Concurrent Oxidation–Reduction Reactions in a Single System Using a Low-Plasma Phenomenon: Excellent Catalytic Performance and Stability in the Hydrogenation Reaction

Abstract

The catalytic activity and stability of metal nanocatalysts toward agglomeration and detachment during their preparation on a support surface are major challenges in practical applications. Herein, we report a novel, one-step, synchronized electro-oxidation−reduction "bottom-up" approach for the preparation of small and highly stable Cu nanoparticles (NPs) supported on a porous inorganic (TiO 2 @SiO 2 ) coating with significant catalytic activity and stability. This unique embedded structure restrains the sintering of CuNPs on a porous TiO 2 @SiO 2 surface at a high temperature and exhibits a high reduction ratio (100% in 60 s) and no decay in activity even after 30 cycles (>98% conversion in 3 min). This occurs in a model reaction of 4nitrophenol (4-NP) hydrogenation, far exceeding the performance of most common catalysts observed to date. More importantly, nitroarene, ketone/aldehydes, and organic dyes were reduced to the corresponding compounds with 100% conversion. Density functional theory (DFT) calculations of experimental model systems with six Cu, two Fe, and four Ag clusters anchored on the TiO 2 surface were conducted to verify the experimental observations. The experimental results and DFT calculations revealed that CuNPs not only favor the adsorption on the TiO 2 surface over those of Fe and AgNPs but also boost the adsorption energy and activity of 4-NP. This strategy has also been extended to the preparation of other single-atom catalysts (e.g., FeNPs-TiO 2 @SiO 2 and AgNPs-TiO 2 @SiO 2 ), which exhibit excellent catalytic performance.

Nature of the Poynting Vector Field Singularities in Resonant Light Scattering by Nanoparticles

“…In addition to the purely academic interest, the structure of the electromagnetic field in the immediate vicinity of a nanoparticle irradiated by a laser beam is of utmost importance for numerous nanomaterial science problems, see, e.g., [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ] and references therein. It is known that the topological structure of the Poynting vector field in resonant light scattering by nanoparticles may be complicated.…”

Adsorption of Li(I) Ions through New High-Performance Electrospun PAN/Kaolin Nanofibers: A Combined Experimental and Theoretical Calculation

“…Figure a shows XPS characterization of Li/Al-LDHs. It can be seen that Al, O, and Li elements appeared in the Li/Al-LDHs with binding energies of 73.68, 531.28, and 54.48 eV, respectively. − Figure b displays the FT-IR spectra of Li/Al-LDHs before and after the adsorption of Li­(I). Before the adsorption, the FT-IR spectra of Li/Al-LDHs exhibited Al–O stretching vibration peaks at 935, 753, and 519 cm –1 .…”

Enhanced Congo Red Adsorption and Photo-Fenton Oxidation over an Iron-Impeded Geopolymer from Ferruginous Kaolinite: Steric, Energetic, Oxidation, and Synergetic Studies

“… 10 , 11 Decontamination of CR molecules from water using innovative and low-cost techniques has been widely conducted; 10 , 11 adsorption was recommended as an effective removal technique for dissolved dyes owing to its simplicity, high efficiency, recyclability, and low cost. 12 , 13 Additionally, advanced oxidation processes, including photocatalytic and photo-Fenton oxidation, were reported as being highly effective for dye removal. 14 , 15 Such advanced oxidation techniques facilitate considerable degradation of dyes and the mineralization of dye molecules into environmental end products in the presence of sunlight or artificial light sources.…”

“…CR is widely used in the paper, cosmetics, leather, and textile industries. , However, the seepage of dissolved CR molecules into water resources induces marked toxicity and environmental effects. , The presence of CR molecules depletes dissolved oxygen in the water and its distribution during photosynthesis, thereby having a negative impact on the aquatic ecosystem . Moreover, there are several health-related side effects associated with CR pollution, including respiration problems, vomiting, carcinogenic and mutagenic effects, and diarrhea. , Decontamination of CR molecules from water using innovative and low-cost techniques has been widely conducted; , adsorption was recommended as an effective removal technique for dissolved dyes owing to its simplicity, high efficiency, recyclability, and low cost. , Additionally, advanced oxidation processes, including photocatalytic and photo-Fenton oxidation, were reported as being highly effective for dye removal. , Such advanced oxidation techniques facilitate considerable degradation of dyes and the mineralization of dye molecules into environmental end products in the presence of sunlight or artificial light sources. , Several factors control the suitability of the adsorbent and catalyst used during the oxidation processes, including recyclability, biodegradability, bandgap energy, recombination rate, thermal stability, safety, fabrication cost, and adsorption capacity …”