1,721,015 research outputs found
Porphyrins in Competition with their Nanomaterials Containing PtNPs and AuNPs. Synergism for the Benefit of Sensing Applications
No full textDue to their amazing optoelectronic properties, porphyrins have intrinsic sensing propertiesthat might be highly improved when they are associated with a proper partner, such as platinumnanoparticles PtNPs or gold nanoparticles AuNPs. [...
Recovery of Waste Industrial Waters Containing Red Congo by Multifunctionalized Mesoporous Silica Nanomaterials
No full textIntroduction: Colored wastewaters, containing toxic dyes, such as Congo red, methylene blue, malachite green, fuchsine B, bromothymol blue, must first focus on the removal of dyes, before any other recovery treatment [...
Catalytic Properties of Free-Base Porphyrin Modified Graphite Electrodes for Electrochemical Water Splitting in Alkaline Medium
No full textHydrogen generation via electrochemical water splitting is considered an eco-friendly pathway for obtaining this desired alternative energy source, and it has triggered an intensive search for low cost and efficient catalysts. Within this context, four free-base porphyrins were studied as heterogeneous catalysts for the oxygen and hydrogen evolution reactions (OER and HER) in alkaline aqueous solutions. TEM and STEM analyses of samples obtained by drop-casting the porphyrins from different organic solvents on TEM grids revealed a rich variety of aggregates due to the self-assembling property of the porphyrin molecules. Modified electrodes were manufactured by applying the four tetrapyrrolic macrocycles from various solvents on the surface of graphite supports, in one or more layers. Experiments performed in 0.1 M and 1 M KOH electrolyte solutions allowed the identification of the most electrocatalytically active electrodes for the OER and HER, respectively. In the first case, the electrode was manufactured by applying three layers of 5-(4-pyridyl)-10,15,20-tris(4-phenoxyphenyl)porphyrin on the graphite substrate from N,N-dimethylformamide solution was identified as overall catalytically superior. In the second case, the electrode obtained by applying one layer of 5,10,15,20-tetrakis(4-allyloxyphenyl)-porphyrin from benzonitrile solution displayed an HER overpotential value of 500 mV at i = −10 mA/cm2 and a Tafel slope of 190 mV/dec
The Optical Properties of Crystalline Zn3Nb2O8 Nanomaterials Obtained by Hydrothermal Method
Get PDFThe present study is focused on the obtaining of the Zn3Nb2O8 nanomaterial using the hydrothermal method and its characterization through different techniques. X-ray diffraction at room temperature revealed that a novel crystalline form of the nanomaterial forms at 1100°C belonging to monoclinic space group C2/c. Field-emission scanning electron microscopy evidenced the columnar morphology of the particle’s agglomeration and the high resolution electron transmission microscopy confirms the measured interplanar distances calculated from the X-ray diffraction experiments. Using the UV-VIS spectrum and Kubelka-Munk equations, the absorbance and the band gap for the Zn3Nb2O8 nanomaterial were calculated. PL spectrum reveals a single peak at 465 nm corresponding to the blue color fluorescence. The novel crystalline nanomaterial might find applications in fluorescence covering of technical devices, due to its capacity to preserve blue fluorescence both in acrylic based paint and after embedding in isopropyl alcohol
(p‐Tolyl)dichlorophosphine and Di(p‐tolyl)chlorophosphine — Sources of New Organophosphorus(III) and (V) Compounds.
No full textHydrothermal synthesis of ZnTa
No full textZnTa2O6, ZnNb2O6, MgTa2O6 and MgNb2O6 pseudo-binary oxide nanomaterials were synthesized through the hydrothermal method at 250 °C. Obtained materials were characterized by X-ray diffraction, UV-VIS measurements, field emission-scanning electron microscopy and atomic force microscopy techniques. XRD results show that the single phases of ZnTa2O6, ZnNb2O6, MgTa2O6 and MgNb2O6 pseudo-binary oxides nanomaterials were obtained, no thermal treatment being required. The values for the optical band gap of each material are settled in the range 3.60–3.80 eV. The anticorrosion characteristics of the obtained compounds were also evaluated after deposition on carbon steel in 0.5 M Na2SO4 media by open circuit potential measurements and potentiodynamic polarization technique with Tafel representation. The inhibition efficiency of pseudo-binary oxides deposited on carbon steel electrode was in the range 37–59.17%, promising for improvement of the anticorrosion properties
JSCS-3232 Original scientific paper
No full textStyrene-divinylbenzene copolymer grafted with phosphonic acid dialkylester
Free Base Porphyrins as Ionophores for Heavy Metal Sensors
No full textTwo functionalized porphyrins: 5,10,15,20-tetrakis(3,4-dimethoxyphenyl) porphyrin (A) and 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (B) obtained and characterized by us were used as ionophores (I) for preparing PVC-based membrane sensors selective to Ag+, Pb2+ and Cu2+. The membranes were prepared using three different plasticizers: (bis(2-ethylhexyl)sebacate (DOS), dioctylphtalate (DOP), o-nitrophenyl octyl ether (NPOE) and potassium tetrakis(4-chlorophenyl)borate (KTClPB) as additive. The functional parameters (linear concentration range, slope and selectivity) of the sensors with membrane composition: (I:PVC:KTClPB:Plasticizer) in different ratios were investigated. The best results were obtained for the membranes in the ratio I:PVC:KTClPB:Plasticizer 10:165:5:330. The influence of pH on the sensors response was studied. The sensors were used for a period of four months and their utility has been tested on synthetic and real samples
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