Precursor Concentration Research Articles

Impact of deposition parameters on the optical properties of Fe2O3 thin films prepared by SILAR method

In order to explore the structures, morphology, and optical features of Fe2O3 nanofilms, the successive ionic layer adsorption and reactions (SILARs) technique was utilized to deposit the nanofilms onto glassy slides at varying concentrations of the precursor. Three precursor concentrations (0.025, 0.05 and 0.075) M were used. Analysis using X-ray diffraction (XRD) presented the crystalline structure of the Fe2O3 thin films. Field emission-scanning electron microscopy (FE-SEM) was used to evaluate the morphological features of the films. The results demonstrate that the surfaces of the films are nonporous and that there is a good distribution for spherical nanosize particles. The number of cycles is another important parameter that has been tested and its effect on the optical properties of prepared films was evaluated. The optical properties like optical absorption and energy gaps are affected directionally by changing the concentration and cycle numbers during the preparation. The latest objective of our study is to determine the role of precursor concentrations and deposition cycles in preparing thin films that have electronic applications such as sensors and solar cells.

Deciphering the application efficacy of titanium dioxide mediated calcareous nanocatalyst towards biodiesel production

The current investigation delved into the mechanistic insight, and cost-competent application of CaO-derived nanocataysts doped with TiO2 for enhanced biodiesel synthesis from castor oil. Calcium oxide-laden nanocatalysts were prepared via co-precipitation methodology with varying precursor and calcination temperatures concentrations. The engineered catalysts underwent characterization using XRD, SEM, particle size analysis, FTIR, EDX, UV-spectroscopy, and zeta potential measurements. Response surface methodology was implemented to create an experimental matrix for the transesterification. With methanol: oil ratio of 12:1, 5% catalyst weight, 2.25 h reaction interval, and a temperature of 60 °C, the utmost biodiesel yield achieved was 94.27%. Furthermore, the ester-enriched biodiesel was confirmed through GC-MS, 1H NMR, 13C NMR and FTIR analyses. Kinetic and thermodynamic studies revealed the endothermic and irreversible nature of the transesterification reaction. The fuel characteristics of the synthesized castor oil biodiesel are within acceptable ranges. The co-precipitation-derived nano TiO2@CaO catalyst validated impressive catalytic efficacy and stability, making it a proficient heterogeneous catalyst for augmented biodiesel manufacturing from castor oil. The projected expenses for 1 kg TiO2@CaO catalyst and 1 L COBD, obtained from cost assessments, were $ 6.37 and $ 0.578, respectively, showcasing their strong economic feasibility. Lastly, the study also offered future outlooks based on recognized gaps in the reported studies across a contemporary bibliometric investigation.

Branched polymer grafted graphene oxide (GO) as a 2D template for calcium phosphate growth

HypothesisGraphene Oxide (GO)-templated deposition of inorganic materials through synthesis on dispersed single sheets of GO is often complicated by the loss of the desired 2D morphology owing to the coagulation of GO sheets at high salt concentrations and non-templated homogenous nucleation. Modifying GO with anionic polymer is expected to solve both problems by i) enhancing electrostatic(steric) stabilization upon exposure to high concentrations of the ionic precursors, and ii) offering additional nucleation sites at the grafted anionic moieties to avoid homogeneous secondary nucleation. ExperimentsGO was grafted with branched copolymers of poly(ethylene glycol) methacrylate (PEGMA 500) and diethylene glycol dimethacrylate (DEGDMA) and ω-vinyl terminated methacrylic acid macromonomer (P(MAA)), the latter serving as an addition-fragmentation chain transfer agent. The colloidal stability of GO dispersions in water toward salt was evaluated before and after modification. Precipitation of calcium phosphate (CaP) was performed by incubating modified GO in the precursor solutions. The conditions were optimized to maximize the nucleation selectively onto GO without homogeneous CaP nucleation and coagulation of the GO-sheets. FindingsThe copolymer grafted GO-sheets shows superior colloidal stability when dispersed in water. No aggregation occurs in the incubating ionic CaP precursor solutions. The optimum templated deposition of CaP onto the GO sheets by precipitation is to add a second shot of precursors after the nucleation stage to obtain GO sheets fully decorated with calcium phosphate nanorods without self-nucleation. Via the careful design on the GO modification and incubation process, the growth of calcium phosphate nanorods were confined in the desired 2D order exclusively, hereby achieving the goal of an efficient GO-templated synthesis.

Tailoring the composition of a non-noble, Cubic Shaped MnSn(OH)6 Bi-functional electrocatalysts for methanol and urea oxidation reactions in alkaline solutions

A systematic study of the effect of Sn-precursor concentration on the composition of (MnSn(OH)6) is carried out, and the samples' structural, morphological, and electrochemical variations are investigated. Four different SnCl2·5H2O precursor concentrations (5, 10, 20, and 40 mM) are varied to synthesize MnSn(OH)6 electrocatalysts, denoted as MS-1, MS-2, MS-3, and MS-4, respectively, using a hydrothermal method. All four samples' crystal structure and chemical states are identified using X-ray diffraction analysis and X-ray photoelectron microscopy. Morphological studies are carried out using scanning electron and transmission electron microscopy studies. The electrocatalytic performance and the stability of the synthesized samples are evaluated using cyclic voltammetry and chronoamperometry. Among the samples, MS-3, which has an optimized ratio of Mn/Sn, displayed the highest current density values of 80.3 mA g−1 and 84.7 mA g−1 at a higher potential of 0.7 V for the urea oxidation reaction in the presence of 0.33 M urea + 1.0 M KOH and for the methanol oxidation reaction in the presence of 0.5 M methanol + 1.0 M KOH, respectively. This intrinsic activity of MS-3 samples is due to its more significant electrochemically active surface area value of 208 mF cm−2, primarily because of the dominance of Mn3+ on the surface. Furthermore, MS-3 displayed reduced overpotential, as evidenced by the onset potential of 1.45 (V vs RHE) @ 10 mA cm−2, indicating enhanced electrocatalytic performance. These findings highlight the importance of tuning the Mn/Sn metal ratio to design and develop cost-effective non-precious electrocatalysts for urea and methanol oxidation reactions.

Size-Dependence of the Electrochemical Activity of Platinum Particles in the 1 to 2 Nanometer Range

Monodisperse Pt nanoparticles supported on carbon (Pt/C) were prepared via an impregnation method. By changing the concentration of the platinum precursor in the initial reagent mixture, the average particle size (d) could be controlled to within a narrow range of less than 2 nm. The specific activity (SA) of these materials, when applied to the oxygen reduction reaction (ORR), increased rapidly with d in the range below 1.8 nm, with a maximum SA at d = 1.3 nm. This value is approximately four times that of a commercial Pt/CB catalyst. The electrochemical active area, ECAA (electrochemical surface area (ECSA)/specific surface area (SSA) × 100), decreased drastically from 100% with decreases in d below 1.3 nm. In this study, we present a correlation between SA and ECAA as a means of determining the appropriate d for polymer electrolyte fuel cells (PEFCs) and propose an optimal size.

State of the art on plasma-liquid route synthesis monometallic Au, bimetallic Au/Ag core–shell and alloy nanoparticles: Toxicological, сanalytical, antimicrobial activity for environmental control

Nanoparticles (Au monometallic, bimetallic structures Au-Ag alloy and Aucore – Agshell) were synthesized in aqueous solutions with traditional capping agent - sodium citrate, using a one-step (for monometalic and alloy structure) and two–step (for Aucore – Agshell NPs) liquid-phase anode type plasma process. The effects of parameters of synthesis: precursors concentration, the solution plasma process discharge time, molar contents Ag+/Au3+ for alloy NPs, and molar content of Ag+ for Au core NP to the characteristics of the synthesized NPs, including average size (the size distribution, polydispersity index), optical absorption properties ect.) were investigated. The synthesized nanoparticles have the following characteristics: Au NPs with λ=530–540 nm and d = 5–60 nm, the monometalic structure; Ag/Au with the λ=410–530 nm and d = 28–80 nm, bimatalic strucrure of alloy; NPs with significant blue-shift the λ=530→410 nm, depending the shell thickness (the thickness of the deposited Ag shells varied from ∼1–15 nm) and d = 21–35 nm for NPs core(Au)–shell(Ag). TEM images clearly confirm the effectiveness of a one- and two-step plasma-liquid treatment for the synthesis of monometallic Au NPs and the two different structures of the NPs (bimetallic structures Au-Ag alloy and Aucore@– Agshell). The effect of nanoparticle structure on antimicrobial and catalytic properties relative to their respective monometallic counterparts was demonstrated. Among the different investigated structure NPs only for bimetallic core−shell structured AucoreAgshell NPs was found strong synergistic effect for antimicrobial and catalytical activity.

Flame synthesis of nanoparticles based on high flux electrostatic atomization burner.

This study presents an innovative electrostatic spray flame synthesis (ESFS) reactor that combines the advantages of electrostatic spray and flame synthesis for precise spray control and efficient single-step continuous synthesis. To overcome the limitations of conventional ESFS systems, which often suffer from low atomized precursor flux, we successfully demonstrated a high-flux disk electrostatic atomizer coupled low-swirl flame reactor, achieving a precursor flux of up to 30 ml/h about 30 times higher than that of typical ESFS devices. The atomized precursor being rapidly carried away from the burner is undergoing high-temperature pyrolysis and particle formation through lifted premixed turbulent flames. The ESFS system provides extensive control over parameters such as flame temperature, equivalence ratio, residence time, initial droplet sizes, and precursor concentrations. For illustrative purposes, the ESFS system was utilized to synthesize silica nanoparticles, demonstrating the capability of synthesizing nanoparticles with various properties. By manipulating the collection position and height, the particle size has made a substantial leap from the nanoscale to the micrometer level. This remarkable achievement underscores the system's enormous potential for precise particle size regulation and one-step synthesis of complex structured thin films.

Study on the Effects of Precursor Concentration and Annealing Process of In2O3 thin Films Prepared by Sol-gel Method

Study on the Effects of Precursor Concentration and Annealing Process of In2O3 thin Films Prepared by Sol-gel Method

Effect of Precursors Concentration on The Optical and Photoelectrochemical Properties of Bi₂S₃/TiO₂ Nanotubes Arrays Photoanode Synthesized by the SILAR Technique

The use of robust solar energy-driven photocatalysis materials to address the global energy and environmental crisis has gained significant attention in recent years. However, the wide band gaps in many robust semiconductor photocatalysts hinder their absorption of visible light from the solar spectrum. To address this issue, the modification of the large band gap semiconductor with the lower band gap material using the Successive Ionic Layers Adsorption and Reaction (SILAR) technique has emerged as an economical, accessible, and reproducible method for depositing nanoscale materials onto semiconductor substrates. This research aims to know how the concentration variation of cation and anion precursors in the SILAR technique affects the optical and photoelectrochemical properties of the resulting composite materials. Bi₂S₃ serves as a modifier for TiO₂ nanotube arrays (NTAs). The result shows that the cation-anion concentration ratio of 1:1.5 mM with five SILAR cycles gives the best photoelectrochemical performance, with a stable current density of 0.12 mA/cm², compared to pristine TiO₂ NTAs the current density of Bi₂S₃/TiO₂ NTAs is 15-fold. In addition, at each variation, the concentration ratio of cation and anion precursors decreases bandgap energy with each increase in the SILAR cycle.

Impact of nanoscale Cu (I) precursors prepared by solution process on large-area CdTe solar cells

In recent years, the study of Cu (Ӏ) precursors in high-performance CdTe thin-film solar cell devices has received increasing attention. However, few studies have been reported on nanoscale Cu (I) precursors in large-area CdTe devices (≥1 cm2). Here, three different Cu (Ӏ) nano precursors have been rapidly prepared by solution method (CuCl ethanol solution, CuI acetonitrile solution, and CuSCN aqueous ammonia solution) and their effects on the performance of commercial large-area CdTe thin-film solar cells have been investigated. The results show that the distribution amount and uniformity of the nano precursor particles on the CdTe back surface have a large impact on the device performance. The CuCl nanoparticles are more uniformly distributed and the device performance is more excellent. CuI nanoparticles easily formed clusters at grain boundaries. Denser distribution of CuSCN nanoparticles. The thermal diffusion conditions (temperature, time and precursor concentration) have a significant effect on the device performance, but the most reasonable thermal diffusion conditions tend to be the same for all devices. This suggests that the thermal diffusion conditions are determined by the nature of the CdTe absorber layer itself and are not interfered by different nano precursors.

Source apportionment and formation of warm season ozone pollution in Chengdu based on CMAQ-ISAM

In this study, the WRF-CMAQ model integrated with BEM urban canopy model was used to simulate the concentrations of Ozone (O3) and its precursors, NOx and VOCs, in warm season of Chengdu, conduct source apportionment and formation analysis. The results show that the O3 in Chengdu exhibits a west-high/east-low spatial pattern, attributable to nearly 40% contribution from boundary sources representing the transport role of the Sichuan Basin, regional sources from districts emitting high precursor concentrations, and increasing biogenic contributions from western areas due to rising BVOCs emissions during the warm season. NOx from traffic and VOCs from industrial sources, both prevalent in Chengdu's high urban density areas, chemically react to form O3, making these sectors primary contributors to O3. NOx photochemical reactions producing O3 occur at 150 m–2500 m with peak generation rates of 10 μg/(m3·hr). Ground-level NO titration removal is most significant during heavy traffic (14:00–21:00), ranging from −70 to −200 μg/(m3·hr). O3 is replenished through similar rates of daytime vertical diffusion and nighttime horizontal advection, correlating with urban density across regions. Controlling Chengdu's warm season O3 requires focusing on long-distance external transport and regional precursor emission reductions, with strategies tailored to local urban characteristics.

Effect of precursor concentration, surfactant and temperature on the size, morphology and nanostructure of zero-valent iron nanocrystals synthesised by a polyol route

Iron metal nanoparticles, due to their magnetic properties, reducing power and low toxicity, have numerous applications not only in groundwater and contaminated soil remediation but also in biomedicine as contrast agents in magnetic resonance imaging. However, obtaining this nanomaterial involves the use of strongly reducing, polluting and expensive reagents and high temperatures. Herein, the use of ethylene glycol and diethylene glycol in a strong alkaline medium that allows the direct reduction of iron(II) salts to iron(0) in the absence of any added reducer has been analysed for preparation of well-defined nanoparticles. The key roles of the polyhydroxylated surfactants (D-mannitol, D-mannose, polyvinyl alcohol and polyvinyl pyrrolidone) were identified, and their efficiencies were evaluated. In addition, conclusions have been drawn regarding the existence of a minimum temperature required for the reduction of the precursor, as well as the observation that the size of the nanoparticles increases with reaction temperature. The main result is that by combining surfactants and controlling the reaction temperature, pure cubic iron(0) nanoparticles smaller than 100 nm were obtained, thereby reducing the formation of hydroxylated by-products. The high reactivity, high magnetic response, long-term stability and small size of the iron nanoparticles produced in this work will allow their use in various applications.

NiFe2O4/N-CNT mediated peroxydisulfate activation via radical and non-radical pathways for water purification

Metal oxide catalysts can significantly enhance the efficiency of the peroxydisulfate (PDS) activation to decompose refractory organic pollutants, and advanced strategies for improving the activation performance of the catalysts include exposing more metal active sites, optimizing the electronic structure, and enhancing cycling stability. Herein, a novel NiFe2O4/N-CNT composite was synthesized by the simple hydrothermal process. Additionally, the performance of the prepared catalysts can be adjusted by varying the content of N-doped precursors. The prepared NiFe2O4/N-CNT nanostructures had excellent activation properties for PDS, leading to sufficient free radicals and non-free radicals to degrade dyes. The system required only 0.07 g·L−1 of catalyst and 0.1 g·L−1 of PDS to degrade 100 mL (0.1 g·L−1) of reactive brilliant blue KN-R, and the degradation rate could reach 93 % within 30 min. The pH range was also wider, with excellent degradation under strong acidic conditions (pH=1). Moreover, it was highly adaptable to the common anions (Cl-, NO3-) and natural organic humic acid (HA) in the water body. This study expands the idea of the activation mechanism of peroxydisulfate (PDS) and successfully prepares catalysts for the effective degradation of organic dyes, showing the promising application of synergistic interaction between radicals and non-radicals in the degradation of persulfate.

Flower-Branch-Like carbon Microtube/Vanadium Selenide: A highly efficient electromagnetic wave absorbing composite

The unique layered structure and adjustable band gap of transition metal dichalcogenides (TMDs) have prompted extensive investigations into their potential for electromagnetic wave absorption (EWA). Vanadium selenide (VSe2), a notable representative of TMDs, has a larger interlayer spacing (6.1 Å) and higher conductivity (1 × 10-3 S/m), which has high advantageous in EWA applications. However, the existing research on the use of VSe2 for EWA remains relatively limited. Herein, a flower-branch-like carbon microtube/vanadium selenide (CMT/VSe2) composite was successfully synthesized via a facile solvothermal method. This composite material is composed of flower-like VSe2 nanostructures integrated with carbon microtubes. Importantly, the EWA properties of this composite can be effectively tailored by adjusting the concentration of the VSe2 precursor. The CMT/VSe2 composite exhibited a remarkable minimum reflection loss (RL) of −60.54 dB in the Ku-band, with a matching thickness of 2.27 mm. Moreover, the effective absorption bandwidth reached 6.38 GHz. These results demonstrate the great potential of this CMT/VSe2 composite material as a highly efficient EWA material. Furthermore, this work broadens the application of two-dimensional TMDs in the area of EWA.

Strontium ferrite oxide (Sr3Fe2O7) decorated TiO2 photoanode improves the photo-absorption and photoelectrochemical cell efficiency

In this study, a coating of strontium ferrite oxide (SFO), Sr3Fe2O7, on TiO2 demonstrated an enhancement in photoelectrochemical cell (PEC) performance. Pure TiO2 and SFO decorated TiO2 (SFO/TiO2) were synthesized using the hydrothermal method. The concentration of SFO precursor in this study varied between 0.5, 1.0, and 1.5 mmol. Most of the optimized SFO concentration showed the better Applied Bias Photon-to-current Efficiency than the pure TiO2. The structure, chemistry, and surface morphology of TiO2 and SFO/TiO2 materials were investigated using several techniques, including X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The UV–visible spectra revealed that SFO was able to reduce the energy band gap of pristine TiO2 from 3.09 to 2.55 eV. The photoluminescence spectroscopy displayed that almost SFO/TiO2 materials exhibited the lower recombination time than the pristine TiO2. Moreover, 1.0 mmol of SFO/TiO2 exhibited the highest photocurrent density, at approximately 12.5 μA/cm2, which was 12 times greater than pure TiO2. The Mott-Schottky analysis revealed the energy band edge of SFO and the TiO2 was well alignment. Therefore, SFO plays a crucial role in improving the photo-absorption efficiency of PEC cell. The enhanced PEC performance was achievable due to the materials’ tailored light response.

The Oscillatory Behaviour of Cu-ZSM-5 Catalysts for N2O Decomposition: Investigation of Cu Species by Complementary Techniques.

Copper-exchanged ZSM-5 (Cu-ZSM-5) is a promising catalyst thanks to the Cu redox pair. A particular feature of this material consists in the presence of spontaneous isothermal oscillations which take place during N2O decomposition reaction, depending on the operating conditions. In the present work, a set of five Cu-ZSM-5 catalysts was synthesised by three procedures and three different copper precursor concentrations: i) wet impregnation, ii) single ion exchange, and iii) double ion exchange. Catalytic tests revealed that the ion-exchanged samples exhibit a low catalytic activity and no oscillatory behaviour, except for the twice-exchanged sample which achieves an average N2O conversion of 26 % at 400 °C. Conversely, the impregnated samples reach higher levels of N2O conversion (66 % for Cu5ZSM5_WI and 72 % for Cu10ZSM5_WI) and demonstrate a similar oscillating pattern. Further investigations disclosed that the most active catalysts, characterised by the presence of oscillatory behaviour, have more abundant and easily reducible copper species (ICP, EDX and H2-TPR) which interact better with the zeolitic support (FT-IR). Catalytic tests under a long time on stream (TOS) suggest that either self-organised patterns or deterministic chaos can be achieved during the reaction, depending on the operating conditions, such as temperature and contact time.

Comparative Effect of Antioxidant and Antibacterial Potential of Zinc Oxide Nanoparticles from Aqueous Extract of Nepeta nepetella through Different Precursor Concentrations.

Antibiotic resistance is a global health crisis caused by the overuse and misuse of antibiotics. Accordingly, bacteria have developed mechanisms to resist antibiotics. This crisis endangers public health systems and medical procedures, underscoring the urgent need for novel antimicrobial agents. This study focuses on the green synthesis of ZnO nanoparticles (NPs) using aqueous extracts from Nepeta nepetella subps. amethystine leaves and stems, employing different zinc sulfate concentrations (0.5, 1, and 2 M). NP characterization included transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD), along with Fourier transform infrared spectroscopy (FTIR) analysis. This study aimed to assess the efficacy of ZnO NPs, prepared at varying concentrations of zinc sulfate, for their capacity to inhibit both Gram-positive and Gram-negative bacteria, as well as their antioxidant potential using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. SEM and TEM results showed predominantly spherical NPs. The smallest size (18.5 ± 1.3 nm for leaves and 18.1 ± 1.3 nm for stems) occurred with the 0.5 M precursor concentration. These NPs also exhibited remarkable antibacterial activity against both Gram-positive and Gram-negative bacteria at 10 µg/mL, as well as the highest antioxidant activity, with an IC50 (the concentration of NPs that scavenge 50% of the initial DPPH radicals) of 62 ± 0.8 (µg/mL) for the leaves and 35 ± 0.6 (µg/mL) for the stems. NPs and precursor concentrations were modeled to assess their impact on bacteria using a 2D polynomial equation. Response surface plots identified optimal concentration conditions for antibacterial effectiveness against each species, promising in combating antibiotic resistance.

Field emission from two-dimensional (2D) CdSSe flake flowers structure grown on gold coated silicon substrate: An efficient cold cathode.

Field emission finds a vital space in numerous scientific and technological applications, including high-resolution imaging at micro- and nano-scales, conducting high-energy physics experiments, molecule ionization in spectroscopy, and electronic uses. A continuous effort exists to develop new materials for enhanced field emission applications. In the present work, two-dimensional (2D) well-aligned CdSSe flake flowers (CdSSe-FFs) were successfully grown on gold-coated silicon substrate utilizing a simple and affordable chemical bath deposition approach at ambient temperature. The time-dependent growth mechanism from nanoparticles to FFs was observed at optimized parameters such as concentration of precursors, pH (~11), deposition time, and solution temperature. The crystalline nature of CdSSe-FFs is confirmed by high-resolution transmission electron microscopy (HRTEM) results, and selected area electron diffraction (SAED) observations reveal a hexagonal crystal structure. Additionally, the CdSSe-FFs thickness was confirmed by TEM analysis and found to be ~20-30 nm. The optical, photoelectric, and field emission (FE) characteristics are thoroughly explored which shows significant enhancement due to the formation of heterojunction between the gold-coated silicon substrate and CdSSe-FFs. The UV-visible absorption spectra of CdSSe-FFs show enhanced absorption at 700 nm, corresponding to the energy band gap (Eg) of 1.77 eV. The CdSSe-FFs exhibited field emission and photosensitive field emission (PSFE) characteristics. In FE study CdSSe-FFs shows an increase in current density of 387.2 μ A cm-2 in an applied field of 4.1 V m-1 which is 4.08 fold as compared to without light illumination (95.1 μ A cm-2). Furthermore, it shows excellent emission current stability at the preset value of 1.5 μA over 3 h with a deviation of the current density of less than 5% respectively. RESEARCH HIGHLIGHTS: Novel CdSSe flake flowers were grown on Au-coated Si substrate by a cost-effective chemical bath deposition route. The growth mechanism of CdSSe flake flowers is studied in detail. Field emission and Photoluminescence study of CdSSe flake flowers is characterized. CdSSe flake flowers with nanoflakes sharp edges exhibited enhanced field emission properties.

Exploring the effect of morphology on electrochemical performance of nickel and cobalt metal-organic frameworks and their derivatives for supercapacitor and hydrogen evolution

This study explores the novel approach of investigating the use of binder-free nickel and cobalt metal-organic frameworks and their metal oxide derivatives in 1D, 2D, and 3D morphologies on Ni foam for applications in supercapacitors and hydrogen evolution. This research work involves changing parameters like precursor concentration, organic linkers, and reaction time, leading to the formation of stable one-, two-, and three-dimensional NiO and Co3O4 nanostructures. The morphologies of pristine MOFs and their corresponding oxides were comprehensively verified through FESEM analysis. Significantly, the materials with two-dimensional growth exhibited superior electrochemical performance in supercapacitors and good electrocatalytic performance in hydrogen evolution reaction when compared to their one-dimensional and three-dimensional counterparts. Among them, 2D NiO demonstrated exceptional performance as a supercapacitor electrode, with a specific capacity of 688.13 C g−1 (1376.26 F g−1) at 1 A g−1, surpassing 1D and 3D NiO nanostructures. It also demonstrated good stability by retaining 93.1 % of its initial capacity after 5000 cycles at 10 A g−1. The assembled asymmetric supercapacitor (ASC) achieved a high energy density of 65.27 Wh kg−1 at 375 W kg−1, maintaining 33.18 Wh kg−1 even at 7500 W kg−1. It also maintained 87.8 % retention of its initial capacity up to 5000 cycles at 10 A g−1. Furthermore, when tested for HER, all oxides exhibited better performances with specifically 2D NiO exhibiting good catalytic performance, reaching 10 mA cm−2 at a low overpotential of 129 mV (vs. RHE) and displaying remarkable stability over 24 h. This study upholds the superiority of two-dimensional sheet-like structures with interconnected network of nanoparticles in electrochemical and electrocatalytic performance compared to one-dimensional rod-like and three-dimensional pyramid-like structures.

Serum concentrations of legacy, alternative, and precursor per- and polyfluoroalkyl substances: a descriptive analysis of adult female participants in the MIREC-ENDO study

BackgroundSeveral legacy and emerging per- and polyfluoroalkyl substances (PFAS) have been regulated around the world. There is growing concern over the proliferation of alternative PFAS, as well as PFAS precursors. Biomonitoring data for PFAS are critical for assessing exposure and human health risk.MethodsWe collected serum samples from 289 adult female participants in a 2018–2021 follow-up study of the Maternal-Infant Research on Environmental Chemicals (MIREC) Canadian pregnancy cohort. Samples were analyzed for 40 PFAS using ultra-performance liquid chromatography–tandem mass spectrometry. For those compounds with > 50% detection, as well as the sum of these compounds, we describe serum concentrations and patterns of exposure according to sociodemographic and obstetrical history characteristics.Results17 out of 40 PFAS were detected in > 50% of samples with 7 of these detected in > 97% of samples. Median [95th percentile] concentrations (µg/L) were highest for PFOS (1.62 [4.56]), PFOA (0.69 [1.52]), PFNA (0.38 [0.81]), and PFHxS (0.33 [0.92]). Geometric mean concentrations of PFOA and PFHxS were approximately 2-fold lower among those with more children (≥ 3 vs. 1), greater number of children breastfed (≥ 3 vs. ≤ 1), longer lifetime duration of breastfeeding (> 4 years vs. ≤ 9 months), and shorter time since last pregnancy (≤ 4 years vs. > 8 years). We observed similar patterns for PFOS, PFHpS, and the sum of 17 PFAS, though the differences between groups were smaller. Concentrations of PFOA were higher among “White” participants, while concentrations of N-MeFOSE, N-EtFOSE, 7:3 FTCA, and 4:2 FTS were slightly higher among participants reporting a race or ethnicity other than “White”. Concentrations of legacy, alternative, and precursor PFAS were generally similar across levels of age, education, household income, body mass index, and menopausal status.ConclusionsWe report the first Canadian biomonitoring data for several alternative and precursor PFAS. Our findings suggest that exposure to PFAS, including several emerging alternatives, may be widespread. Our results are consistent with previous studies showing that pregnancy and breastfeeding are excretion pathways for PFAS.