The synthesis of efficient hydrogen evolution reaction (HER) electrocatalysts is challenging for industrial-scale hydrogen generation by water splitting. Since their discovery in 2011, MXenes have ...been extensively investigated for their use in various energy applications as they possess sheet-like morphology that provides more active surface area and facilitates fast ion transfer. This work utilizes a facile hydrothermal treatment to fabricate palladium-modified MXene nanoflowers (nPdNFs). Chemical and morphological analysis of these synthesized nPdNFs shows that nPds have been successfully incorporated in MXene nanoflowers and act as an excellent support material for nPds. The effect of temperature and the thermal decomposition properties of the synthesized material were investigated by calcining it at different temperatures like 200, 300, and 400 °C in a flow of N2 gas. It is observed that nPdNFs-3 (calcined at 300 °C) exhibits maximum active catalytic sites for HER because its porous morphology supports rapid ion transportation. The electrochemical active surface area (ECSA) for all three materials was evaluated, among which nPdNFs-3 demonstrated the highest ECSA value, corroborating its HER activity and depicting a current density of 10 mA cm−2 at a low overpotential of 149 mV, with a Tafel slope of 96 mV dec–1 in 0.5 M H2SO4. The fabricated nanostructured material highlights ceaseless efforts and paves the way for developing MXenes and related materials, which can be employed in the energy conversion and storage sector.
Two-dimensional MXene with layered structure has recently emerged as a nanomaterial with fascinating characteristics and applicability. Herein, we prepared the newly modified magnetic MXene (MX/Fe
3
...O
4
) nanocomposite using solvothermal approach and investigated its adsorption behavior to study the removal efficiency of Hg(II) ions from aqueous solution. The effect of adsorption parameters such as adsorbent dose, time, concentration, and pH were optimized using response surface methodology (RSM). The experimental data fitted well with quadratic model to predict the optimum conditions for maximum Hg(II) ion removal efficiency which were found to be at adsorbent dose 0.871 g/L, time 103.6 min, concentration 40.17 mg/L, and 6.5 pH respectively. To determine the adequacy of the developed model, a statistical analysis of variance (ANOVA) was used, which demonstrated high agreement between the experimental data and the suggested model. According to isotherm result, the experimental data were following the best agreement with the Redlich-Peterson isotherm model. The results of the experiments revealed that the maximum Langmuir adsorption capacity of 699.3 mg/g was obtained at optimum conditions, which was closed to the experimental adsorption capacity of 703.57 mg/g. The adsorption phenomena was well represented by the pseudo-second-order model (
R
2
= 0.9983). On the whole, it was clear that MX/Fe
3
O
4
has lot of potential as a Hg(II) ion impurity removal agent in aqueous solutions.
Electrocatalytic water splitting provides a sustainable method for storing intermittent energies, such as solar energy and wind, in the form of hydrogen fuel. However, the oxygen evolution reaction ...(OER), constituting the other half-cell reaction, is often considered the bottleneck in overall water splitting due to its slow kinetics. Therefore, it is crucial to develop efficient, cost-effective, and robust OER catalysts to enhance the water-splitting process. Transition-metal-based coordination polymers (CPs) serve as promising electrocatalysts due to their diverse chemical architectures paired with redox-active metal centers. Despite their potential, the rational use of CPs has faced obstacles including a lack of insights into their catalytic mechanisms, low conductivity, and morphology issues. Consequently, achieving success in this field requires the rational design of ligands and topological networks with the desired electronic structure. This study delves into the design and synthesis of three novel conjugated coordination polymers (CCPs) by leveraging the full conjugation of terpyridine-attached flexible tetraphenylethylene units as electron-rich linkers with various redox-active metal centers Co(II), Ni(II), and Zn(II). The self-assembly process is tuned for each CCP, resulting in two distinct morphologies: nanosheets and nanorings. The electrocatalytic OER performance efficiency is then correlated with factors such as the nanostructure morphology and redox-active metal centers in alkaline electrolytes. Notably, among the three morphologies studied, nanorings for each CCP exhibit a superior OER activity. Co(II)-integrated CCPs demonstrate a higher activity between the redox-active metal centers. Specifically, the Co(II) nanoring morphology displays exceptional catalytic activity for OER, with a lower overpotential of 347 mV at a current density of 10 mA cm–2 and small Tafel slopes of 115 mV dec–1. The long-term durability is demonstrated for at least 24 h at 1.57 V vs RHE during water splitting. This is presumably the first proof that links the importance of nanostructure morphologies to redox-active metal centers in improving the OER activity, and it may have implications for other transdisciplinary energy-related applications.
Fluorescent graphene quantum dots (GQDs) are nanomaterials which possess unique properties that show great potential in different applications. In this work, GQDs were synthesized using graphene ...oxide (GO) as precursor via thermal treatment at high temperature. The obtained GQDs were highly fluorescent and were suitable for the determination of heavy metal ions. X-ray diffraction, FTIR spectroscopy, and UV visible spectroscopy confirm the formation of GQDs. TEM images show that formed GQDs have size ranging from 2 to 10 nm. Emission profile of aqueous GQDs was taken by exciting GQDs at different wavelength. The intensity of GQDs remains the same for 4–5 months. Furthermore, as prepared, GQDs were used for selective recognition of Fe
3+
, Pb
+2
, and Cr
3+
from the bunch of different metal ions in aqueous media. Lower limit of detection obtained for Fe
3+
, Cr
3+
and Pb
2+
using GQDs were 50, 100 and 100 nM, respectively, which indicates that the GQDs can be utilized as a promising material for sensing of the heavy metal ions.
Graphical abstract
The main objective of this study was to assess the continuous electrocoagulation process effectiveness for removing fluoride from potable water. The effect of different parameters like applied ...potential, electrode spacing, and feed flow rate was optimized for the continuous removal of fluoride from potable water. Response surface methodology (RSM) was used to examine the impact on essential operational factors such as voltage, concentration, and pH for fluoride removal as a response. The results demonstrate that all the parameters had a significant effect on removal efficiency. The quadratic model accurately predicted the optimal parameters for maximal fluoride removal efficiency with the association of desirability 1.0, which was discovered to be voltage 2.38 V, feed concentration 5.52 mg/L, and pH 6.45. According to the analysis of variance,
R
2
of the proposed quadratic model is higher (0.9877). Moreover, the difference between the predicted
R
2
of 0.9258 and the adjusted
R
2
of 0.9767 was less than 0.2. The model adequacy was also studied based on residual plot, perturbation plot, and box-cox plot. The RSM was best modeling techniques use to predict data than the multilayer perceptron and linear regression due to high accuracy. Finally, the generated flocs were characterized by scanning electron microscopy, energy-dispersive X-ray, X-ray diffraction, and Fourier transform infrared spectroscopy instrumental techniques. The outcomes demonstrate that a newly designed continuous electrocoagulation process is a promising alternative for the removal of fluoride from potable water.
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•Nano-alumina wrapped carbon microspheres have been synthesised successfully.•Al-CMs are able to remove more than 98% of F− and As(V) under wide pH range.•Ultrahigh removal of As(V) ...and F− in the presence of interfering ions.•High adsorption capacities of 68 and 371.1 mg/g for As(V) and F− respectively.•Reusability of adsorbent without compromising the efficiency.
Materials with ultrahigh adsorption competences are extensively required for effective wastewater remediation. Unfortunately, leaching and agglomeration of nanomaterial-based adsorbents is a common problem to be resolved. Carbon-based hybrid nanocomposite showing enormous capability in the field of wastewater treatment. Arsenic and fluoride in water have unpropitious effects on people’s health, and remediation of these ions through adsorption is one of the foremost challenges and high priority to the research. The present study deals with fabricating a novel composite using alumina wrapped carbon microspheres (Al-CMs) with high adsorption capacities and investigating the mechanism for removing pentavalent arsenic/arsenate (As(V)) and fluoride (F−) at the molecular level. The maximum adsorption capacities for As(V) and F− calculated from the Langmuir model are 68 and 371.1 mg/g, respectively, comparatively higher than other reported nano-adsorbents. Under optimized conditions, Al-CMs are able to remove more than 98% of F− and As(V) under wide range of pH (2–12). Further, the interaction energy of Al-CMs with F− and As(V) was examined using density functional theory (DFT). The reported work exhibits a feasible adsorbent for removing F− and As(V) from the wastewater.
Consumption of As(III) in drinking water is a severe problem, and more than 180 million people are suffering worldwide. Therefore, developing an affordable technique to remove As(III) from drinking ...water is essential to protect human health. In this work, we report chitosan‐iron oxide‐graphene oxide composite beads (GO‐BDs) for the removal of As(III) from the drinking water. The incorporation of chitosan and graphene oxide (GO) provides better physical strength and stability to the GO‐BDs. Prepared GO‐BDs were characterized using different characterization techniques. X‐Ray diffraction (XRD) spectra show the iron oxide nanoparticles were successfully linked with graphene oxide. The size of the beads confirmed by scanning electron microscopy (SEM) and found to be ~1 mm. Elemental mapping of beads show the uniform dispersion of GO/iron oxide on the surface of the beads. The adsorption of As(III) occurs rapidly and attain equilibrium condition in <6 h after removing As(III) from the water within the permissible limit. Effect of water pH, time, temperature, adsorbent dosage, and concentration of the dose have been studied in detail for arsenic removal. Coexisting ions show negligible influence on As(III) removal. Langmuir and Freundlich isotherms were also examined. This study provides the application of GO‐BDs for As(III) removal from contaminated drinking water.
Removal of Arsenic from drinking water using composite magnetic beads.
Brightly fluorescent Carbon Dots (CDs) were synthesized by green hydrothermal method using commonly available biomass (Aloe vera) as carbon precursor. Their physiochemical and optical ...characterization was done by standard microscopic and spectroscopic techniques. Photophysical features of their aqueous dispersion were investigated in detail. The influence of wide pH range (2–12), high ionic load (2M) and temperature on their photoluminescence behavior was investigated. Their in-vitro cytotoxicity examination was conducted on Human Cervical Cancer Cells (HeLa) using MTT assay. Testing of their ion-recognition property for common metal ions was done in aqueous medium. These CDs exhibited preferential interaction with Fe3+ over other tested metal ions, without any functionalization. Interaction between CDs and Fe3+ was analyzed in the light of Density Functional Theory (DFT). The work demonstrates that these CDs are acting as nanoprobe for Fe3+ and sensing it at ultra-trace level (5 nM).
Carbon dots; Photoluminescence; Iron; nanosensor; Quenching.
Graphene quantum dots (GQDs) have been prepared from graphene oxide (GO) and characterized by standard analytical techniques. The size of the prepared GQDs ranges from 2-10 nm. Aqueous dispersion of ...GQDs exhibited excitation-dependent emission behavior. Emission intensity of the aqueous dispersion found stable for the examined duration of about four months. GQDs exhibited selective recognition of Fe
3+
and Cr
3+
out of various common ions such as alkali, alkaline-earth and transition metal ions in aqueous medium through fluorescence quenching. The lower limit of detection of Fe
3+
is 1 µM and that of Cr
3+
is 4 µM.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Water‐dispersible and fluorescence‐stable carbon quantum dots (CQDs) have been synthesized at gram scale using pyrene as carbon precursor by employing the bottom‐up approach. X‐ray diffraction, FTIR, ...Raman spectroscopy and UV visible spectroscopy confirm the formation of CQDs. TEM images shows that size of the CQDs ranges from 2 to 5 nm. A detailed study of their optical and fluorescence characteristics was performed. Their aqueous dispersion radiates bright yellow light under UV lamp (365 nm). The research work includes derivation of their excitation wavelength, observation of influence of dilution on fluorescence and monitoring of emission intensity for about 4 months. The CQDs can effectively recognize the presence of heavy metal ions in aqueous medium at neutral pH via fluorescence quenching.
Carbon quantum dots (CQDs) synthesized at gram scale using low‐cost material. A detailed study of fluorescence characteristics of yellow light emitting CQDs is done. These dots are fluorescence‐stable for about 4 months. These have been utilized for effective recognition of Fe3+, Cu2+, and Cr3+ ions in aqueous medium.
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