Photocatalysis

About: Photocatalysis is a research topic. Over the lifetime, 67088 publications have been published within this topic receiving 2145233 citations. The topic is also known as: photocatalyst.

Photocatalytic Water Oxidation on BiVO4 with the Electrocatalyst as an Oxidation Cocatalyst: Essential Relations between Electrocatalyst and Photocatalyst

Abstract: The oxygen evolution is kinetically the key step in the photocatalytic water splitting. Cocatalysts could lower the activation potential for O2 evolution. However, the cocatalyst for O2 evolution has been less investigated, and few effective cocatalysts were reported. This paper reports that the O2 evolution rate of photocatalytic water splitting under visible light irradiation can be significantly enhanced when the electrocatalyst cobalt–phosphate (denoted as CoPi) was deposited on BiVO4. The photocurrent density is also greatly enhanced by loading CoPi on BiVO4 electrode, and this enhancement in performance shows the similar trend between the photocatalytic activity and photocurrent density. We also found that this tendency is true for BiVO4 loaded with a series of different electrocatalysts as the cocatalysts. These results demonstrate that an effective electrocatalyst of water oxidation can be also an effective cocatalyst for O2 evolution from photocatalytic water oxidation. By depositing the CoPi as ...

Sonochemical synthesis of nanocrystallite Bi2O3 as a visible-light-driven photocatalyst

Abstract: The synthesis of Bi2O3 by a simple sonochemical route is investigated. Surfactant polyvinylpyrrolidone (PVP) has strong effects on the grain sizes and morphologies of Bi2O3. Bi2O3 single crystallite with grain size of 40–100 nm is obtained in the presence of 0.5 g PVP. X-ray diffraction (XRD) pattern shows that the nanocrystallite Bi2O3 is monoclinic and has a high degree of crystallinity. Optical characterizations show that the nanocrystallite Bi2O3 presents the photoabsorption properties from UV light region to visible light shorter than 470 nm and the band gap of the nanocrystallite Bi2O3 is 2.85 eV. The photocatalytic performance of the nanocrystallite Bi2O3 is evaluated using methyl orange (MeO) as a model pollutant. The photocatalytic results show that such nanocrystallite Bi2O3 can effectively degrade 86% MeO within 100 min under visible light illumination (λ > 400 nm). The action spectrum of MeO degradation over nanocrystallite Bi2O3 further confirms that the photocatalytic reaction can be driven by visible light. The photocatalytic mechanism is also studied based on electronic structure calculations using density functional theory (DFT).

Change of adsorption modes of dyes on fluorinated TiO2 and its effect on photocatalytic degradation of dyes under visible irradiation.

Abstract: Surface-fluorinated TiO2 (F-TiO2) particles were prepared via the HF etching method. The surface characteristics of fluorinated TiO2, the adsorption modes of dyes, and the reaction pathways for the photocatalytic degradation of dye pollutants under visible light irradiation were investigated. It was found that, in the treatment of TiO2 by HF etching, F− not only displaces surface HO− but also substitutes some surface lattice oxygen. Using zwitterionic Rhodamine B (RhB) dye as a model, the change of the adsorption mode of RhB on F-TiO2 relative to that on pure TiO2 was validated by adsorption isotherms, X-ray photoelectron spectroscopy (XPS), and IR techniques for the first time. RhB preferentially anchors on pure TiO2 through the carboxylic (−COOH) group, while its adsorption group is switched to the cationic moiety (−NEt2 group) on F-TiO2. Both the photocatalytic degradation kinetics and mechanisms were drastically changed after surface fluorination. Dyes with positively charged nitrogen-alkyl groups suc...

Photochemical cleavage of water by photocatalysis

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.