method with fleeting time of microwave irradiation for the photocatalytic application

Semiconductor-based visible light active photo-catalyst has been synthesized through microwave-assisted chemical precipitation method under acidic pH with minimal time of reaction using microwave irradiation. The monoclinic crystal phase of the material with no impurity is confirmed with XRD data. We can observe slight left shift after doping with copper (Cu) in 2Θ peak of XRD data. SEM analysis exhibits a gradual change in morphology with the increase in doping concentration. UV–Vis data confirms an improvement in absorption with the increase in dopant concentration. PL analysis further clarifies the change in recombination rate of photo-induced charge carriers. Photocatalysis has been tested with methylene blue (MB) synthetic dye. The maximum percentage of degradation was determined to be 61.08% and it is obtained for 0.25% Cu-doped BiVO4. It is also observed that 0.25% Cu-doped BiVO4 has lower energy band gap value, i.e., 2.03 eV and lesser PL intensity than pure un-doped BiVO4. The HRTEM analysis proves that 0.25% Cu-BiVO4 is well crystalline in nature with the d spacing corresponding to (121) plane of BiVO4.

Cu-doped mesoporous TiO2 photocatalyst for efficient degradation of organic dye via visible light photocatalysis

A solvothermal method was used to synthesize the mesoporous TiO2, (1-3w %) Cu-doped mesoporous TiO2 membrane with the help of a bioreactor. To understand the physicochemical composition of all synthesized nanomaterials, the structure, morphology and crystallinity of the materials were studied using X-ray diffractometer (XRD), Field emission scanning electron microscopy (FESEM), Fourier transform-infrared (FTIR), Energy dispersive X-ray spectroscopy (EDS) and cyclic voltammetry (CV). Under artificial light source (500 W mercury bulb) irradiations, the nano catalysts' catalytic effectiveness was examined for the azo dyes, namely Congo red. Cu-doping causes a shift in the light absorption of mTiO2 from the ultraviolet to the visible region. The 3w% Cu-doped mTiO2 photocatalyst exhibits lower band gap energy (2.6eV) than TiO2 which is 3.2 eV to efficiently utilize solar energy. As a result, the light absorption was shifted towards the visible spectrum. The recommended mTiO2 and (1, 2, 3) w% Cu-doped mTiO2 photocatalysts were used to photodegrade Congo red and methylene blue. For the degradation of CR, the mTiO2 photocatalyst exhibited 61% and 3w% Cu-doped mTiO2 demonstrated 99% photocatalytic performance after 50 min. A variety of scavengers were also utilized to distinguish the active species by catching the radicals and holes created during the process of photocatalytic degradation. CV indicates the presence of Cu2+ and Cu1+ in Cu-doped mTiO2. Oxygen vacancies and the electronegative surface of Cu1+ seem to perform the photocatalytic reduction of CR.

Influence of copper and iron transition metals in the photocatalytic activity of titanium dioxide microspheres

This work proposes the combined sol–gel/solvothermal synthesis method to prepare Cu-doped TiO2 and Fe-doped TiO2 microstructures, and further study their photocatalytic activity in the degradation of Eriochrome Black T (EBT) at neutral conditions using a simulated sunlight source. TiO2:at%M (at%=0.25, 0.5, and 1.0; M = Cu or Fe) catalysts were characterized by X-ray diffractometry, Scanning electron microscopy, Diffuse reflectance UV–Vis spectroscopy, Raman spectroscopy, and Brunauer-Emmett-Teller surface area analysis. All synthesized catalysts showed TiO2 anatase phase with spherical morphology and average particle size of 4 to 8 μm. Transition metal doping did not modify the TiO2 anatase phase. TiO2:at%M catalysts exhibited lower bandgap energies than pure TiO2. TiO2:0.5at%Fe showed the lowest bandgap energy (2.87 eV). TiO2 catalysts with a transition metal content of 0.25at% showed a higher surface area compared to the rest of dopant concentrations. The inclusion of the metallic elements in the TiO2 structure enhances the photocatalytic efficiency of the TiO2 anatase under visible light. TiO2:0.25at%Cu showed the highest EBT degradation yields of 90% color removal, 61% total organic carbon (TOC) reduction, and 87% chemical oxygen demand decrease at 180 min. TiO2:0.25at%Cu and TiO2:0.50at%Fe microspheres retained good degradation efficiency for color and TOC removals even after being reused for three cycles.

Doped MoS2 Polymorph for an Improved Hydrogen Evolution Reaction.

Green hydrogen produced from solar energy could be one of the solutions to the growing energy shortage as non-renewable energy sources are phased out. However, the current catalyst materials used for photocatalytic water splitting (PWS) cannot compete with other renewable technologies when it comes to efficiency and production cost. Transition-metal dichalcogenides, such as molybdenum disulfides (MoS2), have previously proven to have electronic and optical properties that could tackle these challenges. In this work, optical properties, the d-band center, and Gibbs free energy are calculated for seven MoS2 polymorphs using first-principles calculations and density functional theory (DFT) to show that they could be suitable as photocatalysts for PWS. Out of the seven, the two polymorphs 3Ha and 2R1 were shown to have d-band center values closest to the optimal value, while the Gibbs free energy for all seven polymorphs was within 5% of each other. In a previous study, we found that 3Hb had the highest electron mobility among all seven polymorphs and an optimal bandgap for photocatalytic reactions. The 3Hb polymorphs were therefore selected for further study. An in-depth analysis of the enhancement of the electronic properties and the Gibbs free energy through substitutional doping with Al, Co, N, and Ni was carried out. For the very first time, substitutional doping of MoS2 was attempted. We found that replacing one Mo atom with Al, Co, I, N, and Ni lowered the Gibbs free energy by a factor of 10, which would increase the hydrogen evolution reaction of the catalyst. Our study further shows that 3Hb with one S atom replaced with Al, Co, I, N, or Ni is dynamically and mechanically stable, while for 3Hb, replacing one Mo atom with Al and Ni makes the structure stable. Based on the low Gibbs free energy, stability, and electronic bandgap 3Hb, MoS2 doped with Al for one Mo atom emerges as a promising candidate for photocatalytic water splitting.

Solar-Induced Photocatalytic Degradation of Reactive Red and Turquoise Dyes Using a Titanium Oxide/Xanthan Gum Composite

The present study explores the solar-induced photocatalytic degradation of reactive red (RR) and reactive turquoise (RT) dyes in a single system using TiO2 immobilized in xanthan gum (TiO2/XG), synthesized using the sol–gel dip-coating technique for direct precipitation. SEM-EDX, XRD, FTIR, and UV–Vis were used to assess the characteristics of the resulting catalyst. Moreover, the effects of different operating parameters, specifically pH, dye concentration, TiO2/XG concentration, H2O2 concentration, and contact time, were also investigated in a batch photocatalytic reactor. The immobilized TiO2/XG catalyst showed a slight adsorption degradation efficiency and then improved the RR and RT dye degradation activity (92.5 and 90.8% in 120 min) under solar light with a remarkable Langmuir–Hinshelwood pseudo-first-order degradation rate of 0.0183 and 0.0151 min−1, respectively, under optimum conditions of pH 5, dye concentration of 25 mg/L, TiO2/XG concentration of 25 mg/L, H2O2 concentration of 400 mg/L, and reaction time of 120 min. The improved photocatalytic ability was ascribed to the impact of TiO2/XG nanoparticles with a high surface area, and lower band gap energy. Solar light energy has significant potential for addressing energy deficit and water pollution concerns.

Calcination temperatures influence the chemo-resistive gas sensing properties of biogenic zinc oxide nanoparticles with antibacterial activity

This study aimed to optimize Garcinia indica leaf extract mediated biogenic synthesis of antibacterial zinc oxide (ZnO) nanoparticles (NPs) and investigate how the calcination temperatures influence the structural and gas sensing properties of ZnO NPs. To study the effects of calcination temperatures, the optimally biosynthesized ZnO NPs were calcined at different temperatures in the range of 350-500 °C, used for the fabrication of thin films and characterized by various spectroscopic and imaging techniques. Characterization techniques confirmed that ZnO NPs were spherical with crystallite size in the range of 20-30 nm, mesoporous (with slit-shaped pores 1-10 nm), and had low band gap energy. Further, calcination temperatures were found to significantly influence the defect energy levels, porosity, surface roughness, and oxygen vacancies. In addition, the variation in calcination temperature was found to influence the gas response (Rg/Ra), relative response (%), sensitivity, response time, recovery time, and reproducibility. A higher gas response (231) was recorded for a thin film of ZnO NPs calcined at 400 °C than other tested temperatures. The average response and recovery time were 1 s and 218 s respectively for differently calcined ZnO NPs. ZnO NPs calcined at 400 °C were also found to exhibit remarkable antibacterial activity against E. coli and B. subtilis.

Analysis and characterization of opto-electronic properties of iron oxide (Fe2O3) with transition metals (Co, Ni) for the use in the photodetector application

There are several uses for ultraviolet photodetectors, including in the scientific, military, and industrial sectors. In this sense, UV photodetectors must have high responsiveness, be insensitive to visible light, and be inexpensive to produce. For this purpose, we report the development of Co and Ni based iron oxide nanoparticles via the cost effective low temperature sol–gel auto-combustion process. XRD study approves the cubic crystal structure of iron oxide (Fe2O3) with predominant orientation along (311) direction. A sharp and strong peak is obtained at 583 cm−1 and 594 cm−1 for both samples in FT-IR spectra assigned to metal oxide Fe–O network system which approves the formation of iron oxide. Raman spectroscopy analysis reveals the presence of two A1g and five Eg phonon modes in the case of both samples. Absorption study exhibits the strong absorption peaks for the iron oxide sample doped with cobalt and nickel, while poor absorption was noticed from the pure iron oxide nanoparticles. The large and low energy band gap values are found to be 2.77 eV and 1.68 eV for pure Fe2O3 and cobalt and nickel doped Fe2O3 nanoparticles, respectively. Stone and cloud-like shape morphology was observed from SEM analysis. The EDX spectra reveal the presence of essential elements, like Fe and O in the case of pure iron oxide while Fe, O, Co and Ni in the case of transition metals doped iron oxide nanoparticles. The photoluminescence (PL) spectroscopy technique was recorded the luminescent properties which reveals the decrease in PL intensity that confirms the decline in electron–hole recombination. Therefore, I–V characterization analysis reveals that electrical conductivity increases with the addition of metals due to decrease in electron–hole recombination with the co-doping of metals. These modified opto-electronic properties of the developed Fe2O3 by metals co-doping make it suitable candidate for the use in photodetector application.

Optical response of green synthesized thin Cr2O3 films prepared via drop and spin coatings

This study investigated the impact of optical bandgap energy on the optical constants of Cr2O3 thin films, which were prepared via green synthesis method and deposited using drop and spin-coatings at 600, 800, 1000, and 1200 rpm onto Cu substrates. The deposited Cr2O3 thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and UV–VIS-NIR spectroscopy. XRD revealed that the prepared nanocoating surfaces are pure eskolaite Cr2O3 phase. The grain size of the prepared Cr2O3 films decreased from 15 nm to 12 nm for the drop and spin coatings, respectively. The morphology of the drop and spin coated samples showed nanorods, mesospherical, and quasi-spherical shaped nanoparticles, respectively, along with the presence of O and Cr. The bandgap energy increased from 2.35 eV to 2.50 eV, with increasing Spin Coater rotational speeds (RS) from drop to 1200 rpm, respectively. As bandgap energy increase, the carriers' spatial dimension shrinks, resulting in grains smaller than or equal to the exciton's Bohr radius. Thicker film materials tend to have lower bandgap energies due to strain effects, whereas smaller grain sizes tend to have higher bandgap energies. The determined refractive index and extinction coefficient values vary as the bandgap energy varies for all prepared samples. These findings confirmed that differences in bandgap energy affect the refractive index (n) and extinction coefficient (k) of Cr2O3 thin films. These are attributed to quantum confinement, internal scattering, and interference effects of Cr2O3 thin film surfaces.

Novel photo and bio-active greyish-black cotton fabric through air- and nitrogen- carbonized zinc-based MOF for developing durable functional textiles

This study explores the potential of using the carbonization of Zn-based metal-organic frameworks (Zn-MOF-5) under N2 and air to modify zinc oxide (ZnO) nanoparticle for the production of various photo and bio-active greyish-black cotton fabrics. The MOF-derived ZnO under N2 demonstrated a significantly higher specific surface area (259 m2g−1) compared to ZnO (12 m2g−1) and MOF-derived ZnO under air (41.6 m2 g−1). The products were characterized using various techniques, including FTIR, XRD, XPS, FE-SEM, TEM, HRTEM, TGA, DLS, and EDS. The tensile strength and dye degradation properties of the treated fabrics were also investigated. The results indicate that the high dye degradation capability of MOF-derived ZnO under N2 is likely due to the lower ZnO band gap energy and improvement in electron-hole pair stability. Additionally, the antibacterial activities of the treated fabrics against Staphylococcus and Pseudomonas aeruginosa were investigated. The cytotoxicity of the fabrics was studied on human fibroblast cell lines using an MTT assay. The study findings demonstrate that the cotton fabric covered with carbonized Zn-MOF under N2 is human-cell compatible while showing high antibacterial activities and stability against washing, highlighting its potential for use in developing functional textiles with enhanced properties.

Optimized geometric structure of Zn-BTC/POAP and Fe-BTC/POAP systems as electroactive materials in pseudocapacitors

In this work, Fe(II)-based metal organic framework (MOF), Zn-based MOF and hybrid poly orthoaminophenol/MOF composite were synthesized via a chemical method. Synthesized composite films have been characterized by conventional electrochemical methods and computational approach. The computational results show that both Zn-BTC and Fe-BTC interact well with 3POAP. Meanwhile, the adsorption energy of 3POAP on Fe-BTC is 2.03 eV higher than that of Zn-BTC. Therefore, it can be mentioned that the high adsorption energy of conductive polymer POAP on Fe-BTC compared to Zn-BTC has led to its better performance as the electrode of supercapacitors and these findings confirm the electrochemical results. It was found that in Zn-BTC/3POAP and Fe-BTC/3POAP systems the charge is transferred from the 3POAP to the MOFs. The results showed that the charge transfer from 3POAP to Fe-BTC is more than Zn-BTC which is a confirmation of the higher adsorption of 3POAP on Fe-BTC. The 3D periodic structure of Fe-BTC is generated by binuclear Fe(II) paddlewheel building units (PBUs) connected via the 1,3,5-benzenetricarboxylate organic ligands. Also, the adsorption energy of 3POAP on Fe2(PhCOO)4 and Zn2(PhCOO)4 was calculated using supermolecular approach. These results are compatible with the adsorption energy obtained from the periodic calculations, so that the adsorption of Fe structure was more than that of Zn. The Fe2(PhCOO)4…3POAP structure has the lowest band gap energy, so it can be concluded that the better adsorption of 3POAP on Fe-BTC not only results in higher adsorption energy, but also better electrical conductivity than the Zn-BTC. Computational results are in agreement with electrochemical results.

Synthesis of solar-driven Cu-doped graphitic carbon nitride photocatalyst for enhanced removal of caffeine in wastewater

Caffeine (CaF), a widely consumed compound, has been associated with various harmful effects on human health, including metabolic, cardiovascular disease, and reproductive disorders. Moreover, it poses a signifincant threat to organisms and aquatic ecosystems, leading to water pollution concerns. Therefore, the removal of CaF from wastewater is crucial for mitigating water pollution and minimizing its detrimental impacts on both humans and the environment. In this study, a solar-driven Cu-doped graphitic carbon nitride (Cu/CN) photocatalyst was synthesized and evaluated for its effectiveness in oxidizing CaF in wastewater. The Cu/CN photocatalyst, with a low band gap energy of 2.58eV, exhibited superior performance in degrading CaF compared to pure graphitic carbon nitride (CN). Under solar light irradiation, CuCN achieved a remarkable CaF degradation efficiency of 98.7% CaF, surpassing CN's efficiency of 74.5% by 24.2%. The synthesized Cu/CN photocatalyst demonstrated excellent removal capability, achieving a removal rate of over 88% for CaF in wastewater. Moreover, the reusability test showed that Cu/CN could be successfully reused up to five cycles maintaining a high removal efficiency of 74% for CaF in the fifth cycle. Additionally, the study elucidated the oxidation mechanism of CaF using solar-driven Cu/CN photocatalyst and highlighted the environmental implications of the process.

Quantum dots decorated photoanodes in bioelectrochemical fuel cells: Enhanced electricity generation using green algae.

The power performance of the bio-electrochemical fuel cells (BEFCs) depends mainly on the energy harvesting ability of the anode material. The anode materials with low bandgap energy and high electrochemical stability are highly desirable in the BEFCs. To address this issue, a novel anode is designed using indium tin oxide (ITO) modified by chromium oxide quantum dots (CQDs). The CQDs were synthesized using facile and advanced pulsed laser ablation in liquid (PLAL) technique. The combination of ITO and CQDs improved the optical properties of the photoanode by exhibiting a broad range of absorption in the visible to UV region. A systematic study has been performed to optimize the amount of CQDs and green Algae (Alg) film grown using the drop casting method. Chlorophyll (a, b, and total) content of algal cultures (with different concentrations) were optimized to investigate the power generation performance of each cell. The BEFC cell (ITO/Alg10/Cr3//Carbon) with optimized amounts of Alg and CQDs demonstrated enhanced photocurrent generation of 120 mA cm-2 at a photo-generated potential of 24.6 V m-2 . The same device exhibited a maximum power density of 7 W m-2 under continuous light illumination. The device also maintained 98% of its initial performance after 30 repeated cycles of light on-off measurements.

SrMn1-xFexO3-δ (x = 0–1) black ceramic pigment: Synthesis, color properties, and application

In this work, SrMn1-xFexO3-δ (x = 0–1) black ceramic pigments were synthesized by the solid-state method. The research explores the influence of calcination temperature and iron ion doping on the color properties of the pigments. Furthermore, the potential applications of SrMn1-xFexO3-δ pigments in ceramic glaze and heat-absorbing materials are also discussed. The findings reveal that the synthesized SrMnO3 pigment exhibits the lowest L*-value (22.30) at 1100 °C, although it displays a slight blue hue. To optimize the color properties of the SrMnO3 pigment, iron ion doping is employed. When the doping level of iron ions is 50 mol.% (i.e., x = 0.5), the L*-value of the SrMn0.5Fe0.5O3-δ pigment calcined at 1000 °C significantly decreases to 19.77, while the a*- and b*-values approach 0, resulting in a pure black color. This is attributed to the high surface roughness, low band gap energy, and substantial oxygen vacancies present in the SrMn0.5Fe0.5O3-δ pigment. The tinting mechanism of the SrMn1-xFexO3-δ pigment in the ceramic glaze is classified as "ion tinting", wherein the glaze color relies on the concentrations of Mn and Fe ions. When the pigment content reaches 36 wt%, the L*-value of the glaze drops to 4.94, showing a deep black shade. Additionally, the SrMn0.5Fe0.5O3-δ pigment exhibits excellent sunlight absorption capabilities, with a near-infrared reflectance (R*) of only 5.04%. This research presents a black ceramic pigment with various advantages, such as simplified processing, affordability, environmental friendliness, and exceptional color performance.

Study on crystal structure, electrical and magnetic properties of LaFe xCo1-xO3 prepared by sol-gel method

Lanthanum Ferri-cobaltates magnetic semiconducting materials are very interesting materials and they have a wide range of applications. Electrical and magnetic transport in such materials and their correlation with crystal structure have been investigated. All synthesized samples based on the sol-gel method are in the nanocrystalline range (27–38 nm) with the rhombohedral crystal system. The low electronic density was calculated from XRD patterns and the obtained results showed that a slight variation in electronic density is noted as a result of small cobalt substitution by iron in LaFe0.8Co0.2O3 and LaFe0.5Co0.5O3. A drastic increase in the electronic density was observed in LaFe0.2Co0.8O3 and again a decrease in the value of the electronic density in LaCoO3. IR spectra confirmed the formation of the proposed Perovskite crystal symmetry. Although the dc conductivity of all samples was small, we found a difference as a result of replacing iron with cobalt. The mechanism of electronic transfer in LaFexCo1-xO3 is mainly due to the electrons hopping between both Fe3+↔Fe2+ and Co3+↔Co2+ ions. Electrical measurements showed the semiconducting behavior of all samples. The optical properties studied by UV–Vis diffuse reflectance showed a large change in the optical energy gap with increasing Fe ions. All samples have a low energy band gap. The minimum Hci was 67G and the maximum was 715G as a result of doping. Magnetic hysteresis at room temperature showed antiferromagnetic order with weak ferromagnetism (canted antiferromagnetic order) enhanced with Fe content. The multi-domain grains appeared in La FexCo1-xO3 because the squareness ratio (Mr/Ms) in our case is in the range between 0.0 and 0.25.

Reduced graphene oxide-functionalized zinc oxide nanorods as promising nanocomposites for white light emitting diodes and reliable UV photodetection devices

We present a breakthrough in the development of novel nanocomposites based on reduced graphene oxide (RGO)-functionalized zinc oxide (ZnO) nanorods that hold exceptional promise for their use in white light emitting diodes (LEDs) and reliable UV photodetection. The nanorods had a pristine hexagonal wurtzite structure, as confirmed by XRD analysis. SEM images revealed sandwich-like nanocomposites with ZnO nanorods coated in reduced graphene oxide and embedded between two layers of RGO. The study also confirmed the hybridization and interactions between the layers using Raman measurements. The resulting nanocomposites displayed a lower band gap energy than ZnO and exhibited unique photoluminescence spectra with a white PL light. The photodetector based on RGO/ZnO/RGO sandwich structures demonstrated exceptional photoresponse, with higher photocurrent under UV illumination, making it highly promising for a wide range of optoelectronic applications. Overall, this study offers a novel and powerful approach to create nanocomposite structures with enhanced optical characteristics.

Studies of structural, dielectric, and optical properties of CuCoFeO4 spinel for high frequency, microwave, and optoelectronic applications

In this study, we synthesized by the sol-gel method the CuCoFeO4 spinel and studied its structural, dielectric, and optical properties. The sample exhibits a regular cubic spinel structure (Fd3¯m space group). Semiconductor behavior with the CBH model was observed from the variation in electrical conductivity as a function of frequency and temperature. Summerfield scaling merges conductivity isotherms into a single master curve. Non-Debye relaxation is shown in the electric modulus of the prepared composition. The impedance spectra indicate the effects of both grain and grain boundary contributions on electrical properties. The impedance analysis is presented with electrical processes modeling in the sample. This is done using an equivalent circuit model comprising a parallel RC circuit for grains and grain boundaries. The obtained simulated results agree with the measured results. Maxwell-interfacial Wagner's polarization theory was used to explain dielectric constant change. The synthesized material exhibits low dielectric constants and dielectric losses at higher frequencies, as well as high electrical resistivity. These properties make CuCoFeO4 spinel a suitable candidate for high-frequency applications and microwave absorption devices. Moreover, CuCoFeO4 spinel presents low band gap energy, making it a suitable material for visible-light absorption.

Performance evaluation of PdO/ CuO TiO2 photocatalytic membrane on ceramic support for removing pharmaceutical compounds from water.

This study investigated photocatalytic degradation of pharmaceutical compound using CuO or PdO-TiO2 membrane. The synthesized membranes were characterized by some techniques including X-ray powder diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR). The structural properties confirmed that the photocatalytic membranes were successfully prepared on ceramic supports. The PdO-TiO2 and CuO-TiO2 membranes were employed as photocatalytic membranes to degrade metronidazole (MNZ) and diphenhydramine (DPH) in aqueous solutions, respectively. Some parameters affecting the photocatalytic reaction such as pH, initial concentration, and light source were also investigated. The maximum degradation for both pharmaceutical compounds was obtained at basic pH (pH = 10), low initial concentration (C0 = 10ppm) under UV irradiation. At high transmembrane pressure (ΔP = 3bar), the flow rate across the membrane increased up 0.0078 and 0.0082cc/s.cm2 for CuO-TiO2 and PdO-TiO2 photocatalytic membrane respectively while not affected on degradation efficiency (DE). At the same condition operation (C0 = 10ppm, pH = 10, ΔP = 2bar under UV irradiation), the MNZ and DPH degradation of the PdO-TiO2 membrane was 94 and 95% respectively that relatively higher than the CuO-TiO2 membrane. It is probably due to the lower energy band gap of PdO-TiO2 (2.5eV) than CuO-TiO2 (2.7eV). The membrane stability tests confirmed the high performance of the prepared membranes.

Optical monitoring of DC/RF plasma sputtering for copper oxide film growth at low temperature

DC/RF plasma sputtering process for the growth of copper oxide thin film was studied by optical emission spectroscopy. The films were produced by a balanced magnetron sputtering system nearly at room temperature. The influence of applied power in DC and RF mode and Ar/O2 flow ratio on the film properties was investigated as well as their relationship to the plasma species and the main chemical reactions during the film growth. It was found that the concentration of active species in the plasma and their abundance ratio is very effective in the reactions related to the film growth process and the properties of the deposited film. It was shown that copper oxide film with CuO phase owing low energy band gap can be synthesized at low temperatures by controlling the ionization rate, the energy of the active species, the film growth rate, and finally the relative concentration of copper to oxygen species in the plasma. CuO thin films (Eg=1.28 eV) were achieved in DC mode at the lowest applied power (50 W) and in the lowest Ar/O2 flow ratio (2/1). This oxide phase was also observed for two both the synthesized films in RF mode, at 50 W (Eg=1.39 eV) and 100 W (Eg=1.23 eV) in an Ar/O2 flow ratio of 2/1.

Synergistic photodegradation of methylene blue by Sm doped Fe2O3 photocatalyst under sunlight

• Fe 2 O 3 , Sm 2 O 3 and Sm doped Fe 2 O 3 photocatalysts synthesized via sol-gel route • Sm-doped material showed good surface area of 1327 cm 2 /g • The doped materials showed excellent photodegration of 99.8% • The higher efficiency of the catalyst is owing to efficient charge separation/transportation. The growing population led to an increase in water contamination, which urged researchers to develop an efficient, eco-friendly, and safe catalyst to remove these pollutants from water bodies. Herein the present study, the Sm-doped Fe 2 O 3 photocatalyst was developed through a low-cost and facile sol-gel route to degrade methylene blue (MB) under sunlight. Various characterizations of the photocatalyst were performed by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), photoluminescence (PL), and UV–vis spectrometry, current-voltage measurements (IV), and electrochemical impedance spectroscopy (EIS). The XRD confirmed the successful doping of Sm in Fe 2 O 3 lattices. Remarkably, the adsorption were 14%, 10%, 34%, photo-reduction efficiencies were 78.2%, 79.1%, 65.8%, while complete degradation of dyes were 91.2, 89.1 and 99.8% for Fe 3 O 3 , Sm 2 O 3 and Sm-doped Fe 2 O 3 , respectively, against methylene blue dye after 1.0 h under sunlight illumination. Moreover, the enhanced photocatalytic performance of the doped catalyst was found to be due to the structural variation, lower energy bandgap, hindered recombination, and the efficient charge carriers separation/transportation at the surface. The effective synergistic photocatalytic performance proved its potential in water remediation.

S–CdIn2S4: A novel near-infrared emitter triggered by low potential for constructing a dual-mode immunosensing platform

CdIn2S4 is an interesting ternary metal sulfide whose narrow band gap and tunable optical properties offer new opportunities for the development of novel ECL emitters. Here, we use a simple hydrothermal synthesis to obtain hollow spindle CdIn2S4 (S–CIS), which exhibits strong near-infrared electrochemiluminescence (ECL) emission with K2S2O8 as a coreactant at a low excitation potential (−1.3 V), which is encouraging. The lower excitation potential of S–CIS is probably due to the low band gap energy, which makes the excitation potential positively shift. This lower excitation potential reduces the side-reactions caused by high voltages, effectively avoiding irreversible damage to biomolecules, and protecting the biological activity of antigens and antibodides. In this work, new features of S–CIS in ECL studies are also presented, demonstrating that the ECL emission mechanism of S–CIS is generated by surface state transitions and that S–CIS exhibits excellent near-infrared (NIR) characteristics. Importantly, we introduced S–CIS into electrochemical impedance spectroscopy (EIS) and ECL to the construct a dual-mode sensing platform to achieve AFP detection. The two models with intrinsic reference calibration and high accuracy showed outstanding analytical performance in AFP detection. The detection limits were 0.862 pg mL−1 and 16.8 fg mL−1, respectively. This study demonstrates the key role and great application potential of S–CIS as a novel NIR emitter with easy preparation, low cost and great performance in the development of a simple, efficient and ultrasensitive dual-mode response sensing platform for early clinical use.