UV Vis Diffuse Reflectance Spectroscopy Research Articles

Synthesis of Ag/ZnO/BiOCl Composite Material and Its Photodegradation Performance on Ciprofloxacin

This study focuses on synthesizing a composite material of Ag/ZnO/BiOCl using Ag, ZnO, and BiOCl as raw materials. The material was prepared by loading Ag and BiOCl onto ZnO nanofilms, aiming to enhance the photocatalytic degradation of ciprofloxacin (CIP). Optimization of the photocatalytic degradation process through single-factor experiments revealed that under conditions of an initial CIP pH of 9, an Ag/ZnO/BiOCl dosage of 1 g/L, and an initial CIP concentration of 5 mg/L the conversion efficiency of CIP reached 98.79% after 150 min of exposure to a 250 W xenon lamp simulating sunlight. Furthermore, the composite material maintained a conversion efficiency of 86.17% for CIP even after five cycles of reuse, demonstrating its excellent stability. The optical properties, elemental composition, valence state, crystallinity, and morphology of the samples were analyzed using techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), UV–visible diffuse reflectance spectroscopy (UV-vis DRS), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicate that the introduction of Ag expanded the light response range of ZnO, while the addition of BiOCl improved the separation efficiency of electron–hole pairs in the composite nanomaterial. The photocatalytic mechanism was further elucidated through radical scavenging experiments, confirming that ·OH and h+ are the main active species in the degradation process.

Sonochemically Synthesized Bismuth Oxyiodide Nanocrystal for Wastewater Remediation through Visible‐Light Photocatalysis

AbstractIt has been demonstrated that bismuth oxyhalides [BiOX (X = Cl, Br, and I)] nano‐crystals can efficiently behave as photocatalysts both under visible light and UV light. Different types of dyes, phenols, etc. can be degraded by bismuth oxyhalides materials efficiently, for the purification of wastewater. The raw materials used in the synthesis of bismuth oxyiodide (BiOI) are pure Bi2O3, halide salt, and capping agent (poly‐vinyl‐pyrrolidone). A variety of characterization techniques are used to characterize the as‐synthesized samples, including X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Vis diffuse reflection spectroscopy (UV–Vis DRS), photoluminescence (PL), Mott–Schottky, field emission scanning electron microscopy (FESEM), energy dispersive X‐ray spectroscopy (EDX), and high resolution transmission electron microscopic (HRTEM), etc. A potential application in environmental remediation is achieved through 95.25% degradation of organic Rhodamine B (RhB) dye within 100 min using the synthesized materials under visible light irradiation.

Synthesis, crystal structure, thermal stability, and photovoltaic properties of organic-inorganic hybridized copper-based perovskite single crystals modulated by organics

Organic-inorganic hybridized perovskite have excellent photovoltaic properties, especially Pb-based organic-inorganic perovskite polycrystalline thin films based on Pb-based organic-inorganic perovskite have achieved high power conversion efficiency, but the polycrystalline materials have a large number of grain boundaries and defects, which are susceptible to the influence of water and oxygen, leading to structural degradation, poor stability, high toxicity and slow degradation, which are not friendly to the environment. Therefore, in this paper, two copper-based organic-inorganic hybrid perovskite single crystals (C6H9N2)2CuCl4 and (C6H18N2)2Cu2Cl8 were synthesized by using the method of organic modulation, and were investigated by single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis, and UV–vis diffuse reflectance spectroscopy. The samples were analyzed in detail for crystal structure, chemical groups, bond characterization, optical and thermal stability. The results show that (C6H9N2)2CuCl4 and (C6H18N2)2Cu2Cl8 single crystals belong to the C2/c space group of the monoclinic crystal system and the P-1 space group of the triclinic crystal system, respectively. The optical band gap of (C6H9N2)2CuCl4 is 2.45 eV, which is stable up to 179 °C, and that of (C6H18N2)2Cu2Cl8 is 2.47 eV, which is stable up to 163 °C. The thermal stability of the crystals can be regulated by changing the organic cation in the A-site, but the optical band gap of the crystals cannot be regulated significantly.

Graphite/carbon-doped TiO2 nanocomposite synthesized by ultrasound for the degradation of diclofenac.

Graphite/C-doped TiO2 nanocomposite was synthesized at room temperature using a simple, impressive, and indirect sonication (20kHz) by the cup horn system. Tetrabutyltitanate as the precursor of titanium and graphite (G) as the carbon source was used in the preparation of nanocomposite as a photocatalyst. The molar ratio of G/TiO2 as a key parameter was investigated in the synthesis of G/C-doped TiO2. The obtained materials were widely characterized using XRD, SEM, TEM, FTIR, XPS, and UV-Vis diffuse reflectance techniques. The UV-Vis diffuse reflectance spectroscopy results showed that the edge of light absorption of nanocomposite was distinctly red-shifted to the visible area via carbon doping. The XPS outcomes acknowledged the existence of the C, Ti, and O in the photocatalyst. The composite showed an enhancement in the dissociation efficiency of photoinduced charge carriers through the doping process. The photocatalytic activity of the synthesized nanocomposite was checked with diclofenac (DCF) as a pharmaceutical contaminant. The results displayed that G/C-doped TiO2 represented better photocatalytic performance for DCF than TiO2. This was due to the excellent crystallization, intense absorption of visible light, and the impressive separation of photoinduced charge carriers. Various active species such as •OH, •O2¯, h+, and H2O2 play a role in the degradation of DFC. Therefore, different scavengers were used and the role of each one in degradation was investigated. According to the obtained results, •O2¯ radical showed a major role in the photocatalytic process. This work not only proposes a deep insight into the photosensitization-like mechanism by using G-based materials but also develops new photocatalysts for the removal of emerging organic pollutants from waters using sunlight as available cheap energy.

Influence of visible light LEDs modulation techniques on photocatalytic degradation of ceftriaxone in a flat plate reactor

In this paper, the effect of light modulation on photocatalytic ceftriaxone (CEF) degradation in aqueous solution was investigated. The experimental set-up consisted of a fixed bed photocatalytic reactor with a flat plate geometry and visible LEDs for irradiation. Fe-N-codoped TiO2 photocatalyst was immobilized on a polystyrene plate (PS) by solvent casting method to achieve a structured photocatalyst (Fe-N-TiO2/PS), which was loaded in the photoreactor. Raman and UV–Vis diffuse reflectance spectroscopy confirmed the presence of Fe-N-TiO2 on the PS surface and its uniform distribution on the polymer support. Various LEDs dimming techniques were tested with fixed and variable duty-cycle values. In particular, the following modulations were used: fixed duty-cycle (FD), sinusoidal variable duty-cycle (S-VD), triangular variable duty-cycle (T-VD), square wave variable duty-cycle (SW-VD), saw-tooth variable duty-cycle (ST-VD), pulse variable duty-cycle (P-VD), and pseudo-sinusoidal variable duty-cycle (PS-VD). The optimal light modulation was the S-VD, with an average fed current between 25 and 75 mA and a period of 30 s. Indeed, by using S-VD modulation, the highest value of the apparent CEF degradation kinetic constant (resulting 0.0082 min−1) and the highest total organic carbon (TOC) removal (70 %) were achieved. By comparing the electric energy consumption (EE/O) with S-VD modulation used in this work with those found in other literature studies dealing with the photocatalytic ceftriaxone degradation, a significant decrease of EE/O was evidenced. Moreover, toxicity test showed that the photocatalytic treatment allowed to significantly reduce the toxicity of CEF solution when compared to untreated effluent.

Thermotropic Structure Phase Transitions and Two Types of Thermochromic Behaviors in a Bromoargentate Cluster [Pr-dabco]2Ag4Br6.

Organic-inorganic silver halide hybrids show abundant phase transitions and thermochromism. However, it is very rare that silver halides exhibit thermochromism related to thermotropic structure phase transition. Herein, a bromoargentate hybrid, [Pr-dabco]2Ag4Br6 (1) (Pr-dabco+ = 1-propyl-1,4-diazabicyclo-[2.2.2]octan-1-ium), with tetranuclear [Ag4Br6]2- clusters was prepared and characterized by microanalysis, ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, and thermogravimetric (TG) and differential scanning calorimetry (DSC) techniques. Interestingly, 1 undergoes an irreversible structure phase transition at ∼436 K in the first heating process, which is accompanied by an abrupt color change from colorless to yellow; however, a reversible color change between pale yellow and yellow is observed in the next heating-cooling cycles. Notably, DSC measurement revealed that a reversible phase transition is associated with the change in color between pale yellow and yellow, while the powder X-ray diffraction (PXRD) patterns corresponding to pale yellow and yellow phases are quite similar to each other. These observations demonstrate that thermochromism in the next heating-cooling runs is associated with a reversible structure phase transition, which perhaps concerns the disorder-order transformation of alkyl chains in the cationic ligand [Pr-dabco]+, and relevant to the anharmonic fluctuations of the Ag-Br and Ag-N bonds, a strong electron-phonon coupling effect is seen within the bromoargentate cluster.

Efficient photocatalytic degradation of ciprofloxacin by doped Bi4O5I2 with Gd3+ as an electron trap: Gd3+ substitutes Bi3+ in the lattice

Gd3+-doped Bi4O5I2 with a flower-like structure has been successfully prepared for the first time using a one-step hydrothermal method. The effect of different doping amounts on the photodegradation properties has been investigated. The total removal of ciprofloxacin (CIP) by 3 % Gd–Bi4O5I2 (molar atomic ratio of Gd to Bi = 0.03:1) under visible light irradiation was 94.50 % (within 120 min). The reaction rate constant was 6.3 times higher than that of pure Bi4O5I2. In complex water containing humic acid (HA) and various anions, 3 % Gd–Bi4O5I2 maintained a high total removal rate for CIP. UV–Vis diffuse reflectance spectroscopy and electrochemical tests have shown that doping Gd3+ not only extends the photoresponse range, but also reduces the photonic band gap width. Gd3+ ions act as electron traps to trap excited electrons and promote the separation and migration efficiency of photogenerated electron-hole pairs, improving the performance of Gd–Bi4O5I2 composites for the photocatalytic degradation of CIP.

Carbon Dot-Titanium Dioxide (CD/TiO2) Nanocomposites: Reusable Photocatalyst for Sustainable H2 Production via Photoreforming of Green Organic Compounds

The present work focuses on TiO2 modification with carbon dots (CDs) using a hydrothermal process, which results in the synthesis of CD/TiO2 nanocomposite photocatalysts characterized by exceptional optoelectronic properties. The structural and physicochemical properties of the obtained nanocomposites, which contained varying amounts of CDs, were precisely assessed. HR-TEM analysis showed that the prepared nanocomposites consisted of rod-shaped TiO2 nanoparticles and CDs well-dispersed on their surface. The optical properties of the nanocomposites were studied using UV–vis diffuse reflectance spectroscopy. All CD/TiO2 samples presented decreased energy gap values compared with bare TiO2 samples; the band gap was further decreased as the CD concentration rose. Electrochemical measurements revealed that the presence of CDs improved the photocurrent response of the TiO2, presumably due to enhanced charge separation and decreased recombination. The synthesized nanomaterials were used as photocatalysts to produce hydrogen via the photoreforming of ethanol and glycerol green organic compounds, under 1-sun illumination. The photocatalytic experiments confirmed that the optimum loading of CDs corresponded to a percentage of 3% (w/w). Ethanol photoreforming led to a H2 production rate of 1.7 μmol∙min−1, while in the case of the glycerol sacrificial agent, the corresponding rate was determined to be 1.1 μmol∙min−1. The recyclability study revealed that the photocatalyst exhibited consistent stability during its reuse for hydrogen production in the presence of both ethanol and glycerol.

Enhanced photocatalytic activity of SnO2/g-C3N4 nanocomposite synthesized using sonochemistry method

The SnO2/g-C3N4 nanocomposite materials were successfully synthesized via the solid reaction and sonochemistry methods. The properties of the obtained product were investigated using several methods: X-ray diffraction, UV-vis diffuse reflectance spectroscopy, and Scanning electron microscope. The photocatalytic properties of the samples were evaluated through the photodegradation of Rhodamine B solution. The results demonstrate that the SnO2/g-C3N4 prepared by the sonochemistry method exhibits higher photocatalytic activity than that prepared by the solid reaction method. This enhanced photocatalytic activity is attributed to the formation of heterostructures between SnO2 and g-C3N4 materials, resulting in the efficient separation of photo-generated electron-hole pairs. Furthermore, the nanocomposite exhibits a larger specific surface area compared to the product obtained through the solid reaction method.

Green Fabrication of ZnO Nanoparticles and ZnO/rGO Nanocomposites from Algerian Date Syrup Extract: Synthesis, Characterization, and Augmented Photocatalytic Efficiency in Methylene Blue Degradation

This innovative article provides a detailed description of the successful biosynthesis of zinc nanoparticles (ZnO-NPs) using an aqueous extract of Algerian Date Syrup, also known as molasses. A meticulous process was carried out to determine the optimal calcination temperature for ZnO-NPs, a crucial step in the preparation of these nanoparticles. The study was further extended by creating ZnO/rGOx nanocomposites through a hydrothermal method, varying the concentrations of reduced graphene oxide (rGO) at 5%, 10%, and 15%. The characteristics of the nanocomposites were thoroughly explored, encompassing chemical, optical, and morphological aspects, using sophisticated analysis techniques such as scanning electron microscopy (SEM), UV-visible diffuse reflectance spectroscopy (UV DRS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). These analyses provided an in-depth understanding of the structure and properties of the nanocomposites. The centerpiece of this study is the evaluation of the photocatalytic degradation capacity of ZnO-NPs and ZnO/rGOx nanocomposites. These materials have demonstrated their ability to act as cost-effective and environmentally friendly photocatalysts for wastewater treatment. Experiments on methylene blue degradation under UV irradiation were conducted, yielding impressive results: a degradation efficiency of 86.6% was achieved in 140 min using 1 g/L of ZnO-NPs, and this rate reached 100% with the ZnO/rGO catalyst in the same time frame, highlighting its superiority as a photocatalyst. Furthermore, this study examined the variables affecting the photocatalysis experiment, including the solution’s pH and the amount of catalyst. The results revealed that the ZnO/rGO photocatalyst reached its optimal efficiency under neutral pH conditions and at a concentration of 1 g/L, providing crucial information for practical use of these materials. This enriched article highlights the promising potential of ZnO-NPs and ZnO/rGOx nanocomposites as efficient photocatalysts for methylene blue degradation, paving the way for significant environmental applications in wastewater treatment.

Solar irradiation driven catalytic dye degradation by novel biosynthesized zinc oxide nanoparticles (ZnO–NPs) from Barleria mysorensis: Kinetics, reusability and mineralization studies

During the study, Barleria mysorensis B.Heyne ex Roth was selected for biosynthesizing zinc oxide nanoparticles (ZnONPs) and evaluating its photocatalytic properties. The structural and morphological characterization of the synthesized particles were performed by UV–Vis diffusion reflectance spectroscopy (UV–Vis DRS), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS), Fourier-Transform Infrared (FT-IR) spectroscopy and Braunauer–Emmett–Teller (BET) studies. The results indicate high-quality ZnONPs of 34.36 nm crystallite size with 92.32 % elemental purity (ZnO) and an energy band gap of 3.18 eV. According to the BET study, the synthesized particles had a surface area of 21.626 m2 g–1 with 0.001354 cm3g−1 (p/po=0.908) total pore volume of 0.001354 cm3g−1 (p/po=0.908) and 7.34 nm of mean pore diameter. The electron resonance spectroscopy (ESR) revealed that upon interaction of ZnONPs revealed the formation superoxide radical ions. The photocatalytic degradation of methylene blue (MB) dye using the synthesized nanoparticles revealed a degradation efficiency of approximately 91.32 % within 120 min of exposure at a rate constant of 18.34 × 10−3 min−1 and it was also noted that the dye degradation process followed pseudo-first-order kinetics. Besides, reusability and structural stability studies of ZnONPs as photocatalysts revealed a stable performance up to five cycles. In addition, mineralization studies revealed a steady decrease in COD and TOC content with an increase in reaction time, indicating an improvement in mineralization. In conclusion, biosynthesized ZnONPs get rid of the dye and lower the solution's COD and TOC, ensuring that the dye in question breaks down and non-toxic end products are made.

The influence of Nd3+ doping on the structural, optical, magnetic, and dielectric characteristics of nanoscale hexagonal wurtzite type ZnO

Nd3+ doped ZnO nanoparticles (NPs) Zn1−xNdxO (x = 0, 0.01, 0.03, and 0.05) were successfully synthesized via simple co-precipitation method. To extract precise crystallite size and lattice strain from the X-Ray Diffraction (XRD) pattern, Halder-Wagner method was employed. High Resolution Transmission Electron Microscopy (HRTEM) analysis clearly substantiates the NPs formation.The band gap variation in the doped samples in comparison with the pristine sample is extracted from UV–Vis diffuse reflection spectroscopy. The decrease in Photo-luminance (PL) intensity is observed to be significant for enhanced photocatalytic applications. At room temperature (RT), all Nd3+doped ZnO samples exhibit a distinct hysteretic loop. The initial magnetization graph and M-T curve fitted by the modified Brillouin function and combination of spin wave and Curie-Weiss law respectively. The well-fittings indicate the co-existence of paramagnetic (PM) and ferromagnetic (FM) phases in the doped sample, and the quantitative contribution to each phase is also extracted. Significantly high dielectric constant and low ac conductivity at a low frequency region support the presence of large dipolar effect-induced frequency-dependent short-range conductivity in these pristine and Nd3+ doped ZnO samples.

Composition dependent variation in structural, morphological, optical and magnetic properties of biogenic CuO/NiO mixed oxides nanoparticles

A series of CuO/NiO nanoparticles with different Cu and Ni precursor concentrations represented as N12 (1:2), N22 (1:1) and N21 (2:1) (Cu2+:Ni2+) were produced by modified green solution combustion route using Moringa oleifera leaves extract as an organic fuel. The prepared CuO/NiO nanoparticles were analytically characterized using UV-Vis diffuse reflectance spectroscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and vibrating sample magnetometry. Morphological studies showed uniform and nearly monodisperse nanoparticles having average grain size of 34 nm for N22 nanoparticles while the N12 and N21 compositions showed uniform nanoparticles with the grain size of 12 nm and 22 nm respectively. The existence of CuO and NiO phases in nanoparticles was verified by XPS analysis. N12, N22 and N21 had band gaps in the range of 2.19–2.49 eV and specific surface area in the range of 4.92–11.2 m2/g. The susceptibility vs. temperature plots for mixed oxides nanoparticles showed distinct magnetic behaviour for different ratio. The coercivity and saturation magnetization reached a maximum value for N22 (130 Oe and 0.133 emu/g). These biogenic nanoparticles could be a strong choice for biological applications due to their soft magnetic behaviour and biocompatibility.

Optimization on the heterogeneous photocatalytic degradation of Azorubine E122 dye using nanocomposite via CuO nanoparticles with sodium mordenite

The study details the development and characterization of a novel photocatalyst, a combination of cupric oxide nanoparticles and sodium mordenite (CuO NPs/NaMOR), designed for the degradation of Azorubine (E122) dye in water under air conditions using sunlight irradiation. Various analytical techniques, including Powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS), and Brunauer–Emmett–Teller (BET) were employed for thorough photocatalyst characterization. The resulting photocatalyst exhibits noteworthy characteristics, such as a large specific surface area of 129.22 m2/g, pore volume is 0.46 cm3/g, an average pore radius of 1.450 nm, and an overall pore size of 0.123 cm3/g. An optical band gap energy of 1.78 eV. Achieving a maximum degradation efficiency of 91 % for E122 dye after 120 min, the photocatalyst follows first-order Langmuir kinetics with a rate constant of 0.035 min−1. Radical trapping tests support the involvement of radicals like •OH and •O2− in the photocatalytic degradation process. Additionally, the computed potential energies of the valence and conduction bands were found to be 0.42 and 2.20 eV, respectively. The photocatalyst demonstrated remarkable stability, registering degradation efficiencies of 91.0 %, 89.9 %, 88.8 %, 87.5 and 86.0 % across five reuse cycles. Photoluminescence experiments using terephthalic acid confirmed the generation of •OH free radicals during irradiation. Overall, the CuO NPs/NaMOR photocatalyst emerges as a promising candidate for solar-driven environmental remediation applications, owing to its effectiveness, stability, and reusability. The photocatalytic degradation was enhanced utilizing Box-Behnken design.

Synthesis and characterization of porous and photocatalytic geopolymers based on natural clay: Enhanced properties and efficient Rhodamine B decomposition

In this work, the incorporation of anatase TiO2 semiconductor in the geopolymer matrix as catalytic materials has been studied. The most noteworthy results obtained from the synthesis of a novel TiO2/geopolymer nanocomposite as an effective ecological catalyst with high thermal stability and significant porosity is presented. The porous and photocatalytic geopolymers based natural clay rich in pyrophyllite and kaolinite minerals were prepared by simple method, the geopolymerization reaction was able to successfully load TiO2 nanoparticles into the geopolymer surface. Furthermore, the results indicate that the prepared catalyst achieved the best performance to degrade Rhodamine B (RhB) molecules present in aqueous solution under UV light irradiation. The geopolymer matrix proved to be a reusable support for TiO2 nanoparticles during the photocatalytic process, efficiently facilitating the separation of photogenerated charges. Finally, the physicochemical and morphological properties of the samples was characterized by several techniques, namely X-ray Fluorescence (XRF), X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Thermogravimetric and Differential Thermal Analysis (TGA/DTA), N2 adsorption/desorption isotherm analysis (BET and BJH methods), UV–Vis Diffuse Reflectance Spectroscopy (DRS), Scanning Electron Microscopy (SEM) coupled to an Energy Dispersive X-ray Spectroscopy (EDS) analyzer and Transmission Electron Microscopy (TEM).

Superparamagnetic Fe3O4/In(OH)3 nanocomposite as a functional photocatalyst for the treatment of dyes and microbes under UVC

We report herein an improved method to produce a superparamagnetic Fe3O4/In(OH)3 nanocomposite (SPIDIN) at 25 °C in water by directly reducing FeCl3 with NaBH4 in the presence of In(OH)3 as heterogeneous seeds and non-toxic polyvinylpyrrolidone (PVP) as surfactant. The incorporation of Fe3O4 nanoparticles served to bestow SPIDIN’s superparamagnetic properties which were confirmed in VSM analyses. Interestingly, the addition of Fe3+ led to the formation of In(OH)3 nanorods rather than the commonly observed nanocubes. In comparison to the In(OH)3 system having a band gap of 5.0 eV, two band gaps were observed for binary nanocomposite SPIDIN with one determined as 5.0 eV and the other as 2.8 eV via the use of Tauc’s plot method. SPIDIN was characterized using a combination of PXRD, FESEM, HRTEM, EDS, Zeta Potential, UV-vis diffuse reflectance spectroscopy and FTIR analyses. Under UVC illumination, SPIDIN dispersed on carbon allowed synergistic photodegradation of methylene blue up to 95% within 1 hr. In the presence of H2O2, free standing SPIDIN was able to disinfect Gram-positive Staphylococcus aureus and Gram-negative Salmonella enterica, signifying the potential of SPIDIN in biomedical waste treatment with H2O being the innocuous byproduct.

Photodegradation of Rhodamine B by CeO2-CuO Binary Composite Nanoparticles Synthesized by Self-Combustion Method

A novel binary composite CeO2-CuO has been synthesized via self-combustion method employing cerium and copper nitrates, and glycine as fuel, and was investigated as photocatalyst to test the photodegradation of Rhodamine B (RhB) dye with visible light. The nanocomposite has been characterized by thermogravimetric analysis (TGA) to establish the temperature of calcination, X-ray diffraction (XRD) structural and morphologic analysis, scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), which enables the chemical characterization/elemental analysis of materials, the photoluminescence (PL), UV-Vis Diffuse reflectance spectroscopy (UV-Vis DRS), measurement of specific surface (SBET ) by N2 adsorption and temperature programmed reduction (TPR) analysis. The XRD diffractogram shows that the composite is majorly composed of 65.2% CeO2 and 34.8 % CuO. The nanoscaled-tested samples have an average particle size of 40 to 65 nm. The energy gap of the material as synthesized was 2.05 eV. The TPR curves show 2 peaks of hydrogen consumption in the sample, corresponding to the decrease (reduction) of CuO particles caused by their interaction with CeO2.The results of the photocatalytic tests show 28% conversion in the photodegradation of RhB organic pollutant during 180 min under visible light. The CeO2- CuO material could be reused for treatment of wastewater during several cycles, which demonstrates its stability for the process.

Photocatalytic conversion of carbon dioxide to methanol over different precursors of graphitic carbon nitride supported on fibrous silica iron

In this study, the graphitic carbon nitride (g-C3N4) was successfully synthesized through thermal polymerization under three different g-C3N4 precursors such as urea (U-gC3N4), melamine (M-gC3N4) and dicyandiamide (D-gC3N4) and then doped into the fibrous silica iron (FSFe), denoted as U-gC3N4/FSFe, MgC3N4/FSFe, and D-gC3N4/FSFe, respectively. The synthesized catalysts were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), and UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis/DRS) and also tested for photocatalytic conversion of carbon dioxide (CO2) to methanol (CH3OH). The study indicated that altering the precursors had a substantial impact on the physicochemical features of the FSFe, which in turn increased the catalytic performance of the conversion of CO2 to CH3OH. U-gC3N4/FSFe exhibits the highest CH3OH yield (2.3 x 104 µmol gcat−1) compared to bare FSFe, D-gC3N4/FSFe and M-gC3N4/FSFe under visible light irradiation within 240 min. The higher CH3OH yield over U-gC3N4/FSFe is mostly owing to the lower bandgap energy of U-gC3N4/FSFe, as well as the advantageous interaction between g-C3N4 and FSFe.

N-doped Ti3C2-reinforced porous g-C3N4 for photocatalytic contaminants degradation and nitrogen reduction.

Herein, a series of N-doped Ti3C2/porous g-C3N4 composites are ultrasonically prepared from N-doped Ti3C2 and porous g-C3N4 under N2 atmosphere. The structure, morphology, and optical characteristics of the as-prepared composites are characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, etc. Moreover, photocatalytic measurements show that N-doped Ti3C2 is an excellent modifier for porous g-C3N4 to heighten its photocatalytic activity. Only 44.1% of rhodamine B can be degraded by the photocatalysis of pristine porous g-C3N4, while the photocatalytic degradation ratio of rhodamine B can reach up to 97.5% for the optimal N-doped Ti3C2 loading composites under visible light for 15 min. Moreover, the photocatalytic tests of N2 fixation confirm that the optimal composites show the highest production yield of NH4+ (11.8 μmol gcat-1 h-1), which is 2.11-folds more than that of porous g-C3N4 (5.6 μmol gcat-1 h-1). The reinforced photocatalytic properties are revealed to profit from the more photogenerated electrons and holes' separation, higher ability for light response, and more abundant active sites. This work develops the route for boosting the photocatalytic properties of porous g-C3N4 with N-doped Ti3C2.

G-C3N4 modified La0.01Sr0.99Ti0.99Cr0.01O3 for efficiently visible-light-driven photocatalytic water treatment

Water pollution caused by pharmaceutical wastewater has received increasing attention, and photocatalysis is a potential method to solve this problem. In this article, La and Cr co-doped SrTiO3 was prepared by electrospinning method, and was mixed with g-C3N4 to prepare La0.01Sr0.99Ti0.99Cr0.01O3/g-C3N4 (STO-1/CN) composite photocatalyst. The synthesized photocatalyst was characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and UV visible diffuse reflectance spectroscopy. The optimized STO-1/CN performs enhanced absorption of visible light, and separation and migration of carriers become more effective, which contributes to improve photocatalytic performance of STO-1/CN composites. The maximum photocatalytic activity, 0.0055 min−1 was obtained by heterojunction containing 50 wt% g-C3N4 (STO-50CN) in degrading CI under visible light, which was 4 and 2 times that of pure g-C3N4 and La0.01Sr0.99Ti0.99Cr0.01O3, respectively. The active species capture experiments indicate that the photocatalytic degradation of CI by composite photocatalysts is the result of the combined action of h+ and ·O2-. Based on the above conclusions, a possible mechanism of La0.01Sr0.99Ti0.99Cr0.01O3/g-C3N4 photocatalytic degradation of CI is proposed.