RESUMEN
CO emission is a critical issue of industrial processes such as steel-smelting, cement manufacturing, and waste incineration. Catalytic oxidation based on Cu-Mn binary catalysts shows great potential for efficient removal of CO, whereas their practical applicability is limited by the inferior low-temperature catalytic activity and the high catalyst cost owing to a substantial quantity of Cu. In this study, doping graphene is designed to adjust the electron transfer capability to improve the low-temperature catalytic activity as well as reduce the amount of Cu, and thereby Cu1Mn10 catalysts doped with slight amounts of graphene (x%G-Cu1Mn10, x is 1â¼5) were fabricated. It was found that the introduction of graphene could form effective electron transport channels to enhance the intermetallic interaction and oxygen vacancy generation, thus improving the low-temperature catalytic performance of the Cu1Mn10 catalyst. Among all the catalysts, 4%G-Cu1Mn10 exhibited the highest activity, achieving CO conversion of 92% at 110 °C at a weight hourly space velocity of 120,000 mL/(gâh). The introduction of graphene also enabled the catalyst with excellent catalytic activity and stability at a relative humidity of 70%. Attractively, 4%G-Cu1Mn10 can be further loaded into the polyester fabric, presenting great application potentials in the effective elimination of CO during the dust removal process since the flue gas temperature in the dust collector is just around the T90% and the catalyst that is inside of fabric fiber rather than on the fabric surface can be rarely influenced by the dust. In general, doping graphene provides a facile method to enhance the low-temperature activities of the Cu-Mn binary catalysts and cut down the use of valuable Cu, showing great application potential.
RESUMEN
An unprecedented enantioselective synthesis of spiro-γ-lactams via a sequential C-H olefination/asymmetric [4+1] spirocyclization under a simple CoII /chiral spiro phosphoric acid (SPA) binary system is reported. A range of biologically important spiro-γ-lactams are obtained with high levels of enantioselectivity (up to 98 % ee). The concise, asymmetric synthesis of an aldose reductase inhibitor was successfully achieved. Notably, contrast to previous reports that relied on the use of cyclopentadienyl or its derivatives (achiral Cp*, CptBu , or chiral Cpx ) ligated CoIII complexes requiring tedious steps to prepare, cheap and commercially available cobalt(II) acetate tetrahydrate was used as an efficient precatalyst.
RESUMEN
W atoms/clusters are employed to in situ assist the development of layered vertically aligned carbon nanotube arrays (VACNTs) through hot-filament-assisted chemical vapor deposition (HFCVD) with liquid binary Fe3O4/AlOx catalysts. The hot W filament was utilized to in situ evaporate atomic W and form W clusters on Fe catalysts, which have a strong impact on the growth of layered VACNT arrays. The migration and Ostwald ripening of Fe catalysts are found to be suppressed immediately with more W clusters deposition during CNT growth. Through controlling the deposition of W clusters, the electrochemical energy storage performance of as-prepared layered VACNT arrays is also tunable as electrodes of ion-based supercapacitors. The layered VACNT arrays can achieve a high capacity of 83.1 mF cm-2 and possess desirable rate performance due to the suitable hot filament condition (55 W for 90 s). This work provides a new perspective to in-depth understand the behavior of W filament during HFCVD and the significant role of the in situ generated W clusters on the growth of CNTs by maintaining the catalytic activity and structure of catalysts.
RESUMEN
Cu-In metallic hybrid is a promising non-noble catalyst for selective electrochemical CO2 reduction (eCO2R) to CO, but the lack of direct assembly with a gas diffusion electrode (GDE) limits the further development of eCO2R to CO with both high Faradaic efficiency (FE) and high current density. In this study, an in situ electrochemical spontaneous precipitation (ESP) method was applied for the first time to prepare GDE-combined Cu-In electrocatalysts. The optimum Cu-In catalyst consists of a nanoscale "core-shell" structure of polycrystalline CuxO covered by the amorphous In(OH)3 interface. Higher than 90% FE of CO production has been achieved. With the synergy of a GDE flow cell and 1 M KOH catholyte, a current density of â¼200 mA cm-2 was reached at -1.17 V (reversible hydrogen electrode), which enabled a CO yield efficiency record of 3.05 mg min-1(CO2/15 mL min-1 with a 2 cm2 electrode). The ratios between CO and H2 produced can be effectively modulated via fine-tuning ESP conditions demonstrating possibility of generating CO or syngas with tuneable ratios. The present study provides a simple approach for constructing novel catalytic interfaces with dual active centers for eCO2R and other emerging electrochemical catalysis research.