Publications by authors named "Jayaraman Theerthagiri"

24 Publications

  • Page 1 of 1

Method development and mechanistic study on direct pulsed laser irradiation process for highly effective dechlorination of persistent organic pollutants.

Environ Pollut 2021 Sep 14;291:118158. Epub 2021 Sep 14.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry, Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea. Electronic address:

Chlorine-based compounds are typical persistent organic pollutants (POPs) that are widely generated in industrial production. This paper reports an effective and rapid pulsed laser irradiation technique for the dechlorination of hexachlorobenzene (HCB), a model pollutant, without additional catalysts or supports. The effects of the laser parameters, including the laser wavelength and power, on the dechlorination efficiency, were also investigated. The optimized results showed that a lower laser wavelength of 266 nm with 10 mJ/pulse power exhibited the highest dechlorination efficiency with 95% within 15 min. In addition, the laser beam effect was examined by designing the direct-pulsed laser single and multipath irradiation system. The results showed that improving the laser beam profile resulted in more than 95% dechlorination efficiency within 5 min. Thus, the dechlorination reaction proceeded much faster as the surface area that the laser beam came in contact with increased due to the multipath system than the single pathway. Gas chromatography identified benzene as the final product of HCB with pentachlorobenzene (PCB), tetrachlorobenzene (TeCB), trichlorobenzene (TCB), dichlorobenzene (DCB), and chlorobenzene (CB) as intermediate products. The mechanism of HCB dechlorination was explained by a comparison of theoretical calculations with the experimental results. The present study reports an advanced technique for the complete dechlorination of chlorobenzenes, which holds great application potential in environmental remediation.
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http://dx.doi.org/10.1016/j.envpol.2021.118158DOI Listing
September 2021

Silane-treated BaTiO ceramic powders for multilayer ceramic capacitor with enhanced dielectric properties.

Chemosphere 2021 Jul 29;286(Pt 2):131734. Epub 2021 Jul 29.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea. Electronic address:

Silane/ceramic combination provides the composites with several advantages from the advancements of new ceramic composite materials with good thermal conductivity, high mechanical and dielectric properties have wide significant applications in electrical and electronic industries. In this study, to enhance the dispersibility of dielectric barium titanate (BaTiO) ceramic powder and additives for the fabrication of multilayer ceramic capacitors (MLCCs), surface treatment of the precursor of ceramic powder was performed using silane coupling agents. Dielectric ceramic sheets fabricated from ceramic powders that had been surface-treated with different amounts of N-[3-(trimethoxysilyl)propyl]aniline (TMSPA) which increased the surface gloss. In particular, the dielectric properties of the multilayer ceramic sheet fabricated by stacking sheets from the TMSPA-treated ceramic powder sintering at 1200 °C, it was confirmed that the dielectric constant increased from 881 to 2382 and the dielectric loss dropped from 1.96 to 1.34% with utilization of the TMSPA treatment. The physical and dielectric properties of the TMSPA-treated multilayer ceramic sheet were also determined by Fourier-transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, glossmetry, and electrochemical impedance analysis. The results revealed that the TMSPA-modified BaTiO surfaces considerably increased the dielectric property of the fabricated nanocomposite.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131734DOI Listing
July 2021

Fabrication strategies and surface tuning of hierarchical gold nanostructures for electrochemical detection and removal of toxic pollutants.

J Hazard Mater 2021 Jul 14;420:126648. Epub 2021 Jul 14.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju 52828, South Korea. Electronic address:

The intensive research on the synthesis and characterization of gold (Au) nanostructures has been extensively documented over the last decades. These investigations allow the researchers to understand the relationships between the intrinsic properties of Au nanostructures such as particle size, shape, morphology, and composition to synthesize the Au nano/hybrid nanostructures with novel physicochemical properties. By tuning the properties above, these nanostructures are extensively employed to detect and remove trace amounts of toxic pollutants from the environment. This review attempts to document the achievements and current progress in Au-based nanostructures, general synthetic and fabrication strategies and their utilization in electrochemical sensing and environmental remediation applications. Additionally, the applications of Au nanostructures (e.g., as adsorbents, sensing platforms, catalysts, and electrodes) and advancements in the field of electrochemical sensing of different target analytes (e.g., proteins, nucleic acids, heavy metals, small molecules, and antigens) are summarized. The literature survey concludes the existing methods for the detection of toxic contaminants at various concentration levels. Finally, the existing challenges and future research directions on electrochemical sensing and degradation of toxic contaminants using Au nanostructures are defined.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126648DOI Listing
July 2021

2D advanced materials and technologies for industrial wastewater treatment.

Chemosphere 2021 Jun 29;284:131394. Epub 2021 Jun 29.

Institute of Chemistry, Universidade Federal de Mato Grosso Do Sul, Senador Filinto Muller Avenue, 1555, Campo Grande, Mato Grosso do Sul, 79074-460, Brazil. Electronic address:

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http://dx.doi.org/10.1016/j.chemosphere.2021.131394DOI Listing
June 2021

Lignin-mediated green synthesis of functionalized gold nanoparticles via pulsed laser technique for selective colorimetric detection of lead ions in aqueous media.

J Hazard Mater 2021 Jul 6;420:126585. Epub 2021 Jul 6.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR) and Research Institute of Natural Sciences, Gyeongsang National University, Jinju 52828, South Korea. Electronic address:

A versatile green synthesis technique of pulsed laser irradiation and the sonochemical process was used for the production of functionalized gold nanoparticles (Au NPs) in the presence of lignin matrixes. In this study, the futuristic advantages of the lignin biopolymer were explored for the preparation of zero-valent Au NPs in the absence of any other reducing agents. The resulting lignin functionalized Au NPs (L-Au NPs) were characterized via high-resolution transmission electron microscopy, X-ray diffraction, UV-vis spectroscopy, and Fourier-transform infrared spectroscopy. The optimum lignin concentration can generate uniformly dispersed crystalline L-Au NPs. The optimized L-Au (1-5) NPs permit the selective colorimetric detection of heavy metal ions; thus, the L-Au (1-5) NPs demonstrated a highly selective colorimetric sensing tendency toward Pb ions within a short time interval among the various metal ions (Pb, Fe, Cu, Cr, Co, Ag, Ca, Cd, Ba, and Hg). The prominent color change of L-Au NPs from red wine to purple indicates the detection of Pb ions. This robust characteristic nature of L-Au (1-5) NPs can also detect very low concentrations of 1.8 μM in the linear range of 0.1-1 mM. Hence, the outcome of this study coincides with existing studies and indicates that L-Au (1-5) NPs can also be used as effective sensors for the rapid and selective detection of Pb ions via the colorimetric analysis using the real environmental samples.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126585DOI Listing
July 2021

Facile one-pot synthesis of CuCN by pulsed laser ablation in nitrile solvents and mechanistic studies using quantum chemical calculations.

Sci Rep 2021 Jul 13;11(1):14389. Epub 2021 Jul 13.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea.

Binding energies of different nitrile solvents and their utilization for CuCN formation were investigated through quantum chemical calculations. A pulsed laser ablation in liquid (PLAL) method for CuCN synthesis was developed herein. Initially, the interaction between the pulsed laser and the Cu-target generated Cu-ions and electrons at the point of contact. The laser beam also exhibited sufficient energy to dissociate the bonds of the respective solvents. In the case of acetonitrile, the oxidized Cu-ions bonded with CN to produce CuCN with a cube-like surface structure. Other nitrile solvents generated spherically-shaped [email protected] carbon ([email protected]) nanoparticles. Thus, the production of CuCN was favorable only in acetonitrile due to the availability of the cyano group immediately after the fragmentation of acetonitrile (CH and CN) under PLAL. Conversely, propionitrile and butyronitrile released large amounts of hydrocarbons, which deposited on Cu NPs surface to form GC layers. Following the encapsulation of Cu NPs with carbon shells, further interaction with the cyano group was not possible. Subsequently, theoretical study on the binding energies of nitrile solvents was confirmed by highly correlated basic sets of B3LYP and MP2 which results were consistent with the experimental outcomes. The findings obtained herein could be utilized for the development of novel metal-polymer materials.
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http://dx.doi.org/10.1038/s41598-021-93768-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8277773PMC
July 2021

In-situ thermal phase transition and structural investigation of ferroelectric tetragonal barium titanate nanopowders with pseudo-cubic phase.

Chemosphere 2021 Nov 14;283:131218. Epub 2021 Jun 14.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea. Electronic address:

Optimization and miniaturization of existing electronic devices require the development of advanced nanostructured materials with high phase and structural purity. Over the past decade, barium titanate (BaTiO) has attracted considerable attention due to its outstanding ferroelectric and dielectric properties. The present study involved the investigation of the phase transition and structural stability of tetragonal BaTiO nanopowders with pseudo-cubic phase using an in-situ high resolution and high temperature X-ray diffraction method. Under ambient conditions, the coexistence the tetragonal and cubic phases with weight fractions of 75.7% and 24.3%, respectively, was determined in BaTiO. In the temperature range of 25 °C-300 °C, phase boundaries of BaTiO (180 nm in size) exhibiting several phases were detected. The phase transformation behavior, relative crystal phase content, lattice parameters, crystallite size, and tetragonality of the BaTiO nanopowders were established by the Rietveld refinement method at the onset temperature from 25 °C to 300 °C. Up to 150 °C, the nanopowders exhibited a complete transition of the cubic phase. Additionally, a complete tetragonal to cubic transformation was accomplished by a decrease of tetragonality at 125 °C and an increase in the crystallite size at 300 °C.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131218DOI Listing
November 2021

Rapid and highly selective electrochemical sensor based on ZnS/Au-decorated f-multi-walled carbon nanotube nanocomposites produced via pulsed laser technique for detection of toxic nitro compounds.

J Hazard Mater 2021 09 1;418:126269. Epub 2021 Jun 1.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry (BK21 FOUR), Research Institute of Natural Sciences, Gyeongsang National University, Jinju 52828, Republic of Korea. Electronic address:

Novel ZnS/Au/f-multi-walled carbon nanotube (MWCNT) nanostructures were produced via a pulsed laser-assisted technique followed by a wet chemical process. ZnS nanospheres were synthesized via pulsed laser ablation of a Zn target in DMSO, which was used as a solvent and sulfur source. Notably, no additional sulfur sources, surfactants, or reducing agents were used during the synthesis. The structure and morphology of the prepared materials were characterized by X-ray diffraction, micro-Raman spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The fabricated electrochemical sensor based on ZnS/Au/f-MWCNT nanocomposites exhibited rapid and highly selective detection of a toxic pollutant, namely 4-nitrophenol (4-NP). Linear sweep voltammetry analysis revealed that the optimized ZnS/Au10/f-MWCNT3 nanocomposite displayed a wide linear dynamic response (10-150 μM) with high sensitivity (0.8084μAμMcm) and low limit of detection (30 nM). The excellent 4-NP sensing performance of the modified electrode was attributed to the availability of numerous active sites (electrochemical surface area=0.00369μFcm) and an enhanced electron transfer rate. Interference and stability studies were also conducted. A 100-fold excess of competing ions (Na, K, Mg, Cl, NO, 4-AP, AA, and 2-NP) did not interfere with the selective detection of 4-NP. The newly fabricated ZnS/Au10/f-MWCNT3 nanocomposite could be an effective sensor for the selective and sensitive detection of toxic organic nitro compounds.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126269DOI Listing
September 2021

Editorial to surface tailored innovative materials and technologies for wastewater treatment.

Environ Pollut 2021 Sep 21;284:117436. Epub 2021 May 21.

Department of Chemical Engineering, Khalifa University of Science and Technology (KUST), Sas Al Nakhl Campus, Abu Dhabi, P.O 2533, United Arab Emirates. Electronic address:

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http://dx.doi.org/10.1016/j.envpol.2021.117436DOI Listing
September 2021

Synthesis of TiO/RGO with plasmonic Ag nanoparticles for highly efficient photoelectrocatalytic reduction of CO to methanol toward the removal of an organic pollutant from the atmosphere.

Environ Pollut 2021 Jul 23;281:116990. Epub 2021 Mar 23.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

The synergistic photoelectrochemical (PEC) technology is a robust process for the conversion of CO into fuels. However, designing a highly efficient UV-visible driven photoelectrocatalyst is still challenging. Herein, a plasmonic Ag NPs modified TiO/RGO photoelectrocatalyst (Ag-TiO/RGO) has been designed for the PEC CO reduction into selective production of CHOH. HR-TEM analysis revealed that Ag and TiO NPs with average sizes of 4 and 7 nm, respectively, were densely grown on the few-micron-sized 2D RGO nanosheets. The physicochemical analysis was used to determine the optical and textural properties of the Ag-TiO/RGO nanohybrids. Under VU-Vis light illumination, Ag-TiO/RGO photocathode possessed a current density of 23.5 mA cm and a lower electrode resistance value of 125 Ω in CO-saturated 1.0 M KOH-aqueous electrolyte solution. Catalytic studies showed that the Ag-TiO/RGO photocathode possessed a remarkable PEC CO reduction activity and selective production of CHOH with a yield of 85 μmol L cm, the quantum efficiency of 20% and Faradic efficiency of 60.5% at onset potential of -0.7 V. A plausible PEC CO reduction mechanism over Ag-TiO/RGO photocathode is schematically demonstrated. The present work gives a new avenue to develop high-performance and stable photoelectrocatalyst for PEC CO reduction towards sustainable liquid fuels production.
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http://dx.doi.org/10.1016/j.envpol.2021.116990DOI Listing
July 2021

Solvent-mediated synthesis of BiOI with a tunable surface structure for effective visible light active photocatalytic removal of Cr(VI) from wastewater.

Environ Res 2021 06 26;197:111080. Epub 2021 Mar 26.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry, Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, Republic of Korea. Electronic address:

The present study investigated the effect of various solvents on the tunable surface morphology and photocatalytic activity (PCA) of bismuth oxyiodide (BiOI), which could be used for the reduction of Cr(VI) under visible light irradiation (VLI). BiOI samples exhibiting different morphologies, i.e., two-dimensional square-like nanosheet and three-dimensional hierarchical flower-like morphology, were synthesized by a hydro/solvothermal process using different solvents, namely HO, MeOH, EtOH, and ethylene glycol (EG). The crystal structure, surface morphology, surface area, light-absorption capability, and recombination rate of the photogenerated charge carriers were examined by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller analysis, UV-vis diffuse reflectance spectroscopy, photoluminescence, and transient photocurrent analyses, respectively. The BiOI sample fabricated in EG showed excellent photocatalytic efficiency (~99%) for the reduction of Cr(VI) after 90 min under VLI. The enhanced PCA demonstrated that the high surface area and well-structured surface characteristics of flower-like 3D BiOI microspheres played important roles in the photoreduction process. Moreover, a plausible mechanism for the reduction of Cr(VI) over the EG-BiOI photocatalyst was proposed. The results of the PCA evaluation and recycle test revealed that 3D EG-BiOI microspheres could serve as promising materials for the efficient removal of Cr(VI) from wastewater. Additionally, EG-BiOI could be utilized in other environmental remediation processes.
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http://dx.doi.org/10.1016/j.envres.2021.111080DOI Listing
June 2021

Application of advanced materials in sonophotocatalytic processes for the remediation of environmental pollutants.

J Hazard Mater 2021 06 26;412:125245. Epub 2021 Jan 26.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry, Research Institute of Natural Sciences, Gyeongsang National University, Jinju 52828, Republic of Korea. Electronic address:

Significant advances in various industrial processes have resulted in the discharge of toxic pollutants into the environment. Consequently, it is essential to develop efficient wastewater treatment processes to reduce water contamination and increase recycling/reuse. Photocatalytic degradation is considered as an efficient method for the degradation of toxic pollutants in industrial wastewater. However, the use of photocatalytic approaches is associated with numerous limitations, such as lengthy procedures and the necessity for large amounts of catalysts. Hence, it has been proposed that photocatalysis could be combined with other techniques, including sonolysis, electrochemical, photothermal, microwave, ultrafiltration, and biological reactor. The integration of photocatalysis with sonolysis could be remarkably beneficial for environmental remediation. The combination of these processes has the advantages of using uniformly dispersed catalysts, regeneration of the catalyst surface, improved mass transfer, enhanced surface area due to smaller catalyst particles, and production of more active radicals for the degradation of organic pollutants. In this review, an overview on employing sonophotocatalysis for the removal of toxic organic contaminants from aqueous environments is provided. Additionally, the limitations of photocatalysis alone and the fundamental sonophotocatalytic mechanistic pathways are discussed. The importance of utilizing advanced two-dimensional (2D) semiconductor materials in sonophotocatalysis and the common synthetic approaches for the preparation of 2D materials are also highlighted. Lastly, the review provides comprehensive insights into different materials based on metal oxides, chalcogenides, graphene, and metal organic frameworks (MOFs), which are involved in sonophotocatalytic processes employed for the remediation of environmental pollutants.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125245DOI Listing
June 2021

Anthracene-based fluorescent probe: Synthesis, characterization, aggregation-induced emission, mechanochromism, and sensing of nitroaromatics in aqueous media.

Environ Res 2021 03 13;194:110741. Epub 2021 Jan 13.

Core-Facility Center for Photochemistry & Nanomaterials, Department of Chemistry, Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, South Korea. Electronic address:

The sensitive and selective detection of nitroexplosive molecules thorough a simple methodology has received a significant field of research affecting global security and public safety. In the present study, the synthesis of anthracene-based chalcone (S1) was conducted using a simple condensation method. S1 was found to exhibit unique properties, such as aggregation-induced emission in solution and mechanochromic behavior in solid state. A fluorescent aggregate was applied to sense electron-deficient picric acid (PA) and 2,4-dinitrophenol (2,4-DNP) in an aqueous solution. Notably, the developed test strip-based sensor (S1) could be used to effectively detect PA and 2,4-DNP, which were visualized by the naked eye. Photophysical analysis revealed the occurrence of an electron transfer from electron-rich S1 to the electron-deficient nitro compounds, which was confirmed using density functional theory and H-nuclear magnetic resonance studies. In addition, the observed results confirmed the simple synthesis of S1 as a promising material for the development of test strip-based sensor devices for the detection of toxic and explosive aromatic nitro molecules.
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http://dx.doi.org/10.1016/j.envres.2021.110741DOI Listing
March 2021

Surface functionalized highly porous date seed derived activated carbon and MoS nanocomposites for hydrogenation of CO into formic acid.

J Hazard Mater 2021 May 25;409:124980. Epub 2020 Dec 25.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

In recent years, substantial progress has been made towards developing effective catalysts for the hydrogenation of CO into fuels. However, the quest for a robust catalyst with high activity and stability still remains challenging. In this study, we present a cost-effective catalyst composed of MoS nanosheets and functionalized porous date seed-derived activated carbon (f-DSAC) for hydrogenation of CO into formic acid (FA). As-fabricated MoS/f-DSAC catalysts were characterized by FE-SEM, XRD, Raman, FT-IR, BET, and CO-TPD analyses. At first, bicarbonate (HCO) was successfully converted into FA with a high yield of 88% at 200 °C for 180 min under 10 bar H atmosphere. A possible reaction pathway for the conversion of HCO into FA is postulated. The catalyst has demonstrated high activity and long-term stability over five consecutive cycles. Additionally, MoS/f-DSAC catalyst was effectively used for the conversion of gaseous CO into FA at 200 °C under 20 bar (CO/H = 1:1) over 15 h. The catalyst exhibited a remarkable TOF of 510 h with very low activation energy of 12 kJ mol, thus enhancing the catalytic conversion rate of CO into FA. Thus, this work demonstrates the MoS/f-DSAC nanohybrid system as an efficient non-noble catalyst for converting CO into fuels.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124980DOI Listing
May 2021

Kinetics and degradation of camphene with OH radicals and its subsequent fate under the atmospheric O and NO radicals - A theoretical study.

Chemosphere 2021 Mar 11;267:129250. Epub 2020 Dec 11.

Petroleum and Chemical Engineering, Faculty of Engineering, Universiti Teknologi Brunei, Bandar Seri Begawan, BE1410, Brunei Darussalam.

Camphene (CH) is an abundant bicyclic monoterpene in the atmosphere which can be easily oxidized by the atmospheric OH radicals. In this study, the oxidation of camphene with OH radicals and its subsequent reactions are studied using quantum chemical method. Thermochemical parameters show that the addition of OH radicals to the terminal C10 atom of camphene is thermodynamically more stable than the addition of OH radicals to the internal C7 atom of camphene. The reaction force profile demonstrates that the formation of two hydroxyalkoxy radical intermediates (I1a and I2a) are mainly dominated by the structural rearrangement with 94.28% and 99.43% of the total energy, respectively. The overall reaction rate coefficient for camphene + OH radical is 2.1⨯10 cm molecule sec at 298 K and 1 atm which agree well with the experimental reaction rate coefficient (5.58⨯10 cm molecule sec) for the reaction of camphene with OH radical. The branching ratio for the addition of OH radical to the C10 position of camphene is 68.32%, and the C7 position of camphene is 31.68% at 298 K. The calculated lifetime reveals that camphene degrades quickly in the atmosphere owing to its short lifetime of 5.3 h. The obtained mechanistic and kinetic results reveal that the addition of OH radical to the C10 position is more dominant than the C7 position, and it is more stable and spontaneous in the atmosphere.
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http://dx.doi.org/10.1016/j.chemosphere.2020.129250DOI Listing
March 2021

Production of copper nanoparticles exhibiting various morphologies via pulsed laser ablation in different solvents and their catalytic activity for reduction of toxic nitroaromatic compounds.

J Hazard Mater 2021 05 28;409:124412. Epub 2020 Oct 28.

Department of Chemistry (BK21 FOUR) and Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Republic of Korea. Electronic address:

Comparative experiments were conducted to determine the effects of various solvents (i.e., deionized water, methanol, ethanol, 1-propanol, butanol, ethylene glycol, hexane, and acetonitrile) on the final compositions, morphologies, and catalytic activities of copper-based nanoparticles (NPs). The NPs were effectively synthesized by pulsed laser ablation (PLA) using a copper plate as the target. The obtained copper NPs were characterized utilizing various analytical techniques. It was established that the developed methodology allows for the production of NPs with different morphologies and compositions in a safe and simple manner. When laser ablation of a solid copper plate was performed in acetonitrile, the formation of copper(I) cyanide cubes was observed. On the other hand, in deionized water and methanol, spherical and rod-like particles of copper(I) and copper(II) oxide were detected, respectively. The catalytic activity of the prepared copper NPs in the reduction of aromatic nitro compounds, such as 4-nitrophenol and nitrobenzene, was also evaluated. A high k value was determined for the reduction over the copper(II) oxide NPs produced in methanol. Moreover, particles with graphitic carbon (GC) layers exhibited superior catalytic performance in the reduction of a hydrophobic substance, i.e., nitrobenzene, over the reduction of 4-nitrophenol. The enhanced catalytic activity of this catalyst may be due its unique surface morphology and the synergistic effects between the copper nanostructure and the GC layer. Lastly, a detailed reduction pathway mechanism for the catalytic reduction of 4-nitrophenol and nitrobenzene has been proposed.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124412DOI Listing
May 2021

Cost-Effective Synthesis of Efficient CoWO/Ni Nanocomposite Electrode Material for Supercapacitor Applications.

Nanomaterials (Basel) 2020 Nov 4;10(11). Epub 2020 Nov 4.

Department of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University, Jinju 52828, Korea.

In the present study, the synthesis of CoWO (CWO)-Ni nanocomposites was conducted using a wet chemical method. The crystalline phases and morphologies of the Ni nanoparticles, CWO, and CWO-Ni composites were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDAX). The electrochemical properties of CWO and CWO-Ni composite electrode materials were assessed by cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) tests using KOH as a supporting electrolyte. Among the CWO-Ni composites containing different amounts of Ni1, Ni2, and Ni3, CWO-Ni3 exhibited the highest specific capacitance of 271 F g at 1 A g, which was greater than that of bare CWO (128 F g). Moreover, the CWO-Ni3 composite electrode material displayed excellent reversible cyclic stability and maintained 86.4% of its initial capacitance after 1500 discharge cycles. The results obtained herein demonstrate that the prepared CWO-Ni3 nanocomposite is a promising electrode candidate for supercapacitor applications.
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http://dx.doi.org/10.3390/nano10112195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7692640PMC
November 2020

Enhanced photocatalytic activity at multidimensional interface of [email protected]/3D-BiOI ternary nanocomposites for tetracycline degradation under visible-light.

J Hazard Mater 2021 02 5;404(Pt B):123868. Epub 2020 Sep 5.

Department of Chemistry (BK21 FOUR) and Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Republic of Korea. Electronic address:

Structural dimensionality and surface morphology are key properties that greatly affect the functionalities of materials. Herein, we report a synthesis of dimensionally coupled ternary nanocomposites from three-dimensional (3D) bismuth oxyiodide (BiOI), two-dimensional (2D) graphene oxide (GO), and one-dimensional (1D) bismuth sulfide (BiS) nanomaterials for tetracycline degradation under visible-light irradiation. The 2%[email protected]%-GO/BiOI ternary nanocomposites show higher degradation efficiency than neat 3D-BiOI. The coupling of neat 1D-BiS with the 1%-GO/BiOI binary nanocomposite does not increase the specific surface area of the resulting 2%[email protected]%-GO/3D-BiOI ternary nanocomposite, but enhances notably its charge carrier separation and migration, according to the analysis of the higher photocurrent, smaller arc radius of the electrochemical impedance spectroscopy and lower photoluminescence intensity. The observed results suggest that the combination of dimensionally coupled composites provides a synergistic effect through an efficient charge transfer process. This work offers new insights into the design and construction of dimensionally coupled ternary nanocomposites for environmental remediation applications.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123868DOI Listing
February 2021

Ionic Liquid-Based Electrolytes for Energy Storage Devices: A Brief Review on Their Limits and Applications.

Polymers (Basel) 2020 Apr 15;12(4). Epub 2020 Apr 15.

Division of Electronics and Electrical Engineering, Dongguk University-Seoul, Seoul 04620, Korea.

Since the ability of ionic liquid (IL) was demonstrated to act as a solvent or an electrolyte, IL-based electrolytes have been widely used as a potential candidate for renewable energy storage devices, like lithium ion batteries (LIBs) and supercapacitors (SCs). In this review, we aimed to present the state-of-the-art of IL-based electrolytes electrochemical, cycling, and physicochemical properties, which are crucial for LIBs and SCs. ILs can also be regarded as designer solvents to replace the more flammable organic carbonates and improve the green credentials and performance of energy storage devices, especially LIBs and SCs. This review affords an outline of the progress of ILs in energy-related applications and provides essential ideas on the emerging challenges and openings that may motivate the scientific communities to move towards IL-based energy devices. Finally, the challenges in design of the new type of ILs structures for energy and environmental applications are also highlighted.
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http://dx.doi.org/10.3390/polym12040918DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7240671PMC
April 2020

Nanofiber NiMoO/g-CN Composite Electrode Materials for Redox Supercapacitor Applications.

Nanomaterials (Basel) 2020 Feb 23;10(2). Epub 2020 Feb 23.

Department of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University, Jinju 52828, Korea.

NiMoO/g-CN was fabricated by a hydrothermal method and used as an electrode material in a supercapacitor. The samples were characterized by XRD, FTIR, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to study the physical and structural properties of the as-prepared NiMoO/g-CN material. The electrochemical responses of pristine NiMoO and the NiMoO/g-CN nanocomposite material were investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). From the CD studies, the NiMoO/g-CN nanocomposite revealed a higher maximum specific capacitance (510 Fg) in comparison to pristine NiMoO (203 Fg). In addition, the NiMoO/g-CN composite electrode material exhibited high stability, which maintained up to 91.8% capacity even after 2000 charge-discharge cycles. Finally, NiMoO/g-CN was found to exhibit an energy density value of 11.3 Whkg. These findings clearly suggested that NiMoO/g-CN could be a suitable electrode material for electrochemical capacitors.
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http://dx.doi.org/10.3390/nano10020392DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075326PMC
February 2020

Sonoelectrochemistry for energy and environmental applications.

Ultrason Sonochem 2020 May 20;63:104960. Epub 2020 Jan 20.

Hydrogen Energy and Sonochemistry Research Group, Department of Energy and Process Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway. Electronic address:

Sonoelectrochemistry is the study of the effects and applications of ultrasonic waves on electrochemical processes. The integration of ultrasound and electrochemistry offers many advantages: fast reaction rates, enhanced surface activation, and increased mass transport at an electrode. Significant progress has been made in advancing basic and applied aspects of sonoelectrochemical techniques, which are herein reviewed by addressing the development and applications of sonoelectrochemical processes in energy and environmental areas. This review examines the experimental procedures that are used in various sonoelectrochemical techniques generally used for the synthesis of energy related materials (e.g., fuel cell electrocatalysts and materials for hydrogen production) and for the degradation of various organic compounds/pollutants. The challenges that remain for the sonoelectrochemical production of energy materials, the degradation of organic pollutants, and their associated reaction pathway mechanism(s) are also discussed. This review also highlights the significant improvements made to date. The provided information in this review may be helpful to scientists working in the research areas of environmental remediation, energy exploitation and exploration, as well as synthetic process-oriented research.
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http://dx.doi.org/10.1016/j.ultsonch.2020.104960DOI Listing
May 2020

Highly Electroactive Ni Pyrophosphate/Pt Catalyst toward Hydrogen Evolution Reaction.

ACS Appl Mater Interfaces 2019 Feb 23;11(5):4969-4982. Epub 2019 Jan 23.

Institute of Chemistry , Universidade Federal de Mato Grosso do Sul , Senador Filinto Muller Avenue, 1555 , Campo Grande , Mato Grosso do Sul 79074-460 , Brazil.

Robust electrocatalysts toward the resourceful and sustainable generation of hydrogen by splitting of water via electrocatalytic hydrogen evolution reaction (HER) are a prerequisite to realize high-efficiency energy research. Highly electroactive catalysts for hydrogen production with ultralow loading of platinum (Pt) have been under exhaustive exploration to make them cutting-edge and cost-effectively reasonable for water splitting. Herein, we report the synthesis of hierarchically structured nickel pyrophosphate (β-NiPO) by a precipitation method and nickel phosphate (Ni(PO)) by two different synthetic routes, namely, simple cost-effective precipitation and solution combustion processes. Thereafter, Pt-decorated nickel pyrophosphate and nickel phosphate (β-NiPO/Pt and Ni(PO)/Pt) were prepared by using potassium hexachloroplatinate and ascorbic acid. The fabricated novel nickel pyrophosphate and nickel phosphate/Pt materials were utilized as potential and affordable electrocatalysts for HER by water splitting. The detailed electrochemical studies revealed that the β-NiPO/Pt (1 μg·cm Pt) electrocatalyst showed excellent electrocatalytic performances for HER in acidic solution with an overpotential of 28 mV at -10 mA·cm, a Tafel slope of 32 mV·dec, and an exchange current density ( j) of -1.31 mA·cm, which were close to the values obtained using the Vulcan/Pt (8.0 μg·cm Pt), commercial benchmarking electrocatalyst with eight times higher Pt amount. Furthermore, the β-NiPO/Pt electrocatalyst maintains an excellent stability for over -0.1 V versus RHE for 12 days, keeping j equal after the stability test (-1.28 mA cm). Very well-distributed Pt NPs inside the "cages" on the β-NiPO structure with a crystalline pattern of 0.67 nm distance to the NiPO/Pt electrocatalyst, helping the Volmer-Tafel mechanism with the Tafel reaction as a major rate-limiting step, help to liberate very fast the Pt sites after HER. The high electrocatalytic performance and remarkable durability showed the β-NiPO/Pt material to be a promising cost-effective electrocatalyst for hydrogen production.
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http://dx.doi.org/10.1021/acsami.8b18153DOI Listing
February 2019

Recent Advances in Metal Chalcogenides (MX; = , ) Nanostructures for Electrochemical Supercapacitor Applications: A Brief Review.

Nanomaterials (Basel) 2018 Apr 19;8(4). Epub 2018 Apr 19.

Division of Electronics and Electrical Engineering, Dongguk University-Seoul, Seoul 04620, Korea.

Supercapacitors (SCs) have received a great deal of attention and play an important role for future self-powered devices, mainly owing to their higher power density. Among all types of electrical energy storage devices, electrochemical supercapacitors are considered to be the most promising because of their superior performance characteristics, including short charging time, high power density, safety, easy fabrication procedures, and long operational life. An SC consists of two foremost components, namely electrode materials, and electrolyte. The selection of appropriate electrode materials with rational nanostructured designs has resulted in improved electrochemical properties for high performance and has reduced the cost of SCs. In this review, we mainly spotlight the non-metallic oxide, especially metal chalcogenides (MX; = , ) based nanostructured electrode materials for electrochemical SCs. Different non-metallic oxide materials are highlighted in various categories, such as transition metal sulfides and selenides materials. Finally, the designing strategy and future improvements on metal chalcogenide materials for the application of electrochemical SCs are also discussed.
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http://dx.doi.org/10.3390/nano8040256DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5923586PMC
April 2018

Highly active MoS/carbon electrocatalysts for the hydrogen evolution reaction - insight into the effect of the internal resistance and roughness factor on the Tafel slope.

Phys Chem Chem Phys 2017 Jan;19(3):1988-1998

Department of Zoology, Bharathiar University, Coimbatore-641 046, Tamilnadu, India.

Molybdenum disulphide (MoS) nanomaterials are promising non-precious-metal electrocatalysts for the hydrogen evolution reaction. MoS/carbon electrocatalysts have been synthesized with the carbon component serving the purpose of enhancing electron transport. The impedance method of Tafel analysis has been employed to evaluate the efficiency of various carbon supports in aiding facile electron transport. A MoS/carbon nanofiber electrocatalyst has been found to be the most active towards hydrogen evolution with the lowest Tafel slope among the investigated electrocatalysts. Tafel analysis indicates that the hydrogen evolution reaction occurs through the Volmer-Heyrovsky mechanism with a rate determining Heyrovsky step in the MoS and MoS/carbon electrocatalysts. Orderly variation of the Tafel slope with the mass loading has been observed in MoS/Vulcan carbon and the cause for this has been investigated based on roughness factor measurements. A linear dependence of the Tafel slope on the roughness factor points to a concomitant increase in the limitations on mass transport. The results show that the benefit of increasing the roughness factor of the electrocatalyst is counterbalanced by increasing the Tafel slope, and hence the need for designing an optimal HER electrocatalyst balancing the roughness factor and Tafel slope is deduced.
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http://dx.doi.org/10.1039/c6cp07416bDOI Listing
January 2017
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