Search

[Display omitted] • Acoustic levitation coupled with pulsed laser irradiation process. • Free-standing nanocatalysts synthesis via hybrid acoustic levitation/PLI process. • Au NPs showed excellent catalytic behavior towards 4-nitrophenol reduction. • Formation of NPs and chemical reactions monitored by in situ spectroscopic techniques. Acoustic levitation is a distinctive and versatile tool for levitating and processing free-standing single droplets and particles. Liquid droplets suspended in an acoustic standing wave provide container-free environments for understanding chemical reactions by avoiding boundary effects and solid surfaces. We attempted to use this strategy for the production of well-dispersed uniform catalytic nanomaterials in an ultraclean confined area without the addition of external reducing agents or surfactants. In this study, we report on the synthesis of gold and silver nanoparticles (NPs) via acoustic levitation coupled with pulsed laser irradiation (PLI). In situ UV–Visible and Raman spectroscopic techniques were performed to monitor the formation and growth of gold and silver NPs. The PLI was used for the photoreduction of targeted metal ions present in the levitated droplets to generate metal NPs. Additionally, the cavitation effect and bubble movement accelerate the nucleation and decrease the size of NPs. The synthesized Au NPs with ∼ 5 nm size showed excellent catalytic behavior towards the conversion of 4-nitrophenol to 4-aminophenol. This study may open a new door for synthesizing various functional nanocatalysts and for achieving new chemical reactions in suspended droplets. [ABSTRACT FROM AUTHOR]

Mass-selected resonant two-photon ionization (R2PI) and UV–UV hole-burning, and infrared-dip spectra of 5-cyanoindole (5CI) and its water clusters, 5CI–(H 2 O) n ( n = 1 and 2) were measured. Although, the structures of 5CI–(H 2 O) 1–2 are similar to those of 3CI–(H 2 O) 1–2 , the photofragmentation behaviors of the two systems are quite different due to the L a –L b state energy lowering and higher binding energies of 5CI–(H 2 O) 1–2 compared to those of 3CI–(H 2 O) 1–2 . Especially for the case of 5CI–(H 2 O) 2 cluster, shortening excited-state lifetime of 5CI–(H 2 O) 2 causes the broad background in the R2PI spectrum of 5CI–(H 2 O) 2 . [ABSTRACT FROM AUTHOR]

The conformational structure of indole-3-carbinol (I3C) has been investigated in the gas phase for the first time using a laser desorption technique. A UV–UV hole-burning technique revealed the presence of a single conformer of I3C in the mass-selected resonant two-photon ionization spectrum. The assignment of the observed IR spectrum of I3C is inconclusive due to almost identically predicted IR frequencies of the two lowest energy conformers from harmonic calculations. A conclusive assignment for the conformer of I3C has been reported with an aid of performing anharmonic calculations and Franck–Condon simulations on the two lowest-energy conformers. [ABSTRACT FROM AUTHOR]

Franck–Condon (FC) simulations were applied to 3-cyanoindole (3CI) and its water clusters, 3CI-(H 2 O) n ( n = 1 and 2), for the first time to determine their molecular structures using mass-selected resonant two-photon ionization (R2PI) and UV–UV hole-burning (UVHB) spectroscopy. R2PI and UVHB spectra were compared with the results of Franck–Condon (FC) simulations that can determine the change in a molecular geometry of 3CI-(H 2 O) n ( n = 0–2) on electronic excitation. It was found that the most stable structure for each 3CI-(H 2 O) n ( n = 0–2) was identified and their excited state geometries were little influenced upon excitation. [ABSTRACT FROM AUTHOR]

The excitation spectra of 3-cyanoindole (3CI) and its water clusters, 3CI-(H 2 O) n ( n = 1 and 2), have been measured by mass-selected resonant two-photon ionization and UV–UV hole-burning (UVHB) spectroscopy. The observed spectra are compared with the predictions of ab initio and density functional theory calculations. The comparison suggests that the spectra arise from a single conformer of 3CI and two conformers of 3CI-(H 2 O) n ( n = 1 and 2) each. UVHB and IR-dip spectroscopy were employed to identify the conformers of 3CI-(H 2 O) 1 and 3CI-(H 2 O) 2 . The conformation-specific structural assignment of the conformers is compared and discussed with theoretical calculations. [ABSTRACT FROM AUTHOR]

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. • Dechlorination experiments was carried out using pulsed laser irradiation process. • Dechlorination efficiency was optimized by controlling laser parameters. • Optimal irradiation conditions are multi pathway system with wavelength at 266 nm. • Present technology can be applied for various chlorine-based pollutants degradation. [ABSTRACT FROM AUTHOR]

By driving the electrooxidation of small molecules instead of relying on sluggish oxygen evolution reaction (OER), low-input voltage is obtained for overall water splitting (OWS) and hydrogen generation, requiring active electrocatalysts. Using single-step pulsed laser irradiation, strong metal-support interaction is achieved on Pd/PdO-decorated Ni 3 (PO 4) 2 ·8H 2 O (NiPh) microflowers, yielding an outstanding bifunctional electrocatalyst for hydrogen evolution (HER) and hydrazine oxidation (HzOR). When Pd/PdO-NiPh-3 serves as both anode and cathode in the OWS electrolyzer (OER||HER), a cell voltage of 2.098 V achieves 10 mA/cm2 in 1.0 M KOH. When evaluated in the hydrazine-coupled electrolyzer (HzOR||HER), Pd/PdO-NiPh-3 exhibits remarkable stability with a low cell voltage of 0.538 V in 0.5 M-N 2 H 4 /1.0 M-KOH, which is approximately 1.56 V lower than that of the traditional water electrolyzers. In Pd/PdO-NiPh, the empty 4 s and 5 s orbitals of Ni2+ and Pd, respectively, serve as two absorption sites. These sites facilitate chemisorption on the electrocatalyst surface by forming a two-electron dipolar bond between the lone-pair electrons of NH 2 groups in N 2 H 4 and Ni2+ as well as Pd. A feasible strategy for utilizing Pd/PdO-NiPh catalysts in developing direct N 2 H 4 fuel cells is investigated in this work, enabling the simultaneous production of robust energy-saving H 2 fuel and electricity. • Leveraging phosphate group in Pd/PdO-nickel phosphate via pulsed laser. • Hydrazine-coupled electrolyzer for energy-saving high-rate H 2 fuel production. • Pd/PdO-NiPh ∥ Pd/PdO-NiPh require only 0.53 V for OHzS and 2.09V for OWS. • PO 4 group in NiPh supplies abundant electrons for electrocatalytic active-states. [ABSTRACT FROM AUTHOR]

Design and optimizing the components and structure of highly-active electrocatalysts is a prevalent approach for reducing the input electrical energy consumption and concurrently H 2 fuel production. An efficient and sustainable method is a water-electrolyzer for H 2 generation, but still restricted by the stable electrode materials. In this study, a green chemistry approach for one-pot production of Pt/C nanospherical with controllable ratios of Pt and C was demonstrated using simple pulsed laser ablation in liquid (PLAL) process, during which Pt target ablation in diverse solvents (water, methanol, ethanol, and 1-propanol) without external carbon source and reducing/capping agents. The carbon-rich solvents are acted as both C-source and solvent, which are decomposed during the PLAL process, producing C, H, and OH ions inside the cavitation bubble which condenses as C-shells on the Pt surface. The optimal Pt/C proportions have the highest electrochemical H 2 -evolution in acidic media with an overpotential of 59 mV at 10 mA/cm2, Tafel slope of 41 mV/dec, and j 0 of 0.686 mA/cm2. The exceptional electrocatalytic concert of optimal Pt/C was further supported by the density functional theory. Optimized C-content in Pt/C reveals good dispersion and strong interaction of C with Pt can make efficient electron transfer, structural stability, and electrochemical durability, resulting in superior electrocatalytic performance in electrolyzer devices. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • AuPtCu nanoalloys produced via green synthesis process of pulsed laser technique. • Optimal AuPtCu show excellent formic acid electro-oxidation in acidic environment. • Formic acid oxidation process catalyzed via direct dehydrogenation path. • Formic acid was directly oxidized to CO 2 while CO was removed by Cu over AuPtCu. The process of hydrogen energy storage via water electrolysis is challenging because of the highly explosive nature of hydrogen gas. To circumvent this issue, the formic acid aqueous solution is being intensively investigated in the field of fuel cells as of its excellent stability and no hazard of combustion or explosion. In formic acid oxidation (FAO), a formic acid solution is decomposed into CO 2 , thus generating hydrogen ions and electrons. This process can occur via two pathways, i.e., with or without CO generation. In this study, we prepared AuPtCu alloys as a catalyst for formic acid fuel cell (FAFC) usage employing an ecofriendly pulsed laser without requiring a reducing agent or surfactant. The FAO process catalyzed by the AuPtCu alloys was found to ensue via a direct path, i.e., dehydrogenation in the existence of Pt and Au. Formic acid was directly oxidized to CO 2 while CO was removed by Cu. The optimal Au1Pt1Cu0.5 catalyst exhibited the best electrochemical FAO activity, outperforming traditional Pt/C, most likely because of the Cu content enhancing the amount of active surface sites. This research demonstrates the potential of AuPtCu for application in direct FAFCs as a power source for transportable devices. [ABSTRACT FROM AUTHOR]

Fabrication of layered triple hydroxides (LTH) is a typical and remarkable approach to produce new functionalities passionately investigated for photocatalytic removal of organic pollutants from industrial wastewater. The hydrothermal method was used to prepare different weight percentages of yttrium (Y) doped NiMgAl LTH. The structural, functional, optical, and morphological properties of the prepared samples were investigated using X-ray diffraction, Fourier transformed-infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, and scanning electron microscopy. The photocatalytic degradation of the different percentages of Y-doped LTH samples were assessed through the photocatalytic degradation of methylene blue dye under the visible light irradiation. When compared to other lower concentrations of Y doping, the photocatalytic degradation efficiency of 1 wt.% Y-doped LTH was higher. Thus, the optimized LTH's improved photocatalytic performance was attributed to increased visible light absorption with low transmission and improved electron-hole separation. [Display omitted] • Fabricated Y3+ doped NiMgAl layered triple hydroxide (LTH) via hydrothermal method. • Efficient removal of MB dye was achieved on 1 wt% of Y@NiMgAl LTH. • Doping of Y3+ with LTH increases the separation of charge carriers. • The charge transfer mechanism of the Y3+ doped LTH was discussed in detail. [ABSTRACT FROM AUTHOR]