HRTEM Images Research Articles

Studying the properties of green synthesized silver oxide nanoparticles in the application of organic dye degradation under visible light.

In present study the green synthesis of silver oxide nanoparticles has been effectively achieved using novel plant extract Phragmanthera Macrosolen. This method provides sustainable alternative for nanoparticle synthesis, demonstrating the potential of Phragmanthera Macrosolen as a reducing and stabilizing agent in the production of Ag2O NPs. The synthesized nanoparticles were characterized for their structural, morphological, and optical properties, confirming their successful formation and potential applications in various fields. The effects of different pH values and annealing temperature of the samples on the properties of Ag2O NPs formations, as well as photo-catalytic activities towards Toluidine Blue dye degradations, were studied. Powder XRD reveals that the crystallite natures of Ag2O NPs a long with crystalline size ranges from 25.85 to 35.90nm. FIB-SEM and HR-TEM images displayed that the Ag2O NPs as spherical shapes. UV-vis spectroscopy displayed that Ag2O NPs belong to a direct-band gap of 2.1-2.6eV. FTIR- study shown that the green synthesized Ag2O NPs may be steadied via the interfaces of -OH as well as C = O groups in the carbohydrate, flavonoid, tannin, as well as phenolic acid existing in P. macrosolen L. leaf. The chemical states, electron-hole recombinations and purity of Ag and O in the synthesized Ag2O NPs were confirmed through X-ray Photoelectron Spectroscopy (XPS) and PL analysis respectively. Fascinatingly, the synthesized Ag2O NPs at pH 12 displayed high photo-catalytic degradations for TB dyes. The photo-catalytic degradations of the TB dyes were monitored spectro-photo-metrically in wave-length ranges of 200-900nm, as well as high efficiency (98.50%) with half-life of 9.5798min and kinetic rate constant of 0.07234min-1, was obtained after 45min of reactions. From this study, it can be concluded that Ag2O NPs synthesized from Phragmanthera Macrosolen aqueous extract are promising in the remediation of environmental pollution and water treatment. In this light, the study reports that Phragmanthera Macrosolen green synthesis of Ag2O NPs can effectively address environmental pollution in cost-effective, eco-friendly, and sustainable ways.

Green biogenic synthesis of magnetite nanoparticles from indigenous Banksia Ashbyi leaf for enhanced sonochemical dye degradation

Abstract Developing alternative green and sustainable technologies to prevent, reduce, and remove toxic dyes present in effluent generated by the textile industry is of global importance. In this study, magnetite (Fe3O4) nanoparticles (MNPs) were successfully synthesized using a co-precipitation method that used Indigenous Banksia Ashbyi (BA) leaf extract in varying amounts (BA-MNP 1 to BA-MNP 4), to modulate particle size and size distribution. The formation of the MNPs was confirmed by a range of characterization techniques that included UV–visible spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD) spectroscopy, thermo-gravimetric analysis (TGA) and scanning (FIBSEM) and high-resolution transmission (HRTEM) electron microscopy. The presence of the Fe–O bond located at 551 cm−1 in the FTIR spectra and XRD analysis of the samples confirmed the formation of crystalline MNPs. FIBSEM and HRTEM images of the BA-MNP 4 sample confirmed the MNPs were spherical (18 ± 5 nm) and tended to agglomerate. Moreover, UV–visible spectrophotometry revealed a board absorption band and an optical band-gap energy of 2.65 eV. The catalytic activity of BA-MNP 4 samples towards the degradation of a commercially available navy-blue RIT dye (BRD) were investigated under three operational senarios: 1) ultrasonic irradiation (US) + BRD; 2) BA-MNP 4 + BRD, and 3) US + BRD + BA-MNP 4. The investigation found there was an additive effect when US (80 W) was used in conjunction with BA-MNP 4 s during the dye degradation process. With no US, the BA-MNP 4 sample only achieved a dye degradation of 52% in 25 min. However, over the same period of time with US, the BA-MNP 4 sample achieved a dye degradation of 89.92%. In addition, kinetic modelling found the combined US and BA-MNP 4 process followed a pseudo-first-order kinetic model.

Controlled Synthesis of Iron Oxide Nanoparticles via QBD for Biomedical Applications

Introduction: Iron oxide nanoparticles have gained significant attention in pharmaceutical applications because of their unique properties. The hydrothermal method is employed for the synthesis of iron nanoparticles [IONPs], which offers advantages such as uniform composition and size distribution. Method: However, the size and properties of IONPs can be influenced by various factors. In this study, we utilized quality by design [QBD] via response surface methodology to investigate the impact of temperature, time, and pH on the size of hydrothermally prepared IONPs. The optimized synthesis conditions were determined, and the resulting nanoparticles were characterized using techniques such as dynamic light scattering [DLS], scanning electron microscopy [SEM], transmission electron microscopy [TEM], vibrating sample magnetometry [VSM], X-ray diffraction [XRD], and Fourier-transform infrared spectroscopy [FTIR]. Results: The findings contribute to a better understanding of the controlled synthesis of IONPs and their potential applications in nanomedicine. The XRD characterization revealed that the product was Fe3O4. The FTIR results indicate that Fe3O4 nanoparticles were coated with PEG- 400. The SEM and HRTEM images of the Fe3O4 nanoparticles showed that they were spherical and had a well-distributed size with an optimized hydrodynamic size of 65 nm. Conclusion: The magnetic properties of the Fe3O4 nanoparticles indicated that they exhibited ferromagnetic properties. These prepared nanoparticles are suitable for biomedical purposes, like serving as contrast agents for magnetic resonance imaging in different cancers and delivering drugs.

Improving thermoelectric performance of Nickel substituted ZnSb alloy through carrier engineering and nanostructuring

Zn1-xNixSb (0 ≤ x ≤ 0.08) nanostructures were prepared by the planetary Ball milling technique. XRD analysis confirms the phase purity and orthorhombic crystal structure of the samples. FESEM analysis shows the spherical morphology of the Zn1-xNixSb samples. The EDX and elemental mapping analysis confirms the composition and elemental distribution of Zn1-xNixSb (0 ≤ x ≤ 0.08) alloys. HRTEM images clearly show the interfaced grains with grain boundaries. DRS-UV analysis revealed the narrowing of bandgap while increasing the Ni content in Zn site due to alloying effect. The synthesized Zn1-xNixSb alloys show low resistivity compared to pure samples due to high carrier concentrations. Seebeck coefficient of Zn1-xNixSb alloys were measured from room temperature to 635 K. A high-power factor of 1344 µW/m K2 was obtained for the Zn0.98Ni0.02Sb sample at 533 K compared to pristine ZnSb (574 µW/m K2 at 533 K). High thermoelectric figure of merit (zT) of 0.69 was achieved for Zn0.98Ni0.02Sb sample at 533 K compared to pristine ZnSb (zT of 0.34 at 533 K). The experimental results illustrated that Nickel substitution is a one of the possible ways to improve the thermoelectric figure of merit of ZnSb alloys.

Poly(aniline)-multiwall carbon nanotube (PANI@MWCNT) composite as high-cost Pt free counter electrode for dye-sensitized solar cells

In this study, we synthesized a poly (aniline)-multiwall carbon nanotube (PANI@MWCNT) composite for use as a counter electrode (CE) in dye-sensitized solar cells. Moreover, FE-SEM and HR-TEM images of PANI@MWCNT revealed carbon nanotube/ropes embedded in the polymer matrix. An X-ray diffraction pattern confirmed the amorphous nature of the composite. Further, Electrochemical impedance spectroscopy studies indicated a charge transport resistance value (Rct) of 4.36 KΩ for PANI@MWCNT. CV studies demonstrated improved electrocatalytic performance and faster redox behavior in the PANI@MWCNT composite. BET analysis measured the pore size of the as-prepared composite to be 15–50 nm. Subsequently, the as-synthesized PANI, PANT@MWNCT, pristine MWCNT, and platinum were evaluated as CEs in DSSCs using a polyethylene oxide polymer-based liquid electrolyte and a TiO2 nanocrystalline photoanode. Among these CEs, the PANI@MWCNT CE exhibited an efficiency of 8.07 %, and the stability test indicated that the as-prepared composite CE retained 7.81 % efficiency after 15 days.

Synergistic plasma and platinum catalysts interactions in CO2 reforming of propane at room temperature: The role of supports

This study investigates the synergistic impact of plasma and catalyst in a hybrid non-thermal plasma system integrated with 1 wt% Pt catalysts supported on diverse catalyst supports (γ-Al2O3, SBA-15, HZSM-5, CeO2, TiO2, and multi-wall carbon nanotube (CNT)) at ambient conditions in dry reforming of propane (DRP). To optimize the reaction, the impact of in-situ plasma reduction time was investigated over the Pt/Al2O3 catalyst at varying durations before the DRP reaction. The most favorable catalytic performance was observed at a reduction time of 60 min due to having the highest surface area (284 m2/g), which might result in smaller Pt particle size, and the effective reduction of oxidation states to Pt0. A comparison of reduction sources also revealed that the plasma-reduced catalyst outperformed the other, which was attributed to the agglomeration of Pt active sites during the thermal reduction process. The chemo-physical properties of different catalysts directly affected the plasma characteristics and catalytic performance. Pt/Al2O3 exhibited the highest performance, attributed to having the smallest mean Pt particle size (0.94 nm) and highest discharge power (13.97 W), effective capacitance (1.41 nF), and charge transfer (0.34 μC) during DRP reaction, leading to a 13 % and 15 % increase in CO2 and C3H8 conversions, respectively, compared to plasma-only mode. The catalytic performance showed that the synergy of catalysts with higher basic sites and plasma characteristics, along with smaller Pt particle size, resulted in high reactant conversion and syngas selectivity. Binary HRTEM images also indicated the presence of more soft carbon (coke) in the pore channels of the spent Pt/HZSM-5 catalyst than in spent Pt/Al2O3.

Photocatalytic Nanocomposite Based on Titanate Nanotubes Decorated with Plasmonic Nanoparticles for Enhanced Broad-Spectrum Antibacterial Activity.

Infections resulting from microorganisms pose an ongoing global public health challenge, necessitating the constant development of novel antimicrobial approaches. Utilizing photocatalytic materials to generate reactive oxygen species (ROS) presents an appealing strategy for combating microbial threats. In alignment with this perspective, sodium titanate nanotubes were prepared by scalable hydrothermal method using TiO2 and NaOH. Ag, Au, and Ag/Au-modified titanate nanotubes (TNTs) were prepared by a cost-effective and simple ion-exchange method. All samples were characterized by XRD, FT-IR, HRTEM, and DLS techniques. HRTEM images indicated that the tubular structure was preserved in all TNTs even after the replacement of Na+ with Ag+ and/or Au3+ ions. The antibacterial activity in dark and sunlight conditions was evaluated using different bacterial strains, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The results showed that while a low bacterial count (∼log 5 cells per well) was used for inoculation, the TNTs exhibited no antibacterial activity against the three bacterial strains, regardless of whether they were tested under light or dark conditions. However, the plasmonic nanoparticle-decorated TNTs showed remarkable activity in the dark. Additionally, Ag/Au-TNTs demonstrated significantly higher activity in the dark compared with either Ag-TNTs or Au-TNTs alone. Notably, under dark conditions, the Au/Ag-TNTs achieved log reductions of up to 4.5 for P. aeruginosa, 5 for S. aureus, and 3.7 for E. coli. However, when exposed to sunlight, Au/Ag-TNTs resulted in a complete reduction (log reduction ∼9) for P. aeruginosa and E. coli. The combination of two plasmonic nanoparticles (Ag/Au) decorated on the surface of TNTs showed synergetic bactericidal activity under both dark and light conditions. Ag/Au-TNTs could be explored to design surfaces that are responsive to visible light and exhibit antimicrobial properties.

Carbothermally synthesized, lignin biochar-based, embedded and surface deposited nano zero-valent iron composites: Comparative material characterization, selective gas adsorption and nitroaromatics remediation

Biochar (BC) with nanoscale zero valent iron (nZVI) incorporation offers advantageous materials for water purification. Even though the most common approach for nZVI incorporation is the deposition on the carrier surface, embedding in the support matrix has also been reported. However, the behavior of the embedded material in contaminant removal has not been adequately studied while characteristics and the remediation capabilities of the two materials have not been compared. Present study focuses on preparing and extensively characterizing two materials: nZVI embedded in (Lig-e-nZVI) and surface deposited on (Lig-s-nZVI) lignin BC with subsequent comparative study of remedial action for two nitroaromatics, p-nitroaniline (pNA) and p-nitrophenol (pNP). The synthesis of Lig-e-nZVI and Lig-s-nZVI involved simultaneous and subsequent pyrolysis of lignin and carbothermal reduction of the iron salt, respectively. Lig-e-nZVI showed enhanced porosity. XRD confirmed the formation of Fe0. HR-TEM images proved the core-shell structure of nZVI, and an interlayer spacing of 0.36nm of the shell verified that the Fe0 particles are encapsulated with graphene while an iron carbide inner layer was also observed, thinner in Lig-e-nZVI and thicker in Lig-s-nZVI. Band gap energy of 2.54eV suggested a photocatalytic activity of both materials. Best fitted Sips isotherms showed 23.1 and 13.1mgg-1 capacities for Lig-s-nZVI in pNP and pNA adsorption respectively. Highest stability was portrayed by Lig-e-nZVI over 4 regeneration cycles. The physicochemical features of the developed materials further enable selective gas adsorption. Findings provide new insights into physicochemical characteristics and remedial actions of differently synthesized nZVI-BC composites.

Slope-structure design towards high-stability P2-Na0.67MnO2 cathode

Layered Mn-based oxide P2-Na0.67MnO2 (NMO) arouses enormous interest for its high specific capacity, easy preparation and low cost. Meanwhile, the P2 → O2 phase transition derived from the slippage of transition metal (TM) layer leads to the inferior performance. Herein, we design a co-doping into Na+ (102 pm) lattice site with smaller-sized Li+ (76 pm) and larger-sized K+ (138 pm) to construct a slope-structured P2-Na0.63K0.02Li0.02MnO2 (NKLMO). The anchored Li+ and K+ can serve as pillar effects and form a geometrically stable resembling triangular structure in the Na-interlayer. Moreover, such a slope-structure is clearly verified by the HRTEM images. In-situ XRD and in-situ EIS tests efficaciously clarify the improved structural stability and even lower impedance during cycling within 2.0–4.2 V, respectively. DFT calculations further confirm the stronger metallicity of NKLMO electrode than the bare NMO originated from the more mobile free electrons surrounding the vicinity of Fermi level. By grace of the more stable slope-structure and faster reaction kinetics, NKLMO is capable of displaying high initial capacity (206.5 mA h/g) and energy density (540 W h kg−1), with a competitive cycling stability at both low and high current rates (96 %@100 cycles@0.1C; 88.4 %@500 cycles@5C). This slope-design is above rubies for tuning chemistry environment to exploit high-stability P2-phase cathodes for sodium-ion batteries.

Sustainable synthesis of multifaceted copper oxide nanoparticles from Euphorbia tirucalli: Unveiling antimicrobial and catalytic potential

This work presents Euphorbia tirucalli mediated green synthesis of multi-purpose copper oxide nanoparticles (ET@CuO-NPs) exhibiting enhanced antimicrobial activity. These plant extract capped nanoparticles were characterized using sophisticated techniques such as FTIR, Raman, UV–Vis, SEM, HR-TEM, DLS, zeta potential, XPS and XRD. A uniform rod-shaped morphology was observed in HR-TEM images with size around 50 nm. Antibacterial and antifungal activity was investigated by agar well diffusion method. The bactericidal action was confirmed by zone of inhibition of 28 mm and 34 mm respectively against gram-negative and a gram-positive bacterium. The nanoparticles also show excellent antioxidant activity via free radical scavenging by DPPH. The scope of ET@CuO-NPs was extended to catalytic reduction of nitroaromatic compounds into their corresponding amino derivatives. The reduction of 4-nitrophenol, a model nitroaromatic pollutant could be completed within just 6 min with a recycling efficiency of 8 cycles. Thus, the multifaceted ET@CuO-NPs exhibited diverse therapeutic and catalytic potential.

SnO2QDs: Photophysical properties, photocatalytic activity, mineralization financial cost and recycling process during industrial effluent treatment

This study investigates the synthesis, characterization, and photocatalytic performance of pure and titanium-doped tin dioxide quantum dots (SnO2QDs) prepared via a sonochemical method. The structural and morphological properties were thoroughly examined using XRD, FTIR, SEM-EDX, HRTEM, UV-DRS, and BET surface area analysis. XRD confirmed the formation of tetragonal SnO2 with high phase purity and average crystallite sizes of 2.95 nm for SnO2QD1 (calcined at 270 °C) and 8.36 nm for SnO2QD2 (calcined at 480 °C). Titanium doping was achieved without altering the SnO2 crystalline structure, as evidenced by FTIR spectra showing characteristic vibrational modes and hydroxyl groups. HRTEM images revealed spherical nanoparticles with diameters of 3.2 nm for SnO2QD1 and 9.7 nm for SnO2QD2, supported by SAED patterns confirming their polycrystalline nature. The photocatalytic efficiency was evaluated through the degradation of Reactive Yellow 145 dye under Xenon lamp irradiation. SnO2QD1 exhibited superior photocatalytic activity with a rate constant (k) of 6.94 × 10−3 s−1, achieving 80 % dye degradation in 105 min, compared to SnO2QD2 with a k of 4.50 × 10−3 s−1 and 83 % degradation in 120 min. Titanium doping further enhanced the photocatalytic performance, with SnO2QDT1 (1 % Ti) showing a k of 9.89 × 10−3 s−1 and 80 % degradation in just 90 min, three times more efficient than SnO2QDT2 (9 % Ti). BET analysis indicated a significant reduction in surface area with increased calcination temperature, from 154 m2/g for SnO2QD1 to 86 m2/g for SnO2QD2. The bandgap energies, determined via UV-DRS, were 3.30 eV for SnO2QD1 and 3.34 eV for SnO2QD2, slightly reduced in Ti-doped samples, enhancing visible light absorption. The SnO2QDs demonstrated excellent recyclability, maintaining photocatalytic activity over eight reuse cycles. Economic analysis based on Saudi Arabian electricity tariffs highlighted the cost-effectiveness of SnO2QD1, offering a 5.2 % reduction in energy consumption compared to SnO2QD2. These findings position SnO2QDs as highly efficient and sustainable photocatalysts for industrial wastewater treatment applications.

Enhanced hypersensitive (5D0→7F2) transition characteristics of Eu3+ doped β-Ga2O3 microrods

Exploring and realizing the luminescence characteristics of rare earth metal (RE) ions doped gallium oxide (Ga2O3) is crucial for developing optoelectronic device applications. The current research used the solid-state reaction approach to synthesize Ga2O3 microrods doped with various europium (Eu3+) concentrations (0.1, 0.2, 0.3, 0.5, 0.75, and 1 mol). X-ray diffraction (XRD) and Raman spectral analyses confirm the monoclinic structure of β-Ga2O3. The intensity of the Raman phonon modes decreased and a peak shift was observed for Eu:β-Ga2O3. The electron microscopy (SEM, TEM) images depicted a nearly uniform distribution of microrods for undoped and Eu:β-Ga2O3 samples. The interplanar distance (d = 0.290 nm, 0.561 nm, and 0.433 nm), from HR-TEM images, corresponding to (0 0 4), (1 0 0), and (1 0 2) crystallographic orientations confirm the monoclinic structure of β-Ga2O3. The elemental mapping images showed a nearly homogeneous Ga, O, and Eu distribution. The UV–visible diffuse reflectance spectroscopy (UV-DRS) showed a notable reduction in the bandgap as the Eu3+ concentration increased. The emission spectra of Eu: β-Ga2O3 microrods showed a narrow red emission at 612 nm (5D0 → 7F2), which relates to the 5D0 → 7Fj (j = 0, 1, 2, 3) energy level arising from an intra-4f transition of Eu3+ ions upon 394 and 465 nm excitation. The red emission was found to increase with Eu content up to 0.5 mol.%. A quenching of emission due to the multipole–multipole interactions was obtained beyond 0.5 mol.% of Eu. The absolute quantum yield (η) calculated for Eu: β-Ga2O3 (0.5 mol.%) was 3.82 %. The luminescence decay curve using the bi-exponential fit and the average lifetime (τ) of the Eu: β-Ga2O3 (0.5 mol.%) was found to be ∼0.172 ms. CIE chromaticity and correlated color temperature analyses of Eu:β-Ga2O3 microrods yielded a red emission with a superior color purity (93 %). The obtained results suggest that Eu:β-Ga2O3 (0.5 wt.%) microrods could be one of the potential candidates for red light sources.

Synthesis of Palladium Nanomaterials Using Plant Leaf Extract and their Enhanced Photocatalytic Activities against Organic Dyes

Aims and Objectives: This study aimed to carry out the green synthesis of palladium nanoparticles (Pd NPs) using the aqueous leaves extract of Eclipta alba. The appearance of a characteristic surface plasmon resonance peak at 410 nm confirmed the synthesis of Pd NPs. Method: The average particle sizes of 13 nm were observed by using the leaf concentrations of 10 mL with a certain amount of PdCl2 (0.001 M) at 25 ̊ C. The Pd NPs, as synthesized under the optimized conditions (10 mL extract + 60 ̊ C + 0.001 M PdCl2), were spherical in shape, small in size, and uniformly distributed, as depicted by HR-TEM images. Results: FTIR, XRD, DLS, and zeta potential further confirmed the formation of Pd NPs. The Pd NPs synthesized at optimized conditions exhibited strong catalytic activity in dye Eosin yellow, Rose Bengal, Tartrazine, and Ponceau S degradation by discoloration of dyes in 3 hrs. The removal of all dyes by the Pd NPs was optimized by varying specific operating parameters, such as initial dye concentration, solution pH, irradiation time, and temperature. Conclusion: This high activity of Pd NPs may be due to their small size, high dispersion, and surface- capping phytochemicals. result: Bio-fabrication of metallic Pd NPs using different plant extracts compared to other reducing agents is more scalable, rapid, and cost-effective for generating bulk nanoparticles. The phytochemical principles, such as phytoconstituents, reduce the PdCl2 to Pd NPs and are implicated in the capping and stability of the nanoparticles. Hence, the leaves of Eclipta alba have different polyols and are well known. Apart from this, hydroxyl groups in phenolic compounds may participate in the bio-reduction of PdCl2. Such compounds can chelate metal ions to form their quinones form, which is an intermediate palladium complex. Then, stabilization of the intermediate form and reduction of Pd2+ to Pd0 occurred due to free electrons or nascent hydrogen produced during the bio-reduction reaction. Finally, Pd-NPs were prepared due to the collision of neighboring Pd0 atoms. These significant conjugations exist in the keto-enol system within the quinone form of the compound.

On-site monitoring of L-adrenaline neurotransmitter in biological samples by chitosan oligosaccharide derived carbon dots

Carbon quantum dots (CDs) are fascinating fluorescent nanomaterial for spectrofluorimetry sensor applications, owing to the fact of its strong chemical stability, high quantum yield and high photostability. At this instance, we have developed the fluorescent sensing technique to detect the L-adrenaline (L-Adr) by nitrogen-doped carbon quantum dots as a sensing probe. The nitrogen-doped carbon dots was synthesized using chitosan oligosaccharide by hydrothermal method. The synthesized chitosan oligosaccharide derived CDs (COL-CDs) exhibits blue fluorescence under UV light and the size of the carbon quantum dots is 3.39 ± 0.08 nm calculated from HR-TEM image. The hormone called L-Adr found in the human body is crucial for controlling visceral processes. Utilizing the process of photo-induced electron transfer (PET), the previously mentioned COL-CDs have applied to sense the L-Adr. The sensing mechanism have explained clearly using Rehm-Weller equation by calculating ΔG. Tap water, blood serum, urine and adrenaline drug samples employed as real sample for the sensing L-Adr. A reagent free paper-based kit established for the purpose of on-site monitoring L-Adr. The smartphone’s colour picker software used to measure the RGB intensity from the paper-based kit.

High cycling stability polyaniline/carbon sphere/graphene ternary nanocomposite cathode material for asymmetric supercapacitors

Here, an asymmetric supercapacitor of the ternary nanocomposite polyaniline/carbon sphere/graphene (PANI/CS/G) is developed through a green strategy via the in-situ polymerization of aniline in carbon sphere/graphene (CS/G) dispersion prepared in a ball-mill method coupled with hydrothermal treatment. A strong interaction and thus the coverage of CS/G with PANI is revealed from the material characterization using XRD, FTIR and Raman spectroscopic techniques, and also from FESEM and HRTEM images. Uniform distribution of PANI over the CS/G provided an effective conducting network and enhanced diffusion of the electrolyte ions. PANI/CS/G showed a specific capacitance of 145.02 mF/cm2 at a current density of 1 mA/cm2 in 1 M H2SO4 originating from the electrostatic double layer capacitance behavior of the CS/G and pseudocapacitance of PANI. The fabricated asymmetric coin cell device with PANI/CS/G cathode and CS/G anode showed the highest areal capacitance of 320.78 mF/cm2 (@ 1 mA/cm2), a maximum energy density of 18.99 Wh/kg (@ 0.21 A/g), and a highest power density of 6088.48 W/kg (@ 8.68 A/g). The device displayed 101.6 % capacitance retention after 10000 cycles, indicating the effect of CS/G in diminishing the volume changes of PANI during the charge-discharge process, which usually affects the cyclic stability. By lighting a green LED, the real sense energy storage application of the supercapacitor is evaluated.

Nanostructured hexagonal S-doped CeO2 for effective Rh-B and MB dye degradation

The photocatalytic efficiency of CeO2−xSx (x = 0.05, 0.1, 0.2, 0.3, 0.5) hexagonal nanoparticles (HNPs) prepared through the hydrothermal method were tested by performing the degradation of Rhodamine-B and Methylene blue dyes under UV light irradiation. These compounds were thoroughly characterised using XRD, FESEM, EDX, HRTEM, XPS, ESR, FTIR, Raman, UV–vis DRS, BET and PL techniques. XRD analysis verified the cubic crystal structure of S-doped and pure CeO2 HNPs. HRTEM images clearly affirmed that S-doped CeO2 is made from HNPs. Over 94 % of Rh-B and 72 % of MB dyes were degraded by S-doped CeO2 for 180 min under UV light exposure, demonstrating its efficacy towards the photocatalytic activity (PCA). S-doped CeO2 HNPs have enhanced the PCA due to the reduction in the recombination rate of photo-generated electron-hole pairs, the rise in oxygen vacancy (Ov) and the narrowed optical band-gap. The photoluminescence findings clearly validated the increased PCA of S-doped CeO2. The scavenger tests confirmed the OH• and •O2− radicals participation in the quick degradation of both Rh-B and MB dyes.

Plant extract-mediated biosynthesis of sulphur nanoparticles and their antibacterial and plant growth-promoting activity

This study reports green synthesis of sulphur nanoparticles using sodium thiosulfate pentahydrate (Na2S2O35H2O) and Cannabis sativa leaf extracts. X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM) was employed to examine the crystallinity of the particles and morphological characteristics, proved both spherical and rod-shaped morphology of the S NPs having porous nature. The FTIR spectra revealed the interaction of the synthesized SNPs with the biomolecules present in the leaf extract. UV–VIS spectral investigations confirmed the production of SNPs from C. sativa leaf extract and that these SNPs can be used for visible region photocatalysis for the removal of pollutants from wastewater. Energy dispersive X-ray (EDX) spectrum of the SNP shows a single peak around 2.4 keV, confirmed S NPs purity. TEM image revealed the formation of mainly nanorods having a width of ∼20–25 nm and a length of 50–100 nm. Furthermore, some spherical particles (∼20–30 nm) were also formed. HRTEM image of the rod-shaped particles clearly shows the crystal fringe spacing of 0.38 nm. Further, disc diffusion method (DDM) was used to check the antibacterial activity of S NPs against gram-positive S. aureus (MTCC737) 18 ± 0.12 mm and gram-negative bacteria against E. coli (MTCC443) 21.5 ± 0.12 mm, A. salmonicida (MTCC1522) 19.1 ± 0.12 mm, K. pneumoniae (MTCC3384) 17.8 ± 0.10 mm. Among all the strains of bacteria, E. coli (MTCC443) showed a maximum zone of inhibition of 21.5 ± 0.12 mm and its antibacterial activity is somewhat like streptomycin sulfate. These SNPs also promote growth of C. sativa in pot experiment, resulting in a 30 % increase in biomass, 90 cm in shoot length and 28 cm in root length and higher fresh and dry weight (50g and 20g, respectively) with 1.0 mg mL−1 NPs treatment. In addition, SEM-EDX confirmed the accumulation of nanomaterial in plant leaves. This environmentally friendly approach to SNP synthesis using C. sativa extracts demonstrates both potent antibacterial properties and plant growth-promoting effects, making it a promising solution for agriculture and biomedicine.

S-scheme mechanism in the TiO2/Cu2O@Cu system toward selective degradation of an electron-rich dye pollutant under solar light

This research aims to reach a selective nanocomposite based on Cu and TiO2 nanoparticles (NPs) through a sol–gel followed by chemical reduction. Various methods such as XRD, SEM, TEM, HRTEM, BET, Raman, FTIR, DRS, XPS and PL analysis were used to characterize the prepared NPs. The reduced nature of Cu in nanocomposite was evidenced by its X-ray photoelectron spectral characteristics and its HRTEM image. Due to the presence of Cu NPs, light absorption in solar radiation by nanocomposite was considerably enhanced and caused more efficient charge carriers separation. A CCD was used to evaluate the photoactivity of the solar-driven photocatalyst by degrading methylene blue (MB) as a single model electron-rich organic pollutant. In optimal conditions, the highest photocatalytic activity reached 95.64 %. In this study, band structure and reactive species scavenging results confirmed an S-scheme mechanism for charge carrier transfer during photodegradation. The plasmonic S-scheme TiO2/Cu2O@Cu heterojunction photocatalyst exhibited remarkably strong photocatalytic selectivity toward MB in binary mixtures of MB with eosin B and rhodamine B. A preference for degradation of MB over safranin (Saf) is confirmed by the faster degradation rate of MB than that of Saf. S-scheme mechanism, Cu doping and dye sensitization all contributed to outstanding selective photodegradation performance.

Insight into deposition duration-varied crystallinity, optical parameters, morphology and electrical properties of solution-processed nanostructured CdSSe thin films

Nanostructured cadmium sulpho selenide (CdSSe) films have been grown onto glass substrates for different deposition durations via a facile solution-based method known as chemical bath deposition (CBD). XRD studies revealed that the crystallites in the films possessed hexagonal (wurtzite) structures with predominant orientation along the (002) plane. The crystallite size increased from ∼5.95 nm to ∼16.69 nm with the increase in deposition duration from 1 h to 4 h. The absorbance, transmittance and reflectance measurements were carried out. A transparency of ∼(50–80) % was obtained for the films. The direct optical energy band gap was found to decrease from 1.982 eV to 1.952 eV with the increment of deposition duration from 1 h to 4 h. SEM micrographs of the films revealed the presence of nano spherical-shaped grains with an average size ranging from ∼305 nm to ∼612 nm. HRTEM images illustrated the presence of compact nano-spherical grains and nano-crystallites distributed in random orientations. Raman spectroscopy divulged the presence of CdSe and CdS vibrational Raman modes and overtones in the films. PL spectra revealed a prominent red emission band along with weak luminescent bands in the yellow-red emission region. The presence of Cd–Se and Cd–S bonds in the films was validated using FTIR analysis. Electrical investigation revealed the linear current‒voltage relationship for the films with the rise in conductivity with deposition duration. Hence, deposition duration stands out as a vital parameter for modulating the properties of CdSSe thin films for use in photovoltaic devices and optoelectronics.

A highly efficient and stable PtNi bimetallic nanoparticles modified on Mo2C decorated N-doped carbon flowers catalysts for the remediation of environmental pollutants

The unregulated discharge of nitroaromatics (NAs) and organic dye contaminants into aquatic ecosystems is a growing global concern, highlighting the urgent need for the development of effective wastewater treatment technology. In this study, we prepared Mo2C decorated on N- doped carbon flowers supported with PtNi bimetallic (PtxNiy@Mo2C/NCF) nanoparticles using the self-polymerization of dopamine and followed by the chemical reduction methods. These catalysts, with varying Pt:Ni ratios, were designed for the highly efficient catalytic reduction of NAs and rhodamine b (RhB) under the mild reaction conditions. The HR-TEM images confirmed the formation of spherical PtNi bimetallic NPs with an average diameter of 1.68 ± 0.6 nm. The prepared PtxNiy@Mo2C/NCF catalysts exhibited significantly higher catalytic efficiency for 4-nitrophenol (4-NP) reduction compared to their respective monometallic counterparts using NaBH4. Particularly, the Pt0.75Ni0.25@Mo2C/NCF catalyst showed superior catalytic activity with the apparent rate constant (kapp: 0.6703 min−1) and TOF (17.0 × 10−7 mol mg−1 min−1) and high recyclability over eight consecutive recycles. Furthermore, the Pt0.75Ni0.25@Mo2C/NCF catalyst also exhibited high catalytic activity for other NAs and RhB dye reduction with excellent yields. This enhanced catalytic activity of Pt0.75Ni0.25@Mo2C/NCF catalyst could be ascribed to the synergistic effect of the bimetallic systems, leading to more efficient reactions. Additional experiments were conducted on a fixed bed reactor to demonstrate that the Pt0.75Ni0.25@Mo2C/NCF catalyst effectively reduce both 4-NP and RhB dye over 15 successive runs. This work may pave the way for using PtxNiy@Mo2C/NCF catalysts in various wastewater treatment applications.