Balanced, strong interaction of Ni–Na₂O–ZrO₂catalyst components under CO₂reforming of methane is a criterion of good catalytic activity and stability.

The combination of the unique physical properties of molybdenum disulfide (MoS₂) with those of gallium nitride (GaN) and related group-III nitride semiconductors have recently attracted increasing scientific interest for the realization of innovative electronic and optoelectronic devices. A deep understanding of MoS₂/GaN interface properties represents the key to properly tailor the electronic and optical behavior of devices based on this heterostructure. In this study, monolayer (1L) MoS₂ was grown on GaN-on-sapphire substrates by chemical vapor deposition (CVD) at 700 °C. The structural, chemical, vibrational, and light emission properties of the MoS₂/GaN heterostructure were investigated in detail by the combination of microscopic/spectroscopic techniques and ab initio calculations. XPS analyses on as-grown samples showed the formation of stoichiometric MoS₂. According to micro-Raman spectroscopy, monolayer MoS₂ domains on GaN exhibit an average n-type doping of (0.11 ± 0.12) × 10¹³ cm⁻² and a small tensile strain (ε ≈ 0.25%), whereas an intense light emission at 1.87 eV was revealed by PL analyses. Furthermore, a gap at the interface was shown by cross-sectional TEM analysis, confirming the van der Waals (vdW) bond between MoS₂ and GaN. Finally, density functional theory (DFT) calculations of the heterostructure were carried out, considering three different configurations of the interface, i.e., (i) an ideal Ga-terminated GaN surface, (ii) the passivation of Ga surface by a monolayer of oxygen (O), and (iii) the presence of an ultrathin Ga₂O₃ layer. This latter model predicts the formation of a vdW interface and a strong n-type doping of MoS₂, in closer agreement with the experimental observations.

In this study, the surface and textural properties as well as the catalytic performance of Ni/CeO₂ and NiIn/CeO₂ catalysts prepared by wet impregnation (WI) and deposition–precipitation (DP) are investigated. The addition of Ni (3.0 wt.%) resulted in a decrease in the specific surface area and pore volume in the case of the WI method, possibly due to a blockage of mesopores. A minimal addition of In (0.25 wt.%) caused a further decrease in the surface area in both cases. XRD analysis showed that Ni deposited on CeO₂ by DP resulted in some lattice incorporation, affecting the crystallinity of the support. The H₂-TPR profiles altered depending on the different ways of Ni and In introduction. STEM-EDS-derived elemental maps indicated that the Ni and NiIn particles deposited on CeO₂ using the DP method were somewhat smaller than in the WI synthesis. A comprehensive CO-DRIFTS analysis proved a direct Ni-In interaction in bimetallic samples, leading to the formation of a surface NiIn alloy. Ni/CeO₂ catalysts showed a higher activity in the process of dry reforming of methane (DRM) than the bimetallic counterparts at 650 °C, with the Ni_DP sample performing slightly better. However, the Ni_DP catalyst showed significant coking, which was drastically reduced by the addition of In. The agglomeration of Ni and/or NiIn particles during the 6 h DRM reaction somewhat impaired the catalyst performance. Overall, this study highlights the intricate relationship between the catalyst preparation, surface properties and catalytic performance in the DRM reaction and emphasizes the beneficial role of In addition in reducing the coking of the monometallic catalyst and the critical location and surface morphology of nickel nanoparticles decorated with indium and in contact with ceria.

In this study, we examined the chemical changes occurring in ground tire rubber (GTR) and on its surface as a result of gamma irradiation in water, with low doses of 5, 10, 15, 20, 25, and 30 kGy. To better distinguish the changes the radiation caused in the GTR and the surface activation of the GTR caused by the irradiated water, we also performed radiation treatments in an inert atmosphere. We mixed the treated GTRs with fresh rubber, and after vulcanization, investigated the mechanical properties and conducted dose optimization. The chemical changes occurring in GTR were characterized by Soxhlet-extraction and cross-link density measurements. Changes on the surface were investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). In water irradiation, cross-link density decreased (∼10 %), while in an inert atmosphere, new bonds formed between the chains (∼10 %), with negligible degradation (∼2 %) in both cases. Based on the FTIR spectra, new oxygen-containing groups appeared on the GTR surface in water treatment, while this was not observed in a nitrogen atmosphere. The increase in surface oxygen content was confirmed by XPS, showing a ∼10 % increase as a result of water treatment, while it remained unchanged in the inert atmosphere. We achieved a 30 % increase in tensile strength (5 kGy) without a decrease in elongation properties and a 32 % increase in tear strength (20 kGy) for vulcanizates containing surface-activated GTR. Mechanical properties did not improve with treatments in an inert atmosphere. The oxidizing agents formed during the radiolysis of water activated the surface of the GTR, helping to establish a better connection with the matrix.

High-throughput methods are extremely important in today’s materials science, especially in the case of thin film characterization. The micro-combinatorial method enables the deposition and characterization of entire multicomponent thin film systems within a single sample. In this paper, we report the application of this method for the comprehensive TEM characterization of the Y-Ti-O layer system. Variable composition samples (Y_xTi_1−xO_y) were prepared by dual DC magnetron sputtering, covering the entire (0 ≤ x ≤ 1) concentration range. The structure and morphology of phases formed in both as-deposited and annealed samples at 600, 700, and 800 °C were revealed as a function of Y-Ti composition (x). A comprehensive map showing the appropriate amorphous and crystalline phases, and their occurrence regions of the whole Y-Ti-O layer system, was revealed. Thanks to the applied method, it was shown with ease that at the given experimental conditions, the Y₂Ti₂O₇ phase with a pyrochlore structure forms already at 700 °C without the TiO₂ and Y₂O₃ by-phases, which is remarkably lower than the required temperature for most physical preparation methods, demonstrating the importance and benefits of creating phase maps in materials science and technology.