Formation and growth characteristics of nanostructured carbon films on nascent Ag clusters during room-temperature electrochemical CO2 reduction

Synthesis of carbon nanostructures at room temperature and under atmospheric pressure is challenging but it can provide significant impact on the development of many future advanced technologies. Here, the formation and growth characteristics of nanostructured carbon films on nascent Ag clusters during room-temperature electrochemical CO(2) reduction reactions (CO(2)RR) are demonstrated. Under a ternary electrolyte system containing [BMIm](+)[BF(4)](−), propylene carbonate, and water, a mixture of sp(2)/sp(3) carbon allotropes were grown on the facets of Ag nanocrystals as building blocks. We show that (i) upon sufficient energy supplied by an electric field, (ii) the presence of negatively charged nascent Ag clusters, and (iii) as a function of how far the C–C coupling reaction of CO(2)RR (10–390 min) has advanced, the growth of nanostructured carbon can be divided into three stages: Stage 1: sp(3)-rich carbon and diamond seed formation; stage 2: diamond growth and diamond–graphite transformation; and stage 3: amorphous carbon formation. The conversion of CO(2) and high selectivity for the solid carbon products (>95%) were maintained during the full CO(2)RR reaction length of 390 min. The results enable further design of the room-temperature production of nanostructured carbon allotropes and/or the corresponding metal-composites by a viable negative CO(2) emission technology

Antimicrobial properties dependence on the composition and architecture of copper-alumina coatings prepared by plasma electrolytic oxidation (PEO)

This study presents environmentally friendly and low-cost synthetic routes to produce antimicrobial coatings over 5052 Al alloy based on plasma electrolytic oxidation (PEO) technology. Two methodologies were explored: the decoration with copper and anodic doping with copper ions. The porous oxide layers produced in silicate media presented two porous layers consisting of γ-Al2O3 crystalline phase and amorphous phases of aluminosilicate, silica, and Al(OH)3. Small amounts of copper (&lt;0.3 at.%) were detected in the PEO films. In the Cu-decorated film, copper clusters composed of Cu0 and Cu2+ species were observed visually as small black dots on the surface. In the Cu-doped film, the Cu2+ and Cu+ species were homogeneously distributed on the surface. The copper content affected the corrosion performance in aggressive corrosive media. The PEO coatings showed a remarkable antimicrobial activity after 24 h in standard tests. The antimicrobial effectiveness of the Cu-decorated sample was higher against S. aureus, while the Cu-doped sample was more effective against E. coli. The results demonstrated that differences in the PEO coating architecture can affect the material composition and, consequently, the bacterial inactivation mechanism. These findings can serve as a guide to tailor aluminum alloys for specific antimicrobial surfaces.</p

Catalytic Activity During Copolymerization of Ethylene and 1-Hexene via Mixed TiO2/SiO2-Supported MAO with rac-Et[Ind]2ZrCl2 Metallocene Catalyst

Activities during ethylene/1-hexene copolymerization were found to increaseusing the mixed titania/silica-supported MAO with rac-Et[Ind]2ZrCl2 metallocenecatalyst. Energy Dispersive X-ray spectorcopy (EDX) indicated that the titania wasapparently located on the outer surface of silica and acted as a spacer to anchor MAO tothe silica surface. IR spectra revealed the Si-O-Ti stretching at 980 cm-1 with low contentof titania. The presence of anchored titania resulted in less steric hindrance and lessinteraction due to supporting effect

Simple, controllable and environmentally friendly synthesis of FeCoNiCuZn-based high-entropy alloy (HEA) catalysts, and their surface dynamics during nitrobenzene hydrogenation

High-entropy alloys (HEAs) have rapidly become one of the hottest research topics in several fields, including materials science, corrosion technology, and catalysis because of their multiple advantages and their potential applications. In this study, using a novel straightforward electroless deposition method, multi-elemental alloys (FeCoNiCuZn) supported on graphite were prepared with controlled metal loading (HEA/g-X; X = 40, 80, 100) without any high temperature post-treatments. These materials were characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, and showed a composition ranging from 11 at.% to 31 at.% for each metallic element, a total metal loading varying from 1.3 to 5.2 at.% (5.9 to 21.5 wt.%), homogeneous distribution, and an amorphous structure. Electrochemical impedance spectroscopy, cyclic voltammetry, linear sweep voltammetry, and chronoamperometry were used to evaluate the surface dynamics and the effect of the solution pH during the electrochemical hydrogenation of nitrobenzene using the HEA/g-40 material. The nitrobenzene conversion (&gt;9 mmolNB gcat-1 h−1) and aniline production (≈ 4 mmolAN gcat-1 h−1) rates in Na2SO4 solution (at −1.0 V vs. Ag/AgCl) demonstrated a strong dependence on the applied potential. After comparing the results in alkaline medium (KOH), a competitive adsorption of species (nitrobenzene and H2O) was observed, showing a synergistic effect that greatly improved the selectivity of the nitrobenzene hydrogenation to aniline, from 23% in Na2SO4 to an outstanding 94% in KOH at the same applied potential, surpassing the results of a platinum electrode (34% in KOH). These results provide insightful information regarding the nature of the active sites involved in each step of the reaction mechanism, and gives useful means to develop new, tailored multifunctional HEA electrocatalyst materials.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Micro and Nano Engineerin