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Synthetic opals, a composition of homogeneous silica spheres in the mesoscale size range, have attracted the attention of scientists due to their favorable chemical and physical properties. Their chemical inertness and stability, biocompatibility, homogeneity, elevated specific surface area, and ease of functionalization of their surfaces make them a versatile nanotool. In the present study, the Stöber process was used to investigate the effect of parameters, such as reagent concentration and synthesis temperature, on the resulting silica particle size and structure. The optimal conditions for successfully obtaining homogeneous particles in the mesoscale range with high reproducibility were investigated. Several synthesis procedures and their dependence on the reaction temperature were presented to allow the selection of the assumed diameter of silica spheres. The numerous samples obtained were examined for size, homogeneity, structure, and specific surface area. On the basis of specific surface area measurements and nuclear magnetic resonance studies, the internal hierarchical structure of the spherical silica was confirmed as consisting of a solid core and layers of secondary spheres covered by a solid shell. Structural studies (X-ray Spectroscopy, X-ray Absorption Near-Edge Structure, and nuclear magnetic resonance), together with infrared vibrational spectroscopy, showed no dependence of the structure of the obtained mesospheres on the concentration of reagents and the size of the obtained particles. [ABSTRACT FROM AUTHOR]

Alternative Local Melting-Solidification of Suspended Nanoparticles for Heterostructure Formation Enabled by Pulsed Laser Irradiation (Adv. Funct. Ab-initio calculations, heterostructures, laser-suspension interactions, phase formation, reactive bond molecular dynamics The synthesized submicron Cu-CuO-Cu SB 2 sb O heterostructures containing Cu SB 2 sb O SB 3 sb phase are thoroughly investigated for application in ethanol oxidation fuel cells. [Extracted from the article]

[Display omitted] • Atomically dispersed Cu on TiO2 nanoparticles synthesized by the wet impregnation method; • 100% Selectivity to hydrogen in the methanol photoreforming has been achieved; • Cu2+ Oxidation state bypassed to prevent CO 2 generation; • Cu+→Cu0 → Cu+ Redox cycle identified under the reaction conditions; • An apparent quantum efficiency of 10% at λ = 365 nm and the 0.45 W LED source. Hydrogen generation by photoreforming of methanol is being one of the most intensely investigated photochemical transformations in pursuing a sustainable, zero waste circular economy. This transformation usually produces a significant amount of gaseous carbon in the form of CO 2 and CO that disqualifies many active photocatalysts as being fully sustainable. Here, we demonstrate the atomically dispersed Cu on TiO 2 composite nanoparticles synthesized by the wet impregnation method that are highly active and selective in hydrogen production by photoreforming of methanol solution. Our photocatalyst exhibits an apparent quantum efficiency of 10% at 365 nm wavelength and the low power 0.45 W light emitting diode (LED) source. The only gaseous product found is molecular hydrogen, whereas all carbon is trapped in the downstream liquid mixture of formaldehyde and formic acid, making the process fully sustainable and clean. We used various experimental techniques and density functional theory calculations (DFT) to characterize our photocatalysts and provide an insight into the exceptional behavior of the Cu/TiO 2 system. A combination of ab initio DFT and X–ray photoelectron spectroscopy (XPS) measurements allowed us to identify the Cu+–Cu0–Cu+ redox cycle under the reaction conditions. Bypassing the Cu2+ oxidation state is crucial to keep the oxidation potential of photogenerated holes low enough to prevent CO 2 generation and keeping all carbon in the liquid phase. This work paves the way toward an efficient and clean generation of hydrogen by photoreforming of methanol over well–established and cheap Cu/TiO 2 photocatalyst. [ABSTRACT FROM AUTHOR]