Search results for "NITRIDE"

Lattice dynamics of wurtzite and rocksalt AlN under high pressure: Effect of compression on the crystal anisotropy of wurtzite-type semiconductors

2008

Raman spectra of aluminum nitride (AlN) under pressure have been measured up to $25\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, i.e., beyond the onset of the wurtzite-to-rocksalt phase transition around $20\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. The experimental pressure coefficients for all the Raman-active modes of the wurtzite phase are reported and compared to those obtained from ab initio lattice dynamical calculations, as well as to previous experimental and theoretical results. The pressure coefficients of all the Raman-active modes in wurtzite-type semiconductors (AlN, GaN, InN, ZnO, and BeO), as well as the relatively low bulk modulus and phase transition pressure in wurtzite AlN, a…

Photocatalytic CO 2 Valorization by Using Ti O2 , ZrO2 and Graphitic Based Semiconductors

2018

In this century, a broad scientific interest has been devoted to fulfill sustainable industrial processes and climatic change remediation. In this prospective, various green technologies have been studied to valorize CO 2• The aim of this research is the CO 2 reduction in presence of water by using the photocatalytic technology with nanomaterials as the photocatalysts. The present work overviews the main outcomes obtained by using graphitic and oxide based photocatalysts both in gas/solid and liquid/solid batch reactors under simulated solar light. In all gas/solid regime tests the major products detected were methane, carbon monoxide, and acetaldehyde.

Photocatalytic membrane reactor for CO2 conversion

2017

Photocatalytic membrane reactor for CO2 conversion

CO2 conversion in continuous photocatalytic membrane reactor

2017

CO2 conversion in continuous photocatalytic membrane reactor

Changes in surface stress at the liquid/solid interface measured with a microcantilever

2000

Abstract The bending of microfabricated silicon nitride cantilevers was used to determine surface stress changes at solid–liquid interfaces. The radius of curvature of the bent cantilever is directly proportional to changes in the differential surface stress between its opposite sides. To demonstrate the possibilities and limitations of the technique, cantilevers coated on both sides with gold and densely packed monolayers of different thiols were put in a constant flow of aqueous electrolyte solution and the deflection was measured using a optical lever technique. Changes in the surface stress for the different thiol monolayers due to specific proton adsorption are presented. Possible appl…

Temperature and time dependent electron trapping in Al2O3 thin films onto AlGaN/GaN heterostructures

2022

In this article, the charge trapping phenomena in Al2O3 thin films grown by atomic layer deposition (ALD) on AlGaN/GaN heterostructures have been studied by time-dependent capacitance–voltage (C-V) measurements as a function of temperature. In particular, monitoring the transient of the capacitance enabled us to estimate the maximum depth of the insulating layer interested by the negative charge trapping effect under our bias stress conditions and to determine a charge traps density in the bulk Al2O3 in the order of 3 × 1019 cm−3. A temperature dependent C-V analysis up to 150 °C demonstrated the presence of two competitive mechanisms that rule the electron capture and emission in the Al2O3…

Carbon nitride nanosheets for the selective photocatalytic oxidation of 5-hydroxymethyl-2-furfural to 2,5-furandicarboxyaldehyde in water suspension

2017

Carbon nitride nanosheets for the selective photocatalytic oxidation of 5-hydroxymethyl-2-furfural to 2,5-furandicarboxyaldehyde in water suspension

Carbon nitride-hydrogen peroxide adduct for selective photo-oxidation

Application of thermally exfoliated g-C3N4 for a green selective photocatalytic oxidation of 5-hydroxymethyl-2-furfural

2016

Graphitic carbon nitride assisted partial photocatalytic oxidation of 5-hydroxymethyl-2-furfural (HMF) in aqueous medium was investigated. Different carbon nitride precursors were considered, being melamine the one yielding the most efficient photocatalyst. The obtained 30% selectivity of HMF oxidation towards 2,5-furandicarboxaldehyde (FDC) is higher than those reported up to now. A further thermal exfoliation of the g-C3N4 samples showed under artificial light irradiation both an enhanced photocatalytic activity in conversion of HMF, and selectivity (ca. 42-45 %) towards FDC. The performance of the catalysts increased when the experiments were carried out under real outdoor illumination, …

Selective photocatalytic oxidation of 5-hydroxymethyl-2-furfural to 2,5-furandicarboxyaldehyde in aqueous suspension of g-C3N4

2017

Graphitic carbon nitride assisted partial photocatalytic oxidation of 5-hydroxymethyl-2-furfural (HMF) in aqueous medium was investigated. Different carbon nitride precursors were considered, being melamine the one yielding the most efficient photocatalyst. The obtained 30% selectivity of HMF oxidation to 2,5-furandicarboxaldehyde (FDC) is higher than those reported up to now. A further thermal exfoliation of the g-C3N4 samples showed under artificial light irradiation both an enhanced photocatalytic activity in conversion of HMF, and selectivity (ca. 42–45%) to FDC. The performance of the catalysts increased when the experiments were carried out under real outdoor illumination, reaching 50…