Showing papers on "Photocatalysis published in 1970"

Copper/reduced graphene oxide nanocomposite for high performance photocatalytic methylene blue dye degradation

Abstract: Copper nanoparticles deposited on reduced graphene oxide (RGO) have been investigated for various applications. In many of these reports RGO is used as a support and electron collector and not as a light absorber. However, Cu nanoparticle decorated over the surface of semiconducting RGO as a light absorber has not been investigated for its photocatalytic organic dye degradation activity. Here, we deposited Cu nanoparticle on RGO sheet by insitu photoreduction method. The Cu/RGO nanocomposite photocatalyst material is characterized by UV-Visible spectroscopy, FT-IR and X-ray powder diffraction and its photodegradation activity towards model organic dye was investigated. Based on our results, it was found that the photocatalytic degradation efficiency of GO, RGO and Cu/RGO nanocomposites were 63%, 68% and 94%, respectively under light irradiation at pH~7 in 50 min. The high photocatalytic performance of Cu/RGO nanocomposite is due to the catalytic effect of Cu. The Cu nanoparticle is a good photoelectron acceptor that traps the photoelectron and reduces the recombination rate of photoelectron-hole pairs. We believe that our finding would be widely applicable to the graphene oxide based composites with metal or metal oxide nanoparticles to develop a cost effective technique for environmental protection.

Process for the photocatalytic oxidation of hydrocarbons into aldehydes and ketones

Abstract: Process for the oxidation of gaseous hydrocarbons or hydrocarbons in the gaseous or vapour state, in heterogeneous phase, which comprises producing, at a temperature below 100*C, a circulation or continuous flow of a gaseous mixture or of gas and vapours containing the hydrocarbon to be oxidised and oxygen into contact with a catalyst subjected to ultra-violet radiation, this catalyst being constituted by a metal oxide containing or retaining by adsorption molecules of oxygen which are mobile under irradiation, such as titanium dioxide, the ultra-violet radiation being at least partly within the domain of wavelengths lower than the wave length of the radiation whose energy is that of the prohibited bandwidth of the oxide.

Homogeneous photocatalysis by organic dyes in the liquid phase.

Abstract: EXPERIMENTS using organic semiconductors as catalysts are interesting for several reasons. Organic semiconductors have a molecular lattice and the parameters of the catalyst can therefore be altered by altering the molecules forming the lattice. Organic chemistry techniques also enable single molecules to be synthesized in a tailor made fashion.

Oxidation Of Aqueous Organic Pollutants In Industrial Waste Water By Heterogeneous Photocatalysis Using A Cocurrent Downflow Bubble Column Contactor (CDC)

Abstract: The heterogeneous photocatalytic oxidation of aqueous organic pollutants to innocuous products (i.e. CO], t O) has been studied in a novel pilot scale photocatalytic reactor. Phenol was used as a representative organic pollutant and TiO] %s a photocatalyst in aqueous dispersions under UV irradiation. Complete degradation of phenol (100 %) was achieved in about 190 min of irradiation for an initial organic substrate loading of 100 mg/drrP and 18 drrP solution. The reaction was strongly pH dependent with pH 2.5-3.0 producing the maximum reaction rates. Results also indicated that complete mineralization of substrate and intermediates could not be accomplished without the addition of small quantities of f O] A Langmuir-Hinshelwood type rate expression and a pseudo 1st-order equation were used to model the reaction rate and kinetics. The experiments exemplified the suitability of the CDC photocatalytic reactor as an alternative device to degrade aqueous organic pollutants.

Dearomative Photocatalytic Construction of Bridged 1,3-Diazepanes

Abstract: The construction of diverse sp3-rich skeletal ring systems is of importance to drug discovery programmes and natural product synthesis. Herein, we report the photocatalytic construction of 2,7-diazabicyclo[3.2.1]octanes (bridged 1,3-diazepanes) via a reductive diversion of the Minisci reaction. The fused tricyclic product is proposed to form via radical addition to the C4 position of 4-substituted quinoline substrates, with subsequent Hantzsch ester-promoted reduction to a dihydropyridine intermediate which undergoes in situ two-electron ring closure to form the bridged diazepane architecture. A wide scope of N-arylimine and quinoline derivatives was demonstrated and good efficiency was observed in the construction of sterically congested all-carbon quaternary centers. Computational and experimental mechanistic studies provide insights into the reaction mechanism and observed regioselectivity/diastereoselectivity.