Showing papers on "Photocatalysis published in 1981"
TL;DR: The photoelectrochemistry at semiconductor electrodes has been used to design systems for heterogeneous photosynthesis1,7 and photocatalysis8,9,10 as mentioned in this paper, however, no attempt at the organic synthesis of highly valuable compounds from cheap raw material except for a very low yield of amino acids produced from methane-ammonia-water.
Abstract: The photoelectrochemistry at semiconductor electrodes has been used to design systems for heterogeneous photosynthesis1–7 and photocatalysis8–10. There has been, however, no attempt at the organic synthesis of highly valuable compounds from cheap raw material except for a very low yield of amino acids11 produced from methane–ammonia–water. If such products were to be formed in one step by heterogeneous photocatalytic reactions, this would be a highly efficient means for the economical utilization of solar energy in comparison with hydrogen production, even though the reactions are driven in a spontaneous (ΔG°<0) direction by the light energy.
424 citations
TL;DR: In this article, a bifunctional redox catalyst composed of RuO2 and Pt co-supported on colloidal TiO2 particles is used for water decomposition by visible light illumination.
Abstract: A bifunctional redox catalyst, composed of Pt and RuO2 co-deposited on a colloidal TiO2 carrier, is a highly potent mediator for water decomposition by visible light1. The system contains apart from the sensitizer (Ru(bipy)2+3) an electron relay—methylviologen. The latter is reduced on light excitation, and the photoreaction is coupled with catalytic steps2 generating H2 and O2 from water. To rationalize the surprisingly high efficiency of this photoredox system, we proposed a mechanism involving species adsorbed at the TiO2 surface. This led us to explore sensitizers which through suitable functionalization show an enhanced affinity for adsorption at the particle–water interface. We describe here the performance of electron relay-free systems capable of efficiently decomposing water into H2 and O2 under visible light illumination. A bifunctional redox catalyst composed of RuO2 and Pt co-supported on colloidal TiO2 particles is used. The only other component present is a sensitizer. Amphiphilic surfactant derivatives of Ru(bipy)2+3 exhibit extremely high activity in promoting the water cleavage process. Adsorption of the sensitizer at the TiO2 particle–water interface and electron ejection into the TiO2 conduction band are evoked to explain the observations. Exposure to UV radiation leads to efficient water cleavage in the absence of sensitizer.
353 citations
TL;DR: The quantum yield of hydrogen production was increased greatly by supporting metals or metal complexes on the TiO2 surface, amounting to 38% for a Pt-TiO2 photocatalyst.
218 citations
TL;DR: The photocatalytic decomposition of gaseous water takes place over platinized TiO2 coated with NaOH (more than 7 wt) as mentioned in this paper and the quantum efficiency of H2 and O2 production reaches about 7% (20 μmole H2/hr) at the beginning of the reaction but declines with accumulation of the products due to the thermal back reaction over Pt.
127 citations
TL;DR: In this paper, it was shown that MnO 2 is the catalyst of oxygen evolution at the oxidation of water by the one-electron oxidant Ru(bpy) 3 3+ in neutral and slightly acidic media.
59 citations
TL;DR: In this article, the photocatalytic properties of amorphous titania in the form of a porous glass were investigated and an inexpensive method of forming monolithic porous titania glass (PTG) was reported.
Abstract: The rutile modification of TiO2 in the form of a powder suspended in water shows promise as a photocatalyst for the production of hydrogen from water1,2. Although hydrogen production was reported3 from pure rutile powder suspended in an aqueous solution, subsequent work1,2 revealed that sustained hydrogen production required Pt or RuO2 on the rutile surface. This limiting usefulness of crystalline rutile in photocatalytic applications has prompted us to investigate the photocatalytic properties of amorphous titania in the form of a porous glass. Here we report an inexpensive method of forming monolithic porous titania glass (PTG) and some properties that make it uniquely suited to photocatalytic applications such as its inexpensive fabrication, its high surface area, and its spontaneous photo-formation of H2 from water without the need for precious metals.
56 citations
TL;DR: In this paper, the effect of other semiconductor materials and Fe2+ on the reaction was investigated, and all the products expected from the Fenton reaction were obtained, including the products obtained from the reaction in the presence of illuminated TiO2 powders.
Abstract: Heterogeneous photocatalytic oxidation of aromatic compounds by H2O2 formed from dissolved O2 in the presence of illuminated TiO2 powders was investigated with reference to the Fenton reaction. All the products expected from the Fenton reaction were obtained. The effect of other semiconductor materials and Fe2+ on the reaction was also investigated.
49 citations
TL;DR: In this paper, the effect of light on the rate of H2 and CO oxidation was studied over LaCoO3, ZnO, and TiO2 in the dark and while being irradiated with band-gap light.
40 citations
TL;DR: In this paper, a cyclopentane-deuterium isotopic exchange (CDIE) was performed at −10 °C with a C5H10D2 ratio of ∼-6.4% over an illuminated (300-410 nm) 0.5 wt% Pt/anatase catalyst.
39 citations
TL;DR: In this paper, interface charge transfer processes between dye redox systems and semiconductor TiO 2 powder in the anatase form were reported, and their relationship to H 2 evolution, experimental temperature, photon flux and relay concentration in ihe photocatalysis were studied.
20 citations
TL;DR: In this article, the process of hydrogen liberation and the properties of the catalysts used have been studied, and the results showed that hydrogen can be produced by visible light irradiation of neutral aqueous solutions, containing acridine yellow dye as a sensitizer, methyl viologen, an electron donor and several new catalysts.
Abstract: Hydrogen is produced catalytically by visible light irradiation of neutral aqueous solutions, containing acridine yellow dye as a sensitizer, methyl viologen, an electron donor (EDTA) and several new catalysts. The process of hydrogen liberation and the properties of the catalysts used have been studied.
TL;DR: In this article, the mechanism of photo-catalytic oxidations was investigated and showed that NO decomposes, producing N 2 and N 2 O. In the presence of an alcohol, such as a butanol, the decomposition is increased and the corresponding aldehyde or ketone is formed.
Abstract: Over UV irradiated anatase NO decomposes, producing N 2 and N 2 O. In the presence of an alcohol, such as a butanol, the decomposition is increased and the corresponding aldehyde or ketone is formed. Besides the possibility of using NO as an alternative oxidant, this brings information on the mechanism of photo-catalytic oxidations.
TL;DR: The cupric ions are photo-catalytically active already at trace concentrations (10-7), i.e., at the concentrations present in any real reaction system as discussed by the authors.
Abstract: Quantum yields of hydrogen peroxide photolysis increase with the square root of concentration of added Cu(II). The cupric ions are photo-catalytically active already at trace concentrations (10-7), i.e., at the concentrations present in any real reaction system. Hydrogen peroxide photolysis is completely suppressed on addition of complexing agents such as EDTA. It is believed that no hydrogen peroxide photolysis would occur in complete absence of photo-catalytically active transition metal ions
01 Sep 1981
TL;DR: In this article, the photocatalytic and photoelectrochemical properties of SrTi03 surfaces were studied in several different gas and liquid-phase environments, and it was shown that the photoactivity increased rapidly at alkaline hydroxide concentrations above SM.
Abstract: aThe photocatalytic and photoelectrochemical · properties of SrTi03 surfaces were studied in several different gas and liquid-phase environments. Platinized SrTi03 crystals catalyzed the dissociation of water to hydrogen and oxygen when illuminated with bandgap radiation in aqueous alkaline electrolytes or in water vapor when covered by films of basic deliquescent compounds. The rate of photodissociation increased rapidly at alkali hydroxide concentrations above SM. No photoactivity was seen in neutral or a'cidic solutions, nor in water vapor at 300°K in the absence of basic films. Platinum-free SrTi03 was also active for hydrogen photogeneration. All chemistry occured on the illuminated surface of the semiconductor. Photoactivity on metal-free surfaces also increased at higher hydroxide concentrations. The mechanisms by which both surface and electrolyte hydroxide species can promote photocatalysis at the gas-solid interface were explored. The differences between the catalysis of water