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1.
Anal Chem ; 2024 Oct 03.
Article in English | MEDLINE | ID: mdl-39360861

ABSTRACT

The construction of far-red fluorescent molecular rotors (FMRs) is an imperative task for developing nucleic acid stains that have superior compatibility with cellular systems and complex matrices. A typical strategy relies on the methine extension of asymmetric cyanines, which unfortunately fails to produce sensitive rotor character. To break free from this paradigm, we have synthesized far-red hemicyanines using a dimethylamino thieno[3,2-b]thiophene donor. The resultant probes, designated as ATh2Ind and ATh2Btz, possess excitation maxima (λmax) of >600 nm and have been rigorously characterized by NMR, electrochemistry, and computational methods. The dyes possess alternating charge patterns like indodicarbocyanine (Cy5), but with twisted intramolecular charge transfer (TICT) rotational barriers at 60°, akin to the classical FMR thiazole orange (TO1). ATh2Btz also displays cyanine characteristics, enhancing its response upon binding to nucleic acids and allowing for efficient staining of cellular nuclei. When binding to the DNA aptamer for quinine (MN4), ATh2Btz exhibits a Kd of 17 nM, a 660-fold light-up response, brightness (Φfl x εmax) of ∼37,000 M-1cm-1, and λex/λem of 655/677 nm. The resulting far-red DNA-based MN4-ATh2Btz platform has been termed "pomegranate."

2.
Chemosphere ; 365: 143343, 2024 Oct.
Article in English | MEDLINE | ID: mdl-39278330

ABSTRACT

Herein, we report the creation of a novel sensitive electrochemical sensing platform based on a copper and exfoliated graphene oxide (Cu-eGO) nanocomposite using a facile synthesis technique, which simultaneously removes the sodium ions that result from the exfoliation process to generate eGO from graphite. This novel Cu-eGO nanocomposite was characterized via SEM, EDX, Raman and XPS. The Cu-eGO/GCE exhibited much greater activity for the electrochemical oxidation of methimazole than the eGO/GCE or bare GCE. The electrochemical properties and kinetics involved in the oxidation of methimazole at the Cu-eGO were examined using voltammetry and electrochemical impedance spectroscopy (EIS). This Cu-eGO based sensing platform demonstrated high sensitivity at 1.32 µAµM-1cm-2, a low limit of detection at 0.06 µM, robust stability, and strong anti-interference against potential interferents that may exist in biological systems for the detection of methimazole. The developed electrochemical sensor was successfully employed in blood serum samples that mimicked real biological environments, showing its high applicability.


Subject(s)
Copper , Electrochemical Techniques , Graphite , Methimazole , Nanocomposites , Graphite/chemistry , Nanocomposites/chemistry , Copper/chemistry , Copper/analysis , Methimazole/blood , Methimazole/analysis , Methimazole/chemistry , Electrochemical Techniques/methods , Limit of Detection , Oxidation-Reduction , Humans
3.
J Phys Chem Lett ; 15(36): 9208-9215, 2024 Sep 12.
Article in English | MEDLINE | ID: mdl-39225476

ABSTRACT

Atomically dispersed single-atom catalysts have recently attracted broad research interest due to their high atom efficiency and unique catalytic performance. In this study, atomic dispersion of cobalt is achieved using a chemical bath deposition method on a highly stable alkali titanate film (Ti/KTiO). These films were characterized using a variety of techniques, with atomic dispersion confirmed via grazing incidence X-ray absorption spectroscopy and ab initio modeling of single-atom systems. This modeling indicated that the alkali ion incorporated into the film facilitates atomic dispersion. Experimentally, the Ti/KTiO-supported Co(OH)2 catalysts exhibited remarkable electrochemical performance, with an overpotential of 163 mV to achieve a current density of 10 mA cm-2 with a catalyst loading of ∼0.1 mg cm-2 and high stability. These results show the potential of Ti/KTiO/Co(OH)2 catalysts for atomically efficient hydrogen production.

4.
iScience ; 27(9): 110601, 2024 Sep 20.
Article in English | MEDLINE | ID: mdl-39280610

ABSTRACT

Ferroelectric bio-based materials with a high water content (≈90 wt %) were not previously developed. Here, we develop hydrogels containing ≈90 wt % water, amino acids (lysine and arginine) and oleic acid. The NH and CH groups of lysine hydrogen bond water, as shown by attenuated total reflectance-Fourier transform infrared spectroscopy, yielding electrically conductive solutions. Lysine also interacts with oleic acid, yielding hard materials with a lamellar crystal structure, as revealed by synchrotron small angle X-ray scattering. Polarized light microscopy and shear rheology show that aqueous mixtures of amino acids and oleic acid are birefringent gels. These gels have a columnar, hexagonal crystal structure with 54-85 wt % water, and a bi-continuous sponge crystal structure with 89 wt % water. They are piezoelectric, as demonstrated by cyclic voltammetry. Thus, they deform and undergo crystalline phase transitions when exposed to electric fields. The piezoelectric materials developed can find use in medical applications and clean energy harvesting.

5.
ACS Appl Mater Interfaces ; 16(36): 47703-47712, 2024 Sep 11.
Article in English | MEDLINE | ID: mdl-39190043

ABSTRACT

Heteroatom doping has been widely recognized as a key strategy for improving the electrochemical properties of graphene-based materials for hydrogen storage. However, a precise understanding of how heteroatom doping influences catalytic performance, specifically regarding the intricate effects of doping-induced electron redistribution, has been lacking. Here, we report on a comprehensive exploration of the electrochemical performance enhancement in Pd-decorated reduced graphene oxide (rGO) nanocomposites through fluorine (F) or nitrogen (N) doping. Various analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) were employed to thoroughly characterize the synthesized nanocomposites. The findings revealed that either F or N doping effectively addressed clustering issues of Pd nanoparticles formed on the rGO surface, resulting in improved homogeneity of Pd distribution. Electrochemical studies provided crucial insights into hydrogen adsorption-desorption behaviors. The heteroatom doped nanocomposites, Pd/N-rGO and Pd/F-rGO, exhibited superior electrochemical performance, which can be attributed to the increase of the active sites due to the N-/F-doping, respectively. The hydrogen discharge capacities of Pd/N-rGO (80.9 mAh g-1) and Pd/F-rGO (25.0 mAh g-1) nanocomposites were determined to be over 4.0 and 1.2 times higher than that of the Pd/rGO (20.1 mAh g-1), respectively. The distinctive electrochemical performances observed between the two types of heteroatom-containing nanocomposites highlight the subtle structural modifications of Pd nanoparticles as the key factor influencing performance. This research contributes essential knowledge to the evolving field of hydrogen storage materials, emphasizing the promising potential of heteroatom-doped Pd-decorated rGO nanocomposites for advancing clean and sustainable energy solutions.

6.
Langmuir ; 40(31): 16249-16257, 2024 Aug 06.
Article in English | MEDLINE | ID: mdl-39066730

ABSTRACT

Nicotinamide adenine dinucleotide-dependent formate dehydrogenase from Candida boidinii was immobilized in a 1,2-dimyristoyl-sn-glycero-3-phosphocholine/cholesterol floating lipid bilayer on the gold surface as a biocatalyst for electrochemical CO2 reduction. We report that, in contrast to common belief, the enzyme can catalyze the electrochemical reduction of CO2 to formate without the cofactor protonated nicotinamide adenine dinucleotide. The electrochemical data indicate that the enzyme-catalyzed reduction of CO2 is diffusion-controlled and is a reversible reaction. The orientation and conformation of the enzyme were investigated by surface-enhanced infrared reflection absorption spectroscopy. The α-helix of the enzyme adopts an orientation nearly parallel to the surface, bringing its active center close to the gold surface. This orientation allows direct electron transfer between CO2 and the gold electrode. The results in this paper provide a new method for the development of enzymatic electrocatalysts for CO2 reduction.


Subject(s)
Carbon Dioxide , Enzymes, Immobilized , Formate Dehydrogenases , Oxidation-Reduction , Formate Dehydrogenases/chemistry , Formate Dehydrogenases/metabolism , Carbon Dioxide/chemistry , Carbon Dioxide/metabolism , Enzymes, Immobilized/chemistry , Enzymes, Immobilized/metabolism , Biocatalysis , Candida/enzymology , Electrochemical Techniques , Electrodes , Gold/chemistry , Catalysis , Lipid Bilayers/chemistry , Lipid Bilayers/metabolism , Saccharomycetales
7.
Nanoscale ; 16(27): 12967-12981, 2024 Jul 11.
Article in English | MEDLINE | ID: mdl-38899409

ABSTRACT

The search for an efficient and stable catalyst for the electrochemical reduction of CO2 to value-added chemicals is especially critical for lowering the atmospheric CO2 concentration. In this study, self-supported cobalt/copper nanostructured catalysts were designed, where the influences of the elemental composition and acid-etching on their efficiency towards the CO2 reduction reaction were studied. The developed Co/Cu catalysts showed superb catalytic activity with a low onset potential at -0.2 V vs. RHE. Gas and liquid product analysis revealed that formate and CO were the main products. It was observed that lower reductive potentials were favourable for formate production, while higher reductive potentials were more favourable for CO formation. In situ electrochemical FTIR studies were further conducted to gain insight into the CO2 reduction mechanism. The novel synthetic procedure reported in this study leads to promising electrocatalysts with high efficiencies for the conversion of CO2 into valuable products.

8.
Analyst ; 149(14): 3773-3782, 2024 Jul 08.
Article in English | MEDLINE | ID: mdl-38845549

ABSTRACT

Cardiovascular disease is one of the leading causes of premature death worldwide, and the determination of C-reactive protein (CRP) from human serum is of vital importance for the diagnosis of the disease. For this study, we have developed an electrochemical immunosensor based on onion-like carbon@polyacrylonitrile (OLC-PAN) for the detection of CRP antigens. This was accomplished by immobilizing CRP antibodies on a modified glassy carbon electrode (GCE). Several electrochemical techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) were employed to evaluate the electrochemical detection of the CRP antigen. This ultrasensitive method for CRP antigen detection exhibited a very good logarithmic plot from -4.52 to -12.05 g mL-1 and a limit of detection (LOD) of 0.9 fg mL-1. The high selectivity, sensitivity, and stability of the developed electrochemical immunosensor would facilitate miniaturization for point-of-care applications and the efficient diagnosis of cardiovascular diseases.


Subject(s)
Antibodies, Immobilized , Biosensing Techniques , C-Reactive Protein , Electrochemical Techniques , Electrodes , Limit of Detection , C-Reactive Protein/analysis , C-Reactive Protein/immunology , Humans , Electrochemical Techniques/methods , Biosensing Techniques/methods , Immunoassay/methods , Antibodies, Immobilized/immunology , Antibodies, Immobilized/chemistry , Acrylic Resins/chemistry , Carbon/chemistry , Antigens/immunology , Antigens/chemistry
9.
ChemSusChem ; : e202400437, 2024 May 07.
Article in English | MEDLINE | ID: mdl-38712937

ABSTRACT

Carbon capture and utilization (CCU) are technologies sought to reduce the level of CO2 in the atmosphere. Industrial carbon capture is associated with energetic penalty, thus there is an opportunity to research alternatives. In this work, spectroelectrochemistry was used to analyze the electrochemical CO2 reduction (eCO2R) in CO2 saturated monoethanolamine (MEA)-based capture solutions, in a novel CCU process. The in situ Fourier transform infrared (FTIR) spectroscopy experiments show that at the Bi catalyst, the active species involved in the eCO2R is the dissolved CO2 in solution, and not carbamate. In addition, the products of eCO2R were evaluated under flow, using commercial Bi2O3 NP as catalyst. Formate and acetate were detected, with normalized FE for acetate up to 14.5 %, a remarkable result, considering the catalyst used. Acetate is formed either in the presence of cetrimonium bromide (CTAB) as surfactant or at higher current density (>-100 mA cm-2) and the results enabled the proposition of a pathway for its production. This work sheds light on the complex reaction environment of a capture medium electrolyte and is thus relevant for an improved understanding of the conversion of CO2 into value-added products and to evaluate the feasibility of a combined CCU approach.

10.
ACS Appl Mater Interfaces ; 16(15): 18300-18310, 2024 Apr 17.
Article in English | MEDLINE | ID: mdl-38574271

ABSTRACT

To tackle the proliferation of pathogenic microorganisms without relying on antibiotics, innovative materials boasting antimicrobial properties have been engineered. This study focuses on the development of graphene oxide/silver (GO/Ag) nanocomposites, derived from partially reduced graphene oxide adorned with silver nanoparticles. Various nanocomposites with different amounts of silver (GO/Ag-1, GO/Ag-2, GO/Ag-3, and GO/Ag-4) were synthesized, and their antibacterial efficacy was systematically studied. The silver nanoparticles were uniformly deposited on the partially reduced graphene oxide surface, exhibiting spherical morphologies with an average size of 25 nm. The nanocomposites displayed potent antibacterial properties against both gram-positive bacteria (S. aureus and B. subtilis) and gram-negative bacteria (E. coli and S. enterica) as confirmed by minimum inhibition concentration (MIC) studies and time-dependent experiments. The optimal MIC for Gram-positive bacteria was 62.5 µg/mL and for Gram-negative bacteria was 125 µg/mL for the GO/Ag nanocomposites. Bacterial cells that encountered the nanocomposite films exhibited significantly greater inhibitory effects compared to those exposed to conventional antibacterial materials. Furthermore, the cytotoxicity of these nanocomposites was assessed using human epithelial cells (HEC), revealing that GO/Ag-1 and GO/Ag-2 exhibited lower toxicity levels toward HEC and remained compatible even at higher dilution rates. This study underscores the potential of GO/Ag-based nanocomposites as versatile materials for antibacterial applications, particularly as biocompatible wound dressings, offering promising prospects for wound healing and infection control.


Subject(s)
Graphite , Metal Nanoparticles , Nanocomposites , Humans , Silver/pharmacology , Staphylococcus aureus , Escherichia coli , Oxides/pharmacology , Anti-Bacterial Agents/pharmacology , Graphite/pharmacology
11.
ACS Appl Mater Interfaces ; 16(17): 21895-21904, 2024 May 01.
Article in English | MEDLINE | ID: mdl-38636081

ABSTRACT

There is a growing interest in creating cost-effective catalysts for efficient electrochemical CO2 reduction to address pressing environmental issues and produce valuable products. A bimetallic ZnBi catalyst that enhances catalytic activity and stability toward the electrochemical reduction of CO2 is designed. It is based on bismuth nanodendrites grown using a facile, scalable, and low-cost method. The results have shown that the incorporation of bismuth can decrease the charge transfer resistance and facilitate CO2 reduction toward the formation of CO and formate. It was revealed that the ZnBi catalyst exhibited higher catalytic activity compared with that of the pure Zn catalyst for CO2 reduction, with a lower onset potential [-0.75 V vs a reversible hydrogen electrode (RHE) compared with -0.85 V vs RHE for Zn]. In situ electrochemical attenuated total internal reflection Fourier transform infrared spectroscopy was employed to study the reaction mechanism, showing the formation of CO and formate through the adsorbed *COO- intermediates. This study has demonstrated a new approach for the feasible synthesis of high-performance catalysts for large-scale electrochemical CO2 reduction.

12.
Langmuir ; 40(15): 8248-8259, 2024 04 16.
Article in English | MEDLINE | ID: mdl-38578277

ABSTRACT

A model bilayer of the outer membrane (OM) of Gram-negative bacteria, composed of lipid A and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE), was assembled on the ß-Tg modified gold (111) single crystal surface using a combination of Langmuir-Blodgett and Langmuir-Schaefer transfer. Electrochemical and spectroscopic methods were employed to study the properties of the model bilayer and its interaction with polymyxin. The model bilayer is stable on the gold surface in the transmembrane potential region between 0.0 and -0.7 V. The presence of Mg2+ coordinates with the phosphate and carboxylate groups in the leaflet of lipid A and stabilizes the structure of the model bilayer. Polymyxin causes the model bilayer leakage and damage in the transmembrane potential region between 0.2 and -0.4 V. At transmembrane potentials lower than -0.5 V, polymyxin does not affect the membrane integrity. Polymyxin binds to the phosphate and carboxylate groups in lipid A molecules and causes the increase of the tilt angle of acyl chains and the decrease of the tilt of the C═O bond. The results in this paper indicate that the antimicrobial activity of polymyxin depends on the transmembrane potential at the model bilayer and provides useful information for the development of new antibiotics.


Subject(s)
Anti-Bacterial Agents , Lipid Bilayers , Anti-Bacterial Agents/pharmacology , Lipid Bilayers/chemistry , Lipid A , Polymyxins/pharmacology , Gram-Negative Bacteria , Gold/chemistry , Phosphates
13.
Nanomaterials (Basel) ; 13(18)2023 Sep 19.
Article in English | MEDLINE | ID: mdl-37764617

ABSTRACT

Hydrogen is a promising green fuel carrier that can replace fossil fuels; however, its storage is still a challenge. Carbon-based materials with metal catalysts have recently been the focus of research for solid-state hydrogen storage due to their efficacy and low cost. Here, we report on the exfoliation of expanded graphite (EG) through high shear mixing and probe tip sonication methods to form graphene-based nanomaterial ShEG and sEG, respectively. The exfoliation processes were optimized based on electrochemical capacitance measurements. The exfoliated EG was further functionalized with palladium nanoparticles (Pd-NP) for solid-state hydrogen storage. The prepared graphene-based nanomaterials (ShEG and sEG) and the nanocomposites (Pd-ShEG and Pd-sEG) were characterized with various traditional techniques (e.g., SEM, TEM, EDX, XPS, Raman, XRD) and the advanced high-resolution pair distribution function (HRPDF) analysis. Electrochemical hydrogen uptake and release (QH) were measured, showing that the sEG decorated with Pd-NP (Pd-sEG, 31.05 mC cm-2) and ShEG with Pd-NP (Pd-ShEG, 24.54 mC cm-2) had a notable improvement over Pd-NP (9.87 mC cm-2) and the composite of Pd-EG (14.7 mC cm-2). QH showed a strong linear relationship with an effective surface area to volume ratio, indicating nanoparticle size as a determining factor for hydrogen uptake and release. This work is a promising step toward the design of the high-performance solid-state hydrogen storage devices through mechanical exfoliation of the substrate EG to control nanoparticle size and dispersion.

14.
Chem Sci ; 14(36): 9678-9688, 2023 Sep 20.
Article in English | MEDLINE | ID: mdl-37736653

ABSTRACT

Single-atom catalysts have been extensively utilized for electrocatalysis, in which electronic metal-support interactions are typically employed to stabilize single atoms. However, this neglects the metal-metal interactions of adjacent atoms, which are essential for the fine-tuning of selective sites. Herein, the high-loading of Ir single atoms (Ir SAs) (8.9 wt%) were adjacently accommodated into oxygen vacancy-rich Co3O4 nanosheets (Ir SAs/Co3O4). Electronic perturbations for both Ir single atoms and Co3O4 supports were observed under electronic metal-support and metal-metal interactions, thus generating Ir-O-Co/Ir units. Electrons were transferred from Co and Ir to O atoms, inducing the depletion of 3d/5d states in Co/Ir and the occupation of 2p states in O atoms to stabilize the Ir SAs. Moreover, the O atoms of Ir-O-Ir functioned as the main active sites for the electrocatalysis of As(iii), which reduced the energy barrier for the rate-determining step. This was due to the stronger electronic affinities for intermediates from reduction of As(iii), which were completely distinct from other coordinated O atoms of Co3O4 or IrO2. Consequently, the resultant Ir SAs/Co3O4 exhibited far more robust electrocatalytic activities than IrO2/Co3O4 and Co3O4 in the electrocatalysis of As(iii). Moreover, there was a strong orbital coupling effect between the coordinated O atoms of Ir SAs and the -OH of H3AsO3, thus exhibiting superior selectivity for As(iii) in contrast to other common heavy metal cations. This work offers useful insights into the rational design of intriguing SACs with high selectivity and stability for the electrocatalysis and electrochemical analysis of pollutants on an electronic level.

15.
Langmuir ; 39(33): 11750-11759, 2023 Aug 22.
Article in English | MEDLINE | ID: mdl-37556464

ABSTRACT

Cobalt-ceria binary oxide nanojunctions were prepared by a sol-gel method with various chelating agents. The formed interfaces among CeO2 and Co3O4 can promote the generation of nucleophilic •O2- from O2 and then tune the catalytic oxidizability of the as-prepared CoCe nanojunctions. Given the results of HMF oxidations, malic acid as a complexing agent during the preparation process of the cobalt-ceria binary oxide nanojunctions can lead to a good catalytic performance on HMF oxidations to FDCA, and a remarkable FDCA selectivity of 92.3% and almost 100% HMF conversion were obtained at 110 °C under O2 and alkali conditions. By comparing the catalytic performance of the nanojunctions and physical mixing of cobalt-ceria binary oxide on oxidations of HMF, 5-hydroxymethyl-2-furancarboxylic acid (HFCA), and 5-formyl-2-furancarboxylic acid (FFCA), the interfaces intrinsically enhanced the FDCA yield dominantly via boosting the HMF oxidation to HFCA with •O2- during the stepwise oxidation of HMF to FDCA. It can be enlightening that the introduction of the active sites for transforming O2 to •O2- to promote the transformation of HMF into HFCA is the key to boosting the selective aerobic oxidation of HMF to FDCA.

16.
J Phys Chem Lett ; 14(19): 4600-4606, 2023 May 18.
Article in English | MEDLINE | ID: mdl-37166101

ABSTRACT

A deep understanding of the properties of semiconductor films at the micro-/nanoscale level is fundamental toward designing effective photoelectrocatalysts. Here, we integrated spatially resolved optical spectroscopy (SR-OS) with scanning photoelectrochemical microscopy (SPECM) to collect UV/vis spectra and quantify photocurrents of localized sites on a nanostructured BiVO4 thin film. Direct measurement of absorbance allowed for the determination of band gap energy at each location. Absorbance and photocurrent maps were obtained and used to investigate heterogeneities on the films. Scanning electrochemical cell microscopy (SECCM) was also coupled with SR-OS to acquire quantitative photoelectrochemical data at the FTO/BiVO4 film interface, revealing higher photocurrents at the boundary regions. As a droplet-based technique, SECCM was employed to estimate the wetted area by measuring the maximum height of droplet stretch at each point, allowing for the calculation of photocurrent density. This novel approach provides an advantageous mean to correlate localized photocatalytic activities and band gap energies.

17.
Nanomaterials (Basel) ; 13(4)2023 Feb 20.
Article in English | MEDLINE | ID: mdl-36839146

ABSTRACT

Cu-based nanomaterials have been widely considered to be promising electrocatalysts for the direct conversion of CO2 to high-value hydrocarbons. However, poor selectivity and slow kinetics have hindered the use of Cu-based catalysts for large-scale industrial applications. In this work, we report on a tunable Cu-based synthesis strategy using a dynamic hydrogen bubble template (DHBT) coupled with a sputtered Ag thin film for the electrochemical reduction of CO2 to ethanol. Remarkably, the introduction of Ag into the base of the three-dimensional (3D) Cu nanostructure induced changes in the CO2 reduction reaction (CO2RR) pathway, which resulted in the generation of ethanol with high Faradaic Efficiency (FE). This observation was further investigated through Tafel and electrochemical impedance spectroscopic analyses. The rational design of the electrocatalyst was shown to promote the spillover of formed CO intermediates from the Ag sites to the 3D porous Cu nanostructure for further reduction to C2 products. Finally, challenges toward the development of multi-metallic electrocatalysts for the direct catalysis of CO2 to hydrocarbons were elucidated, and future perspectives were highlighted.

18.
Chemosphere ; 318: 137985, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36716933

ABSTRACT

The presence of herbicides like Atrazine (ATZ) in groundwater from non-target runoff of the agriculture industry becomes a big concern due to its potential negative impacts on the environment and human health. The use of advanced oxidative processes (AOP) to remove harmful contaminants has been shown to be effective for wastewater treatment. Herein, we report on an advanced photoelectrochemical (PEC) approach based on electrochemically modified nanoporous TiO2 electrode for efficient degradation of ATZ. The electrochemical treated TiO2 electrodes were shown to have a six-fold increase in the photo-current density over the untreated ones. This increase in PEC activity was attributed to the increase in Ti3+ sites after the electrochemical modification, which was corroborated by low-temperature electron paramagnetic resonance (EPR) studies. The removal of ATZ by the PEC process resulted in a rate constant of 1.91 × 10-3 s-1, compared to 3.12 × 10-4 s-1 obtained by a strictly photocatalytic process. Liquid-Chromatography Mass-Spectrometric measurements showed the modified TiO2 electrodes highly effective at removing ATZ, with 96.1% removed after 10 h. Monitoring of the common degradation products desethyl atrazine (DEA), desisopropyl atrazine (DIA) and desethyl desisopropyl atrazine (DDA) revealed very low concentrations throughout the degradation process, indicating that further degradation was achieved. Quantum mechanical-based test for overall free radical scavenging activity (QM-ORSA) computational studies were performed and a mechanism for the N-dealkylation processes of ATZ has been proposed.


Subject(s)
Atrazine , Herbicides , Nanopores , Water Pollutants, Chemical , Humans , Atrazine/chemistry , Water Pollutants, Chemical/analysis , Herbicides/chemistry , Titanium/chemistry
19.
Micromachines (Basel) ; 13(12)2022 Dec 04.
Article in English | MEDLINE | ID: mdl-36557442

ABSTRACT

Monitoring pH changes at the micro/nano scale is essential to gain a fundamental understanding of surface processes. Detection of local pH changes at the electrode/electrolyte interface can be achieved through the use of micro-/nano-sized pH sensors. When combined with scanning electrochemical microscopy (SECM), these sensors can provide measurements with high spatial resolution. This article reviews the state-of-the-art design and fabrication of micro-/nano-sized pH sensors, as well as their applications based on SECM. Considerations for selecting sensing probes for use in biological studies, corrosion science, in energy applications, and for environmental research are examined. Different types of pH sensitive probes are summarized and compared. Finally, future trends and emerging applications of micro-/nano-sized pH sensors are discussed.

20.
Molecules ; 27(24)2022 Dec 07.
Article in English | MEDLINE | ID: mdl-36557776

ABSTRACT

Here, we report on a new automated electrochemical process for the production of graphene oxide (GO) from graphite though electrochemical exfoliation. The effects of the electrolyte and applied voltage were investigated and optimized. The morphology, structure and composition of the electrochemically exfoliated GO (EGO) were probed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), FTIR spectroscopy and Raman spectroscopy. Important metrics such as the oxygen content (25.3 at.%), defect density (ID/IG = 0.85) and number of layers of the formed EGO were determined. The EGO was also compared with the GO prepared using the traditional chemical method, demonstrating the effectiveness of the automated electrochemical process. The electrochemical properties of the EGO, CGO and other carbon-based materials were further investigated and compared. The automated electrochemical exfoliation of natural graphite powder demonstrated in the present study does not require any binders; it is facile, cost-effective and easy to scale up for a large-scale production of graphene-based nanomaterials for various applications.

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