Band alignment at GaxIn1-xP/AlyIn1-yP alloy interfaces from hybrid density functional theory calculations. - In: Physica status solidi, ISSN 1521-3951, Bd. 258 (2021), 2, 2000463, insges. 4 S.
The composition dependence of the natural band alignment at the GaxIn1-xP/AlyIn1-yP alloy interface is investigated via hybrid functional based density functional theory. The direct-indirect crossover for the GaxIn1-xP and AlyIn1-yP alloys is calculated to occur for x = 0.9 and y = 0.43. The calculated GaxIn1-xP/AlyIn1-yP interface band alignment shows a crossover from type-I to type-II with increasing Ga content x. The valence band offset is essentially positive irrespective of the alloy compositions, and amounts up to 0.56 eV. The conduction band offset varies between −0.85 and 1.16 eV.
https://doi.org/10.1002/pssb.202000463
Substitutionally dispersed high-oxidation CoOx clusters in the lattice of rutile TiO2 triggering efficient Co-Ti cooperative catalytic centers for oxygen evolution reactions. - In: Advanced functional materials, ISSN 1616-3028, Bd. 31 (2021), 9, 2009610, insges. 13 S.
Im Titel sind "x" und "2" tiefgestellt
The development of economical, highly active, and robust electrocatalysts for oxygen evolution reaction (OER) is one of the major obstacles for producing affordable water splitting systems and metal-air batteries. Herein, it is reported that the subnanometric CoOx clusters with high oxidation state substitutionally dispersed in the lattice of rutile TiO2 support (Co-TiO2) can be prepared by a thermally induced phase segregation process. Owing to the strong interaction of CoOx clusters and TiO2 support, Co-TiO2 exhibits both excellent intrinsic activity and durability for OER. The turnover frequency of Co-TiO2 is up to 3.250 s-1 at overpotentials of 350 mV; this value is one of the highest in terms of OER performance among the current Co-based active materials under similar testing conditions; moreover, the OER current density loss is only 6.5% at a constant overpotential of 400 mV for 30 000 s, which is superior to the benchmark Co3O4 and RuO2 catalysts. Mechanism analysis demonstrates that charge transfer occurs between Co sites and their neighboring Ti atoms, triggering the efficient Co-Ti cooperative catalytic centers, in which OH* and O* are preferred to be adsorbed on the bridging sites of Co and Ti with favorable adsorption energy, inducing a lower energy barrier for O2 generation.
https://doi.org/10.1002/adfm.202009610
A method to approach constant isotropic permeabilities and demagnetization factors of magneto-rheological elastomers. - In: Journal of magnetism and magnetic materials, ISSN 1873-4766, Bd. 527 (2021), 167742
The use of non-conventional materials is nowadays of much interest in scientific community. Magneto-rheological elastomers are hybrid materials, which in presence of magnetic fields state a change in their mechanical properties. They are composed by an elastomeric matrix with embedded magnetic particles. One of the most attractive features of these materials is that as soon as the magnetic field is removed from the material, the original mechanical properties are completely recovered, with negligible differences in comparison to the original state. This paper focuses on the study of magnetic characteristics of these smart materials, such as relative permeability and demagnetizing factors, for samples with different volume concentration of ferromagnetic particles.
https://doi.org/10.1016/j.jmmm.2021.167742
Photo-thermoelectric conversion using black silicon with enhanced light trapping performance far beyond the band edge absorption. - In: ACS applied materials & interfaces, ISSN 1944-8252, Bd. 13 (2021), 1, S. 1818-1826
https://doi.org/10.1021/acsami.0c17279
Effect of thermoplastic morphology on mechanical properties in laser-assisted joining of polyamide 6 with aluminum. - In: Welding in the world, ISSN 1878-6669, Bd. 65 (2021), 4, S. 699-711
This paper examined the joining zone between semi-crystalline polyamide 6 and aluminum EN AW 6082 in laser-based joining and evaluated the mechanical properties of the joint. The joint tests were carried out in overlap configuration and a characterized in terms of energy per unit length. The mechanical properties were examined to the point of cohesive failure. An increasing energy per unit length resulted in a reduced crosshead displacement in short-term testing and a decreased fatigue strength. Further material testing was carried out locally at various positions within the joining zone. The mechanical properties were correlated with results of a hardness test, thermoplastic morphology, differential scanning calorimetry (DSC), and X-ray diffraction (XRD). By combining the findings with heat-treated samples at elevated temperatures, secondary crystallization was identified and evidenced as a primary effect among the changes in mechanical properties due to the heat treatment of the thermoplastic material.
https://doi.org/10.1007/s40194-020-01048-1
Layer-by-layer polyelectrolyte assembly for the protection of GaP surfaces from photocorrosion. - In: ACS applied nano materials, ISSN 2574-0970, Bd. 4 (2021), 1, S. 425-431
Polyelectrolyte layer-by-layer assemblies are known as protective coatings for corrosion inhibition. Here, we demonstrate that polyelectrolyte multilayers of poly(ethyleneimine) (PEI) and poly(styrene sulfonate) (PSS)-(PEI/PSS)x-adsorbed at the GaP(100) photocathode surface remarkably mitigate the photocorrosion of GaP without decreasing its photoconversion efficiency. The activity of the polybase-polyacid complex is based on buffering pH changes at the solid-liquid interface. We carried out ab initio molecular dynamics-based simulations of the GaP(100) surface in contact with liquid water and demonstrated that an increase in the proton concentration enhances GaP dissolution. We used the scanning vibrating electrode technique (SVET) to characterize the distribution of photocorrosion activity areas over bare and polyelectrolyte-coated GaP surfaces and we showed that a polyelectrolyte coating impedes the dissolution kinetics. Data obtained using the SVET were compared to photoetched pores on the semiconductor surface. Voltammetric and chronoamperometric measurements were also performed to evaluate photoconversion efficiencies before and after the application of the protective coatings.
https://doi.org/10.1021/acsanm.0c02768
Electrocatalysis of lithium (poly-) sulfides in organic ether-based electrolytes. - In: Journal of the Electrochemical Society, ISSN 1945-7111, Bd. 167 (2021), 16, 166520, insges. 9 S.
https://doi.org/10.1149/1945-7111/abd60c
Method for contact resistance determination of copper during fast temperature changes. - In: Journal of materials science, ISSN 1573-4803, Bd. 56 (2021), 5, S. 3827-3845
https://doi.org/10.1007/s10853-020-05490-w
Formation of CuCrCoFeNiO high entropy alloy thin films by rapid thermal processing of Cu/CrNiO/FeCo multilayers. - In: Surface and coatings technology, ISSN 1879-3347, Bd. 405 (2021), 126563
https://doi.org/10.1016/j.surfcoat.2020.126563
Electrocodeposition of Ni composites and surface treatment of SiC nano-particles. - In: Surface and coatings technology, ISSN 1879-3347, Bd. 406 (2021), 126663, insges. 8 S.
https://doi.org/10.1016/j.surfcoat.2020.126663