Effective Activation of Strong C-Cl Bonds for Highly Selective Photosynthesis of Bibenzyl via Homo-Coupling

Carbon-carbon (C-C) coupling of organic halides has been successfully achieved in homogeneous catalysis, while the limitation, e.g., the dependence on rare noble metals, complexity of the metal-ligand catalylst and the poor catalyst stability and recyclability, needs to be tackled for a green process. The past few years have witnessed heterogeneous photocatalysis as a green and novel method for organic synthesis processes. However, the study on C-C coupling of chloride substrates is rare due to the extremely high bond energy of C-Cl bond (327 kJ mol-1 ). Here, we report a robust heterogeneous photocatalyst (Cu/ZnO) to drive the homo-coupling of benzyl chloride with high efficiency, which achieves an unprecedented high selectivity of bibenzyl (93 %) and yield rate of 92 % at room temperature. Moreover, this photocatalytic process has been validated for C-C coupling of 10 benzylic chlorides all with high yields. In addition, the excellent stability has been observed for 8 cycles of reactions. With detailed characterization and DFT calculation, the high selectivity is attributed to the enhanced adsorption of reactants, stabilization of intermediates (benzyl radicals) for the selective coupling by the Cu loading and the moderate oxidation ability of the ZnO support, besides the promoted charge separation and transfer by Cu species.

Nanoporous Metals: From Plasmonic Properties to Applications in Enhanced Spectroscopy and Photocatalysis

The field of plasmonics is capable of enabling interesting applications in different wavelength ranges, spanning from the ultraviolet up to the infrared. The choice of plasmonic material and how the material is nanostructured has significant implications for ultimate performance of any plasmonic device. Artificially designed nanoporous metals (NPMs) have interesting material properties including large specific surface area, distinctive optical properties, high electrical conductivity, and reduced stiffness, implying their potentials for many applications. This paper reviews the wide range of available nanoporous metals (such as Au, Ag, Cu, Al, Mg, and Pt), mainly focusing on their properties as plasmonic materials. While extensive reports on the use and characterization of NPMs exist, a detailed discussion on their connection with surface plasmons and enhanced spectroscopies as well as photocatalysis is missing. Here, we report on different metals investigated, from the most used nanoporous gold to mixed metal compounds, and discuss each of these plasmonic materials' suitability for a range of structural design and applications. Finally, we discuss the potentials and limitations of the traditional and alternative plasmonic materials for applications in enhanced spectroscopy and photocatalysis.

Fast and Efficient Piezo/Photocatalytic Removal of Methyl Orange Using SbSI Nanowires

Piezocatalysis is a novel method that can be applied for degradation of organic pollutants in wastewater. In this paper, ferroelectric nanowires of antimony sulfoiodide (SbSI) have been fabricated using a sonochemical method. Methyl orange (MO) was chosen as a typical pollutant, as it is widely used as a dye in industry. An aqueous solution of MO at a concentration of 30 mg/L containing SbSI nanowires (6 g/L) was subjected to ultrasonic vibration. High degradation efficiency of 99.5% was achieved after an extremely short period of ultrasonic irradiation (40 s). The large reaction rate constant of 0.126(8) s^-1 was determined for piezocatalytic MO decomposition. This rate constant is two orders of magnitude larger than values of reaction rate constants reported in the literature for the most efficient piezocatalysts. These promising experimental results have proved a great potential of SbSI nanowires for their application in environmental purification and renewable energy conversion.

Formation mechanism and characterization of immiscible nanoporous binary Cu–Ag alloys with excellent surface-enhanced Raman scattering performance by chemical dealloying of glassy precursors

Immiscible nanoporous binary Cu–Ag (NPCA) alloys with customizable microstructures and excellent SERS performance have been developed by dealloying metallic glasses.

Preparation of a nanoporous Cu–Ag solid solution with enhanced sono-Fenton-like catalytic activity

Uniform 3D bi-continuous nanoporous Cu–Ag solid solution (NPCS) and nanoporous copper (NPC) were successfully synthesized by dealloying Cu₇₀Y₂₈Ag₂ and Cu₇₂Y₂₈ metallic glasses, respectively, which was confirmed by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM and TEM images show that the ligament size of NPCS (d_SEM = 65 nm, d_TEM = 45 nm) is much smaller than that of NPC (d_SEM = 402 nm, d_TEM = 370 nm), which reveals that the ligaments of NPC can be significantly refined by the substitution of 2 at% Ag for Cu in the amorphous precursor. The obtained NPCS exhibits much larger specific surface area and higher total pore volume (S_BET = 8.34 m² g⁻¹, V_p = 0.093 cm³ g⁻¹) compared to NPC (S_BET = 1.77 m² g⁻¹, V_p = 0.050 cm³ g⁻¹). Furthermore, the catalytic activities of the samples were evaluated by decomposing methyl orange (MO) dye under the irradiation of ultrasound. The results show that NPCS with an extreme fine microstructure displayed superior sono-Fenton-like catalytic activity compared to NPC and commercial copper foil.

NPCS with an extreme fine microstructure displayed superior sono-Fenton-like catalytic activity compared to NPC.

Nanoporous foam fabricated by dealloying AgAl thin film through supercritical fluid corrosion

In this research, nanoporous silver foams are fabricated through dealloying Ag₃₅Al₆₅ (as atomic percentage, at%) thin films in supercritical (SC) carbon dioxide.