A remarkable three-component RuO2-MnCo2O4/rGO nanocatalyst towards methanol electrooxidation

A three-part nano-catalyst including ruthenium oxide, manganese cobalt oxide, and reduced graphene oxide nanosheet in form of RuO2-MnCo2O4/rGO is synthesized by one-step hydrothermal synthesis. The material is placed on a glassy carbon electrode (GCE) for electrochemical studies. The ability of these nano-catalysts in the oxidation process of methanol in an alkaline medium for usage in direct methanol fuel cells (DMFC) was examined with electrochemical tests of cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The effect of the addition of rGO to the nanocatalyst structure in the methanol oxidation reaction (MOR) process was investigated. We introduced the RuO2-MnCo2O4/rGO as a nanocatalyst with excellent cyclic stability of 97% after 5000 cycles in the MOR process. Besides, the study of the Tafel plots and the effect of temperature and scan rate in the MOR process showed that RuO2-MnCo2O4/rGO nanocatalyst has better electrochemical properties than MnCo2O4 and RuO2-MnCo2O4. This high electrocatalytic activity could be related to the synergistic effect of placement of metal oxides of ruthenium, manganese, and cobalt near each other and putting them on rGO, which enhances conductivity and surface area and improve electron transfer. The decrease in the resistance against charge transfer and the increment in the anodic current density illustrated that the reaction rate is enhanced at higher temperature. Thus RuO2-MnCo2O4/rGO shows robust stability and superior performance for MOR

ANN-LIBS analysis of mixture plasmas: detection of xenon

We developed an artificial neural network method for characterising crucial physical plasma parameters (i.e., temperature, electron density) in a fast and precise manner that mitigates common issues arising in evaluation of LIBS spectra.</jats:p

Main spectral features of meteors studied using a terawatt-class high-power laser

Context. Meteor spectra are commonly interpreted using data from databases and tables. Several studies have demonstrated very sophisticated calculations of elemental compositions of meteoroid bodies based on the computation of synthetic meteor spectra or on the spectral analysis of airglow plasma containing evaporated, atomized, and ionized meteoroid matter. However, considering accuracy, reliability of computations, lack of laboratory experimental data in this field, as well as the complicated physical structure of meteor plasma, such qualitative assignment or quantitative calculations are still extensively discussed in the scientific community. Even on the laboratory level, many studies have shown the high complexity of the acquisition and interpretation of the data that are recorded with techniques of emission spectroscopy that are in fashion and philosophy similar to the spectral analysis of meteor plasma, that is, detection and quantification of the elements that are ablated from complicated multicomponent matrices. Aims. The current study is focused on the application of terawatt-class laser-induced breakdown spectroscopy (TC-LIBS) of real samples of chondritic meteorites. We recorded emission spectra with high resolution and high precision that contain spectral lines that are typical for real meteoric spectra. Experimental data were compiled in a form that is convenient for the meteoric spectra interpretation and calibration. Methods. TC-LIBS was carried out by a high-power terawatt-class laser facility, the Prague Asterix Laser System (PALS). The spectra were simultaneously recorded by an echelle high-resolution spectrograph in the UV/VIS spectral ranges and by a low-resolution spectrograph that was used for real observation of meteor spectra. We also present calculated synthetic spectra based on data from the NIST atomic spectra database. Results. We assembled etalon qualitative tables of major meteoric spectral features that can be used both for the spectral wavelength calibration of low-resolution observational instruments and for the exact interpretation of meteor spectra. The data are compared with real meteor spectra

Prebiotic synthesis initiated in formaldehyde by laser plasma simulating high-velocity impacts

Context. It is well known that hydrogen cyanide and formamide can universally be considered as key molecules in prebiotic synthesis. Despite the fact that formamide has been detected in interplanetary and interstellar environments, other prebiotic species are far more abundant, including, for example, formaldehyde. However, several results indicate that formamide can play the role of important intermediate as well as that of a feedstock molecule in chemical abiogenesis. Diverse recently proposed scenarios of the origins of the first biopolymers show that liquid formamide environments could have been crucial for the formation of nucleobases, nucleosides, and for phosphorylation reactions, which lead to nucleotides. Aims. Here we report on a wide exploration of the formaldehyde reaction network under plasma conditions mimicking an asteroid descent in an Earth-like atmosphere and its impact. Methods. Dielectric breakdown using a high-power kJ-class laser system (PALS – Prague Asterix Laser System) along with quantum mechanical, ab initio molecular dynamics, and enhanced sampling simulations have been employed in order to mimic an asteroid impact plasma. Results. Being more abundant than formamide both in interstellar and interplanetary environments, during the era of early and late heavy bombardment of Earth and other planets, formaldehyde might have been delivered on asteroids to young planets. In the presence of nitrogen-bearing species, this molecule has been reprocessed under plasma conditions mimicking the local environment of an impacting body. We show that plasma reprocessing of formaldehyde leads to the formation of several radical and molecular species along with formamide. Conclusion. All the canonical nucleobases, the simplest amino acid (i.e., glycine), and the sugar ribose, have been detected after treatment of formaldehyde and nitrogen gas with dielectric breakdown. Our results, supported by quantum mechanical and enhanced sampling simulations, show that formaldehyde – by producing inter alia formamide – may have had the role of starting substance in prebiotic synthesis