Constitution and conductivity of metalloporphyrin tapes

Metalloporphyrin tapes form in a solvent-free oxidative chemical vapor deposition process on glass substrates. The metal center (M = NiII, CuII, ZnII, CoII, PdII, FeIIICl, 2H) in the 5,15-disubstituted porphyrin monomer affects the initial C–C coupling step and consequently the formation of triply or doubly linked porphyrin tapes as well as the interchain interaction in the tape as shown by optical spectroscopy, high resolution mass spectrometry and X-ray photoelectron spectroscopy. Optical spectroscopy and conductive atomic force microscopy reveal that these factors influence the near-infrared absorbance and the electrical conductivity of the films. Consequently, the metal ion of the metalloporphyrin allows tuning of the macroscopic properties of the thin films composed of metalloporphyrin tapes

Acetaminophen oxidation under solar light using Fe-BiOBr as a mild Photo-Fenton catalyst

Acetaminophen is an analgesic used as a first-choice treatment for pain and fever. When individuals consume acetaminophen, a portion of the drug is excreted through urine and can end up in wastewater. Water remediation from pharmaceuticals, such as acetaminophen, is required before reaching the environment. This work demonstrates that Fe–BiOBr using the solar photo-Fenton process eliminates acetaminophen at mild pH in aqueous media. Fe-BiOBr is produced using microwave-assisted solvothermal synthesis, and the formation of the BiOBr phase is confirmed with XRD. SEM and TEM demonstrated the flower-like morphology, in which crystallite size reduces as a function of the Fe loading. The chemical environment at the surface of Fe–BiOBr is investigated with XPS. The results are connected with Raman analysis, which suggests the presence of oxygen vacancies in Fe–BiOBr. Furthermore, the effect of Fe in BiOBr is assessed by determining the optical band gap with UV–Vis. The Fe-BiOBr functionality is assessed during acetaminophen degradation. Fe-BiOBr revealed excellent performance in degrading acetaminophen in the first minutes (Q = 10 kJ m −2) under natural sunlight. Results reveal that 1% Fe content in BiOBr can degrade acetaminophen and its main byproduct (30 min, Q = 50 kJ m −2) at pH 5 and using 0.25 gL -1 of catalyst. A synergistic mechanism between heterogeneous photocatalysis and Fenton processes with primary superoxide ( •O 2 –) radical, followed by hydroxyl ( •OH) radical and photogenerated holes (h +), is proposed. Our research contributes to the degradation of pharmaceuticals under mild conditions and sunlight irradiation.</p

Secondary crystalline phases identification in Cu2ZnSnSe4 thin films: contributions from Raman scattering and photoluminescence

In this work, we present the Raman peak positions of the quaternary pure selenide compound Cu2ZnSnSe4 (CZTSe) and related secondary phases that were grown and studied under the same conditions. A vast discussion about the position of the X-ray diffraction (XRD) reflections of these compounds is presented. It is known that by using XRD only, CZTSe can be identified but nothing can be said about the presence of some secondary phases. Thin films of CZTSe, Cu2SnSe3, ZnSe, SnSe, SnSe2, MoSe2 and a-Se were grown, which allowed their investigation by Raman spectroscopy (RS). Here we present all the Raman spectra of these phases and discuss the similarities with the spectra of CZTSe. The effective analysis depth for the common back-scattering geometry commonly used in RS measurements, as well as the laser penetration depth for photoluminescence (PL) were estimated for different wavelength values. The observed asymmetric PL band on a CZTSe film is compatible with the presence of CZTSe single-phase and is discussed in the scope of the fluctuating potentials’ model. The estimated bandgap energy is close to the values obtained from absorption measurements. In general, the phase identification of CZTSe benefits from the contributions of RS and PL along with the XRD discussion.info:eu-repo/semantics/publishedVersio

Atmospheric pressure chemical vapour deposition of transition metal selenide thin films

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Chemical vapour deposition of metalloporphyrins: a simple route towards the preparation of gas separation membranes

The simultaneous polymerisation and chemical vapour deposition (CVD) of metalloporphyrins yield a new class of defect-free and nanoporous layers with outstanding gas separation properties.</p