Facile Co-precipitation Route Research Articles

Fabrication of rare earth (Tb+3) and alkaline earth metal (Mg+2) Co-doped CdAl2O4@MXene composite: A unique approach to tune bandgap energy through quantum confinement effect for photocatalytic applications

The present work includes the use of effective strategy to improve the photocatalytic degradation activity of CdAl2O4 via dopant assimilation to enhance the bandgap energy (Eg) and to influence the light-sensitive activity of this spinel mixed oxide. In this study, CdAl2O4 (CA), Mg–CdAl2O4 (MCA), and Tb-doped Mg–CdAl2O4 (TMCA) were fabricated by the facile co-precipitation route and an ultra-sonication approach was used to prepare a composite of Tb-doped Mg–CdAl2O4 with MXene (TMCA@MXene). The obtained results from UV–Visible analysis deduce that there is an increase in Eg of MCA (2.51 eV) and TMCA (2.67 eV) as compared to pure CA (2.45 eV) which follows the quantum confinement effect accompanying the decrease in crystallite sizes of doped samples as compared to CA. The significant increase in bandgap energy of TMCA is due to the confinement of electrons in a small area and also due to the conversion of continuous energy levels into discrete energy levels. Moreover, UV–Visible spectroscopic analysis was made to evaluate the catalytic performance of fabricated photocatalysts against harmful organic pollutants. The photocatalytic study showed that the co-doped CdAl2O4 (TMCA) is a better photocatalyst than MCA and CA for the degradation of selected pollutants. Among all synthesized catalysts i.e. CA, MCA, TMCA, and TMCA@MXene, the highest photocatalytic activity was shown by MXene based nanocomposite. TMCA@MXene showed ∼86 % degradation of Rhodamine B (RhB) and 79.6 % degradation of Aspirin (acetylsalicylic acid). The outstanding photocatalytic efficacy of TMCA@MXene could be accredited to the quantum confinement effect produced by co-doping of alkaline earth metal (Mg+2) and rare earth metal (Tb+3) and large surface area, high conductivity, and excellent light harvesting capability provided by MXene sheets. Hence, TMCA@MXene could be an effective photocatalyst in future for the removal of toxic organic pollutants.

Fabrication of a novel polyvinylpyrrolidone/chitosan-Schiff base/Fe2O3 nanocomposite for efficient adsorption of Pb(II) and Hg(II) ions from aqueous solution

A novel magnetic polyvinylpyrrolidone/chitosan-Schiff base/Fe2O3 (PVP/CS-SB/Fe2O3) adsorbent was prepared by one-pot facile co-precipitation route for adsorption of Pb(II) and Hg(II) ions from aqueous solution. Fourier transform infrared-spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and Brunauer-Emmett-Teller (BET) were used to characterize the synthesized PVP/CS-SB/Fe2O3. The results predicted that the successfully synthesis of magnetic CSSB-PVP@Fe2O3. The effects of important factors such as pH solution, contact time, concentration of metal ions, adsorbent dose and co-existing ions on Pb(II) and Hg(II) adsorption were investigated. The maximum adsorption capacities of Pb(II) and Hg(II) ions at optimal conditions were 120 mg/g and 102.5 mg/g, respectively. The kinetic studies predicted that the adsorption followed the pseudo-second-order (PSO) model as chemisorption using the coordination of active sites of PVP/CS-SB/Fe2O3 with the metal ions and also n-π interactions. Reproducibility results predicted that the excellent regeneration ability after 6 adsorption cycles. According to the results of this work, the PVP/CS-SB/Fe2O3 nanocomposite is promising for Pb(II) and Hg(II) ions adsorption and can be potential as a simple, low-cost, high-efficient adsorbent for decontamination of other heavy metal ions from aqueous solution.

Antimony-doped cerium ferrite: a robust photocatalyst for the mitigation of diclofenac potassium, an emerging contaminant

The present work reports an improvement in the photocatalytic performance of cerium ferrite (CeFeO3) via doping of antimony (Sb) towards the photodegradation of toxic pharmaceutical pollutant i.e. diclofenac potassium. The variable concentrations of Ce1-xSbxFeO3 (x = 0.00, 0.01, 0.03, 0.05, 0.06, 0.07, 0.09) were prepared using facile co-precipitation route and subsequently characterized for their optical, structural, morphological, and dielectric properties using various analytical techniques. It was established that an increase in Sb concentration as dopant (up to x = 0.07) reduced the optical band gap from 2.74 eV to 2.42 eV making it suitable candidate for photodegradation. The X-ray diffraction (XRD) pattern revealed orthorhombic phase of synthesized materials with small crystallite sizes in the range of 15.28 to 2.42 nm. The high value of dielectric constant (3.5841 × 106) for Ce0.93Sb0.07FeO3 with small loss tan (3.1208) compared with the CeFeO3 indicated its ability as photocatalyst to effectively store charges to make them utilize for photocatalytic activity. The degradation efficiency of Ce0.93Sb0.07FeO3 reached 86.7% in 120 min of light irradiation under optimized conditions (pH = 4, catalyst dosage = 15 mg, primary drug concentration = 5 mg/L). Ce0.93Sb0.07FeO3 was also found to be stable over its multiple catalytic runs as only 6.5% decline in degradation efficiency was observed in recyclability test. The remarkable performance of antimony doped cerium ferrite against the removal of persistent pharmaceutical pollutant indicated its strong potential to be used in wastewater treatment in future works.

The high impact of zinc chromium oxide nanocombs on development of larvicidal and antimicrobial performance

Zinc chromium oxide (Cr/ZnO, 5wt.%) was prepared by a facile chemical co-precipitation route. The structure, composition, and chemical bonding were analyzed using X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR) indicating that chromium ions were integrated the host framework to form Cr/ZnO nanocomposite. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) micrographs showed comb-shaped nanoparticles with an average size 20 nm and large surface area. The energy gap of the thin films was estimated from T% and R% measurements which exhibit a strong optical absorption edge close to the visible spectrum. The insecticidal activity of the synthesized nanocombs against C. pipiens larvae was evaluated with LC50 (30.15 ppm) and LC90 (100.22 ppm). Besides, the nanocomposite showed high antibacterial performance against gram-positive bacteria (Bacillus subtilis) and gram-negative bacteria (Proteus vulgaris) with inhibition zones 21.9 and 19 mm, respectively.

Excellence evaluation of samarium doped Mn-Zn ferrite nanocrystals for room temperature HCl detection

The Samarium doped Smx: Mn0.8Zn0.2Fe2-xO4 (SMZFO) (x = 0.0–0.1) nanocrystals (NCs) have synthesized by a clean, environmentally friendly, simple, low temperature, facile chemical co-precipitation route. The surface features of the SMZFO NCs were exploited by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analyzer, vibrating sample magnetometer (VSM), and ultraviolet visible (UV) spectroscopy. The gas sensing measurements have been carried out by computer-interfaced gas sensing setup. The Sm 0.075: MZFO sensor exhibited maximum response of 47.24 % towards 100 ppm HCl at room temperature (RT, i.e., 27 °C). The minimal concentration detected by the sensor was 10 ppm with quickest response time (17.57 s) and recovery time (23.82 s). This is the first attempt made ever for detection of HCl by SMZFO NCs sensor at RT. To understand interaction mechanism of HCl gas molecules and SMZFO NCs sensor surface, impedance spectroscopy was employed. The SMZFO NCs sensor has demonstrated spectacularly improved gas sensing performance to open new doors in the era of gas sensor technology.

Synthesis of AgFeO2 delafossite catalyst and its application for photo-degradation of dye present in solution

The present work highlights the physicochemical properties of a series of novel silver ferric oxide (AgFeO2) delafossite nanoparticles while employing them as photocatalysts under visible light irradiation. The first sample was synthesized by a facile co-precipitation route (AFO-0) while the second and third samples were prepared at a constant hydrothermal temperature (180 °C) with varying reaction time of 2 h (AFO-2) and 8 h (AFO-8) and all three samples were subjected to visible light irradiation to photo-degrade Malachite Green (MG) dye. The crystalline structure, morphology, functional groups, elemental analysis, and optical property was conducted by their respective characterization techniques. The size of nanocrystals increased with the hydrothermal time and the average particle size of AFO-0, AFO-2 and AFO-8 were 87.7 nm, 154 nm, and 209.3 nm respectively, with AFO-8 exhibiting prominent hexagonal flake-like morphology. The direct band gap of AFO-0, AFO-2 and AFO-8 were 2.74 eV, 2.53 eV and 2.11 eV respectively and the Urbach energy was 0.20 eV, 0.217 eV and 0.254 eV respectively. The photo generated charge isolation efficiency of the samples was conducted where charge recombination sequence was of the order: AFO-8<AFO-2<AFO-0. The sample AFO-8 exhibited the optimum performance which resulted in excellent degradation of MG under visible light irradiation based on all the batch study experiments using solution pH, comparative analysis, catalyst dose, initial pollutant concentration as parameters. Finally, the optimum conditions at which AFO-8 degraded 97 % of MG were: 80 mg catalyst dose, pH 8, 20 mg L−1 (100 mL) MG, 90 min reaction time, 30 °C temperature and 130 rpm agitation speed. As per the quenching tests, the OH° and O2°− radicals were the governing reactive species that were responsible for degrading MG.

Effective catalytic and antimicrobial performance of multiple phase AgBr and polyacrylic acid doped nickel oxide nanostructures with In Silico molecular docking study

A facile co-precipitation route was adopted to synthesize NiO2 nanostructures (NSs) doped with various weight ratios (2 and 4 wt.%) of AgBr and a fixed amount of PAA. This study aimed to investigate the RhB degradation on multiple media with the antimicrobial activity of pristine and doped NiO2. The morphological, structural, elemental, and optical characterizations of prepared samples were examined. X-ray diffraction spectra (XRD) exhibited the hexagonal structure of NiO2 and confirmed the crystalline nature of the synthesized sample. The TEM images affirmed the nanoparticle and nanorod-like morphology. The UV–Vis analysis revealed that the absorption performance of synthesized samples is comprehensive in the ultraviolet region (277 nm) and band gap energy (Eg) decreased upon doping (4.1–3.36 eV). Fourier transform infrared (FTIR) has stretching and vibrational modes of Ni–O and other functional groups. NiO2 has a large band gap with a high charge recombination rate issue. The supreme performance of NiO2 can be credited to PAA and AgBr, which hinder the e−/h+ recombination process by charge separation. The catalytic activity of AgBr/PAA doped NiO2 demonstrates remarkable performance against RhB and benzoic acid, with maximum degradation in acidic medium and exhibited higher antimicrobial efficacy for Escherichia coli. Docking studies were employed to decipher the mechanism underlying the bactericidal activity of AgBr/PAA-doped NiO2 NSs and PAA-doped NiO2 NSs for β-lactamase and DNA gyrase inhibition.

A facile surfactant-assisted co-precipitation route preparation of LiNi0.5Mn1.5O4 cathode material

A facile surfactant-assisted co-precipitation route preparation of LiNi0.5Mn1.5O4 cathode material

Single-pot green synthesis of novel thiol-engineered iron thiomalate (Fe-TA) metal organic framework for selective adsorption of mercury in water

A novel thiol-functionalized iron thiomalate metal organic framework (Fe-TA) was synthesized using a facile, single step and green coprecipitation route. The synthesis procedure was optimized and it was proven to be an exclusive way over conventional hydrothermal method. This newly reported MOF was characterized in detail using XRD, FTIR, FESEM, EDX, BET, and Zetasizer to determine the morphological and compositional properties that indicated to the amorphous nature of Fe-TA. The MOF demonstrated high adsorption of aqueous inorganic mercury that was thoroughly explored in varying range of experimental conditions, namely, adsorbent dose, solution pH, feed Hg concentration, temperature, and time to analyze the adsorption isotherms along with the kinetic and thermodynamic parameters. The maximum capacity was evaluated as 1223 mg/g at 298 K using the Langmuir isotherm model and the adsorption followed pseudo-second order kinetics. XPS analysis was used to confirm chemisorption as the governing mechanism by strong lone pair interactions between S and Hg forming a Hg-S complex. The high negative zeta potential of Fe-TA (-18 mV) aided in strong electrostatic interactions with Hg2+ favoring the adsorption process. The selective affinity (Kd: 5.35 × 105 mL/g) and substantial regenerative quality (>93%) of the adsorbent was also reported.

Effect of iron concentration on the structure and thermoelectric performance of copper sulphide nanostructures

Nanostructured copper sulfide (CuS) and iron (Fe) doped CuS materials were synthesized through facile chemical co-precipitation route by using ammonia as a capping agent. Evaluations of the structural, morphological, and electrical behavior of the fabricated materials were carried out by employing XRD, SEM, EDS, FTIR, and two probe I–V method. XRD exhibited cubic phase of CuS and later on peak broadening was observed in the samples upon Fe incorporation. Cu–S linkage and presence of other functional groups were figured out through application of FTIR. Furthermore, a boost in electric current has observed across the synthesized samples during the study of I–V characteristics and such behavior can be attributed towards increase of Fe content, temperature, and voltage across the synthesized nanomaterials.

Novel red-emitting orthorhombic GdInO3:Eu3+ perovskite phosphor: Structural resolution, Judd-Ofelt theory, and comparative investigation with hexagonal counterpart

A novel orthorhombic GdInO3:Eu perovskite red phosphor, endowed with good luminescence properties, was synthesized via a facile co-precipitation route plus controllable thermolysis. Its structural features, optical properties, and luminescent behaviors were compared with the hexagonal counterpart in detail. The two GdInO3 matrixes have relatively wide direct bandgaps (∼5.07 eV for orthorhombic perovskite and ∼5.13 eV for hexagonal phase) and low phonon energies (∼368 cm−1 for orthorhombic perovskite and ∼425 cm−1 for hexagonal contrast). Eu3+ substitution for Gd3+ occupies the C2v symmetry site without an inversion center in orthorhombic GdInO3, while the hexagonal GdInO3 provides two crystallographic positions for Eu3+ residence (∼2/3 at C3 site and ∼1/3 at C6v site). The emission spectra of two phosphors present characteristic 5D0→7FJ transitions of Eu3+ and the optimum activator concentrations are both 10 at.%. They also have good thermal stability of luminescence with relatively high similar activation energies of ∼0.25 eV. F+ center (VO∙ oxygen vacancy) is the primary defect form in the two perovskites, which has little effect on the entire red emission of orthorhombic phosphor but shifts the chromaticity coordinate of hexagonal contrast toward orange region. The orthorhombic GdInO3:Eu phosphor exhibits stronger emission intensity, a longer fluorescence lifetime, and a higher color purity than the hexagonal counterpart. Judd–Ofelt theory further confirms that orthorhombic GdInO3:Eu is an efficient red-emitting material with the relatively large parameters of Ω2 = 7.01 × 10–20 cm–2 and Ω4 = 2.85 × 10–20 cm–2.

A facile synthesis route and photo-catalytic properties of mixed-phase bismuth molybdate

The polymorphs (α – Bi2Mo3O12, β – Bi2Mo2O9, γ – Bi2MoO6) of bismuth molybdate (BMO) exhibit photo-catalytic activity. Among them, the β phase exhibits good photo electrochemical (PEC) performance but suffers from stability issues. In this work, mixed-phase BMO compounds were synthesized using a facile co-precipitation route. The processed BMO showed a band gap of 2.46 eV. The sample with predominantly γ-BMO (γ – Bi2MoO6) with lower α and β content exhibited better photo-electrochemical performance with a photocurrent density of 1.12 μA/cm2 and lower charge transfer resistance compared to the BMO-1 sample with a larger amount of α and β phases. Both the samples displayed n-type conductivity and excellent photoresponse under chopped illumination.

Green synthesis of nickel oxide coupled copper hexacyanoferrate (NiO2–CuHCF) nanocomposites for efficient and highly stable natural sunlight-driven photocatalytic degradation of wastewater pollutants

Metal hexacyanoferrates are found to be the promising candidates utilized to degrade toxic dyes from waste water under natural sunlight irradiation. Coupling of metal hexacyanoferrate with metal oxide enhances the degradation efficacy. In present work, nickel oxide coupled copper hexacyanoferrate nanocomposites (NiO2–CuHCF) are synthesized by employing facile co-precipitation route. XRD reveals the incorporation of NiO2 with CuHCF. SEM confirms the sheet like structures of NiO2–CuHCF nanocomposite. TEM demonstrates the even distribution of elements present in the NiO2–CuHCF nanocomposite. XPS shows the active participation of constituents having different valence states. The UV–Vis (DRS) is employed to measure the optical properties. The band gap of nickel oxide coupled copper hexacyanoferrate nanocomposite (NiO2–CuHCF) decreases in comparison with pure copper hexacyanoferrate (CuHCF) from 1.23 to 1.14 eV. 97% degradation of Methyl blue (MB) is observed in just 110 min by NiO2–CuHCF nanocomposite when exposed to natural sunlight. Moreover, it also retains 92% photocatalytic efficiency over 6 cycles which shows its excellent stability and reusability. The improved photocatalytic performance of NiO2–CuHCF nanocomposite is attributed to their sheet resembling morphologies which may provide adequate active sites responsible to transport more charge carriers and also reduce charge recombination. In general, this research may open new avenue to use CuHCF with the addition of NiO2 in future as an efficient degradation agent at industrial level.

Sol-gel auto-combustion synthesis of a novel chitosan/Ho2Ti2O7 nanocomposite and its characterization for photocatalytic degradation of organic pollutant in wastewater under visible illumination

In the last few years, the release of toxic contaminants into the ecosystem has expanded dramatically. Hence, multiple photocatalysts have been improved for the elimination of toxic contamination. The manufacture of photocatalysts based on nanostructures is a promising strategy to improve photocatalytic potential. In this regard, Ho2Ti2O7 and chitosan-coated Ho2Ti2O7 nanocomposites have been manufactured through a facile auto-combustion and co-precipitation route. Diverse factors, including calcination temperature, type of precursor of titanium, solvent, and types of fuels, can affect the structure, purity, morphology, and particle size of samples. Ho2Ti2O7 nanostructures are a good candidate for photocatalytic evolution owing to their adequate bandgap (2.5 eV) in the visible region. This is the first study of the photocatalytic efficacy of Ho2Ti2O7 and chitosan-coated Ho2Ti2O7 nanocomposites. Their photocatalytic performance was explored over several dyes as pollutants, including malachite green, methyl violet, eriochrome black T, methylene blue, acid red 198, methyl orange, and thymol blue under visible radiation. Besides, diverse parameters, such as Ho2Ti2O7 contents, dye levels, were studied on the efficiency of the reaction. The results demonstrated that the maximum efficiency of Ho2Ti2O7 and its chitosan-coated was perceived over malachite green with degradation percentages of 95.7 and 79.9%, respectively. Ho2Ti2O7 nanostructures were highly stable due to their recyclability test and kept their photocatalytic potential over five cycles. The decrease in photocatalytic efficiency in the 5th period is 7.1%.

Structural, morphological and optical aspects of novel synthesized pristine and hafnium doped nickel oxide nanoparticles

The manuscript attempted to synthesise novel pure and Hafnium doped Nickeloxide (HNO) nanospheres using the facile co-precipitation route. Though the material is novel, a thorough enquiry on the structural, morphological and optical aspects of HNO is indeed and is carried out via various characterization techniques. The synthesis route guaranteed the production of nanosized spheres with reduced crystallite size was confirmed with structural and morphological studies. X-ray diffraction XRD) confirms the face centred cubic structure of NiO nanostructures, and it upholds the evidence of doping in NiO lattice. The morphological analysis was carried out with the scanning electron microscope (SEM) and transmission electron microscope, confirming the spherical NiO nanostructures and the effect of doping on its morphological properties. Furthermore, the UV analysis assessed the absorption spectra and the bandgap value is calculated using Kubelka–Munk plot. Moreover, PL analysis revealed that the doped samples exhibit a high bandgap above 3 eV and have strong emissions under 266 nm and 280 nm excitation wavelength.

Synthesis of hierarchical transition metal oxyhydroxides in aqueous solution at ambient temperature and their application as OER electrocatalysts

First-row (3d) transition metal oxyhydroxides have attracted increasing attention due to their various advantages. Although investigating the oxidation mechanism and processing such materials into hierarchical architectures are greatly desired for their further development, it remains unclear how the oxidation state change occurs, and efforts to produce hierarchical oxyhydroxides in compliance with high ecological and economic standards have progressed slowly. Here, we describe a facile one-step coprecipitation route for the preparation of hierarchical CoOOH, NiOOH and MnOOH, which involves the diffusion of NH3 originating from ammonium hydroxide solution into an aqueous solution containing metal ion salts and K2S2O8. Comprehensive characterizations by scanning electron microscope, transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and in situ pH measurement demonstrated that K2S2O8 induces the oxidation state change of metal ion species after the start of hydrolysis. Meanwhile, it was found that, benefiting from the OH– concentration gradient created by the NH3 diffusion method and the suitable growth environment provided by the presence of K2S2O8 (high nucleation rate and secondary nucleation), the formation of hierarchical oxyhydroxide structures can be realized in aqueous solution at ambient temperature without the use of heat energy and additional structure-directing agents. The hierarchical CoOOH structures are performed as the electrocatalysts for the oxygen evolution reaction in alkaline media, which exhibit good activity with an overpotential of 320 mV at 10 mA cm−2 and a low Tafel slope of 59.6 mV dec–1, outperforming many congeneric electrocatalysts. Overall, our study not only provides important insights to understand the formation mechanism of hierarchical oxyhydroxides, but also opens up new opportunities for the preparation of hierarchical oxyhydroxides via a facile, green and low-cost method.

Study of structural and optical properties of europium ion activated bismuth oxide nanophosphors

The current study examines the structural and optical features of un-doped and a series of Eu3+ ion-doped bismuth oxide nanophosphors synthesized via a facile, low-cost, and room temperature co-precipitation route. X-ray diffraction (XRD) analysis confirms the monoclinic crystal structure without any trace of impurity. The FTIR spectroscopic analysis of the samples has been taken in 400–4000 cm−1 wavenumber range to analyze the bonding states and functional groups of the species. Optical properties of the samples have been investigated using UV–Vis and photoluminescence (PL) spectroscopy. We observed a slight increase in the band gap in the doped samples (2.79–2.81 eV) as compared to the bismuth oxide host (2.77 eV). The photoluminescence emission studies have been carried out under 466 nm excitation wavelength over the range of 550–750 nm. The most prominent peak in the emission spectra is observed at 612 nm corresponding to(5D0 → 7F2)transition of Eu3+ ion. An explicit augmentation in the emission intensity is observed in 7 mol% Eu3+ doped Bi2O3 nanophosphor. The emission spectra were used to calculate the CIE chromaticity coordinates and CCT of the phosphors. The CIE coordinates depict an evident red-shift in the Eu3+ doped phosphors. The CCT values have been sufficiently alleviated after Eu3+ doping. Thus, our study corroborates an evident red-shift in the aforementioned optimized composition and suggests that it is a potential candidate for lighting and display devices.

Fabrication of dual Z-scheme TiO2-WO3-CeO2 heterostructured nanocomposite with enhanced photocatalysis, antibacterial, and electrochemical performance

Direct dual Z-scheme heterostructured nanocomposite TiO2-WO3-CeO2 (NC) and pristine metal oxides nanostructures (NSs) were fabricated using a facile co-precipitation route. XRD, FTIR, and Raman data have confirmed the formation of NSs and NC. FESEM images showed quasi-mesoporous morphology of as-grown nanocomposite. EDX analysis confirmed the existence of titanium (Ti), cerium (Ce), and tungsten (W) in grown NC. The energy bandgap of NC was narrow 2.45 eV as compared to NSs. The higher electrical conductivity and lower recombination rate of NC were observed in IV and PL analysis. The photodegradation efficiency of NC was recorded 99.8% after 60 min under sunlight radiation against methylene blue (MB), which was significantly higher than NSs. NC catalyst has shown excellent photodegradation against other organic pollutants and has superior recyclability up to 7th cycle toward MB dye with a ~ 6% deficit in photodegradation efficiency. The antimicrobial activity results indicated the higher inhibition ability of NC against E. coli, K. pneumoniae, S. aureus, P. Vulgaris, and P. aeruginosa with maximum inhibition zone diameter 25, 29, 26, 28, and 27 mm, respectively. The electrochemical tests including CV, EIS, and GCD exhibited the superior capacitive behaviour of NC. These results demonstrate that grown NC is an efficient material for electrochemical devices, water purification, and biomedical applications.

Trace holmium assisting delaminated OMS-2 catalysts for total toluene oxidation at low temperature

In this study, octahedral molecular sieve (OMS-2) is successfully delaminated by using trace holmium (Ho) via a facile redox co-precipitation route, which exhibits high performance for the total toluene oxidation at low temperature. High resolution transmission electron microscope (HRTEM), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) analyses verify that abundant multi-phase interfaces and lattice dislocations are formed on the obtained delaminated OMS-2 by the Ho (Ho-OMS-2), which can induce more active oxygen species. In particular, the delaminated OMS-2 with a trace Ho amount has a high Oads/Olatt ratio with a balanced ratio of Mn3+ and Mn4+, demonstrating much higher activity (T100% of 228 °C even under 5 vol% H2O vapor over 0.5% Ho-OMS-2) than the parent OMS-2 (T100% of 261 °C) for the total toluene oxidation. Furthermore, the positive effect of the introduction of H2O on catalytic activity, especially the enhancement of the conversion of intermediates into CO2 and H2O, is verified by the in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS). Based on these results, the reaction mechanism for toluene oxidation over the OMS-2 based catalyst is proposed. It is expected to provide an effective preparation method to obtain high-performance catalysts for the VOCs oxidation at low temperatures.

Structural and thermal properties of pure and chromium doped zinc oxide nanoparticles

Pure ZnO and Cr-doped ZnO nanoparticles have been synthesized via a facile chemical co-precipitation route and their structural, thermal characteristics were discussed systematically. In the experimental producer, the doping concentration has varied the range, 0.05–0.1 M, while calcined at 600 °C. The influence of Cr-doping on the physical characteristics of ZnO nanoparticles was investigated and addressed. As-prepared samples were analyzed via XRD, FTIR, TGA/DTA, BET, and ICP-MS. XRD analysis shows that ZnO and Cr doped ZnO nanoparticles with average particle sizes between 23 and 39 nm were successfully developed with hexagonal wurtzite structure. The FTIR spectroscopy analysis confirms the existence of chromium in the doped ZnO nanoparticles and the formation of ZnO. The TGA/DTA analysis shows that Cr–ZnO nanoparticles are more thermally stable than ZnO nanoparticles. Moreover, the dopant concentration has been analyzed via ICP-MS and showed a good agreement with the expected chromium concentration. The BET surface area measurement shows that 176.25 m2/g and 287.17 m2/g for un-doped ZnO, and 0.1 M Cr-doped ZnO nanoparticles, respectively. Hence, doping of Cr enhances the surface area and thermal stability. Thus, Cr–ZnO nanoparticles show good thermal stability, and high surface area, which is an excellent characteristices of nanomaterials.Graphic abstract