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Ruthenium was highly dispersed on graphene aerogel (GA) at high loadings to achieve high performance in COx-free hydrogen production from ammonia. Catalytic performance measurements on ammonia decomposition showed that the GA-supported catalyst with a Ru loading of 13.6 wt% provides an ammonia conversion of 71.5 % at a space-velocity of 30,000 ml NH3 g(cat)(-1)h(-1) and at 450 degrees C, corresponding to a hydrogen production rate of 21.9 mmol H-2 g(cat)(-1)min(-1). The addition of K increased the ammonia conversion to a record high value of 97.6 % under identical conditions, reaching a hydrogen generation rate of 30.0 mmol H-2 g(cat)(-1) min(-1), demonstrated to be stable for at least 80 h. A comparison of the turnover frequencies of catalysts indicated that this increase in performance upon the addition of K originated from an increase in the number of the active Ru sites and the corresponding electron density available for reaction.

In the present research, a non-equimolar Ti1.5ZrTa0.5Nb0.5Hf0.5 RHEA film with a thickness of 1.025 mu m was deposited on 316L, CoCrMo, and Ti6Al4V substrates by RF magnetron sputtering system. The micro structural characterizations showed that an amorphous and compact film with a continuous and cauliflower-like morphology was developed on the substrates. The hardness and elastic modulus of the deposited film, together with its adhesion, were determined by the nanoindentation. The RHEA-coated specimens exhibited much improved surface mechanical properties as compared with uncoated ones. The results of the scratch test demonstrated that the RHEA film provides high adhesion strength on the Ti6Al4V substrate compared to 316L and CoCrMo. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were carried out in phosphate buffer saline (BPS) solution at 37 +/- 1 degrees C. In contrast to RHEA-coated 316L and CoCrMo specimens, RHEA-Ti6Al4V showed remarkable polarization resistance without any trace of pitting on its surface. According to the EIS measurement, the charge transfer resistance of the RHEA-Ti6Al4V specimen is significantly high, about 1.5 x 10(7) Omega cm(2), owing to the strong bonding between the RHEA film and Ti6Al4V substrate. (C) 2021 Elsevier B.V. All rights reserved.

The upconversion behavior of Er3+/Tm3+ co-doped Ruddlesden-Popper type K(2)Ln(2)Ti(3)O(10) layered perovskites was investigated. The lanthanide pair was selected for achieving 980 nm-driven green, red, and NIR emission. The perovskites having different dopant compositions were synthesized by a conventional solid-state procedure by substitution of La3+ ions in the host lattice. Moreover, the single nanosheets having approximately 1.8 nm thickness and 2 mu m lateral size were obtained via chemical exfoliation. The non-doped and co-doped layered materials and the nanosheets derived from these materials were characterized by X-ray diffraction, Scanning Electron Microscopy, Atomic Force Microscopy and custom-made experimental set-up of upconversion emission spectroscopy. According to the XRD profiles, the perovskites had the layered orientation and water molecules in the interlayer domain because of their hygroscopic nature. The co-doped layered perovskites presented twophoton excited green and red emissions, identified as S-4(3/2) -> (4)I(15/2 )with H-2(11/2) -> (4)I(15/2 )and F-4(9/2) -> I-4(15/2) of the Er3+ transitions with a NIR emission. The intensity of red to green ratio emission of the materials increased with respect to the co-dopant concentration. The nanosheets' upconversion emission was weak in the visible region compared to their layered morphology. On the other hand, the NIR emission based on H-3(4) -> H-3(6) transition of the Tm3+ ions was preserved despite the acid and solvent treatments to break apart the layered orientation. MTT assay and Calcein/PI staining were conducted to evaluate cytotoxicity of non-doped and Er3+/Tm3+ co-doped K(2)Ln(2)Ti(3)O(10) perovskites and their exfoliated nanosheets on HEK 293 and HepG2 cell lines. Both assays indicated that although cell viability decreases with increasing concentration, good cell viability was observed at even 100 mu g/mL. In addition to their excellent luminescent and optical features, the nanomaterials also demonstrated low cytotoxicity increasing the potential for their use in laser-based biological applications.

Er3+ doped BST nanoparticles with Aurivillius layered structure are synthesized through common solid-state method. Photoluminescence spectroscopy has shown that these oxides are capable of emitting light under UV (366 nm) and IR (980 nm) source. The effect of Er3+ to Yb3+ concentration ratio on upconversion emission are investigated and possible upconversion and energy transfer mechanisms are suggested based on the number of photons participating in UC process. Shift in the upconversion emission from green to red region is visualized by CIE chromaticity diagram. The superiority of coexistence of stoke and anti-stoke emission in a single host lattice with a single activator ion, besides to tunability of UC luminescence only by controlling sensitizer/activator ratio are very interesting features which can be used to produce dual mode multicolor luminescent ink with high security level against forgery.

Residual stress gradients in electroplated nickel films of 1 mu m thickness are characterized for a wide range of current densities (1-20 mA/cm(2)) and electroplating temperatures (30-60 degrees C) in a nickel sulfamate bath. Although a variety of stress measurements is available, exploration of stress gradients remain unstudied at the scale of 1 mu m. Stress gradients - unlike uniform stresses - can cause significant bending even in monolayered released structures. Moreover, examples of misinterpretation of wafer curvature data as a measure of stress gradients exist in the literature. Based on these motivations, monolayered Ni microcantilevers are employed in this work as mechanical transducers for the characterization of stress gradients within the nickel film. Experiments are supported with finite element simulations. Residual stress gradient is found to vary in the range of about 130 to 70 MP/mu m with the sign change indicating a transition from downward to upward deflection of the microcantilever. Thus, a window of electroplating parameters is established yielding zero residual stress gradients, i.e. straight cantilevers, without the use of any additive agents. (C) 2015 Elsevier B.V. All rights reserved.

Carbon aerogel (CA) supported Pt-Cu bimetallic nanoparticles were synthesized via simultaneous adsorption of bis(1,1,1,3,5,5,6,6,6-nonafluorohexane-2,4-diiminate)copper (CuDI6) and dimethyl(1,5-cyclooctadiene)platinum(II) (Pt-(cod)me(2)) onto CM in the presence of supercritical carbon dioxide (scCO(2)) and subsequent thermal conversion at ambient pressure. Binary adsorption isotherms of metal precursors on CM in scCO(2) were measured at 35 degrees C and 10.6 MPa by analyzing the fluid phase concentrations in a batch system and could be predicted from pure component adsorption isotherms using ideal adsorbed solution theory (IAST). Homogeneously dispersed Pt-Cu nanoparticles were formed on the surface of the CM via the thermal conversion of the precursors at 400 degrees C. As the Pt/Cu ratio decreased from 97:3 to 21:79, both the mean and the standard deviation of the particle size increased from 2.9 to 7.2 nm and from 1.3 to 3.7 nm, respectively. The alloying of Pt and Cu within the nanoparticles was confirmed via XRD peak shifts, and XPS data indicated that the surfaces of these Pt-Cu alloy nanoparticles were enriched in Pt.