We have investigated the effect of H2O2 on behavior O2•- and OH• produced in photocatalysis aqueous TiO2 suspensions by means luminol chemiluminescence probing terephthalic acid fluorescence probing, respectively. The reduction O2 photoinduced conduction band electrons (e-) was increased addition H2O2, since consumption valence holes (h+) oxidation caused repression e-−h+ recombination. After end light irradiation, amount decreased based fractal-like kinetics at heterogeneous surface...

ADVERTISEMENT RETURN TO ISSUEPREVViewpointNEXTUnderstanding Hydroxyl Radical (•OH) Generation Processes in PhotocatalysisYoshio Nosaka* and Atsuko NosakaView Author Information Department of Materials Science Technology, Nagaoka University 940-2188, Japan*E-mail: [email protected]Cite this: ACS Energy Lett. 2016, 1, 2, 356–359Publication Date (Web):July 7, 2016Publication History Received27 May 2016Accepted30 June 2016Published online7 July inissue 12 August...

The difference in the OH radical generation through photocatalytic reaction with distinct crystalline types of TiO2 aqueous suspension was explored by means a fluorescence probe method. By employing two kinds molecules different adsorptivities, that is, coumarin and coumarin-3-carboxylic acid, we could detect radicals located near surface those bulk solution individually. amount much larger than solution, which diffused from to solution. Rutile produced smaller as compared anatase...

Amorphous copper oxide (Cu(II)) nanoclusters function as efficient electrocatalysts for the reduction of carbon dioxide (CO2) to monoxide (CO). In addition promoting electrocatalytic activity, Cu(II) act cocatalyts CO2 photoreduction when grafted onto surface a semiconductor (light harvester), such niobate (Nb3O8–) nanosheets. Here, photocatalytic activity and reaction pathway Cu(II)-grafted Nb3O8– nanosheets was investigated using electron spin resonance (ESR) analysis isotope-labeled...

In order to utilize visible light in photocatalytic reactions, nitrogen atoms were doped commercially available TiO2 powders by using an organic compound such as urea and guanidine. Analysis X-ray photoelectron spectroscopy (XPS) indicated that N incorporated into two different sites of the bulk phase TiO2. A significant shift absorption edge a lower energy higher region observed. These N-doped exhibited activity for decomposition 2-propanol aqueous solution under irradiation. The increased...

Photoinduced reaction with TiO2 semiconductor photocatalysts was investigated by using nitroxide radicals as spin probes for ˙OH radicals. The effects of some additives such I−, Cl−, ClO4−, methanol and 2-propanol on the photocatalytic decay radicals, 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidine-1-oxyl 4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl, were investigated. Among additives, only iodide ions that can be oxidized trapped holes prohibited significantly indicating oxidize probe For...

Singlet molecular oxygen (1O2), which was produced with a significant yield, detected from powder-type TiO2 photocatalyst irradiated 355-nm laser pulse by monitoring its near-infrared phosphorescence at 1270 nm. Lifetime measurements for the 1O2 (Degussa P25) in various environments, such as air and suspensions of H2O, D2O, ethanol, indicated that quenching takes place mainly surface absence reactants. Quantum yields generation were measured ten commercial photocatalysts ranged 0.12 to 0.38,...

The formation of reactive singlet oxygen molecule (1O2), the a1Δg state excited O2, in photocatalytic TiO2 aqueous suspension system was shown to be evident by detecting near-infrared phosphorescence at 1270 nm means a gated photon counting method. lifetimes O2(1Δg) three different media (water, ethanol, 1∶1 water–ethanol mixture) were elucidated and compared with those reported corresponding homogeneous media. Based on comparison lifetime other species such as OH radicals trapped holes,...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFinite depth spherical well model for excited states of ultrasmall semiconductor particles: an applicationYoshio NosakaCite this: J. Phys. Chem. 1991, 95, 13, 5054–5058Publication Date (Print):June 1, 1991Publication History Published online1 May 2002Published inissue 1 June 1991https://doi.org/10.1021/j100166a028RIGHTS & PERMISSIONSArticle Views760Altmetric-Citations163LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum full text...

The reaction mechanism of visible-light responsive photocatalysts was explored by analyzing OH radicals (•OH) quantitatively means a coumarin fluorescence probe method. investigated were various modified TiO2, i.e., nitrogen-doped, Pt-complex-deposited, Fe(III)-grafted, and Fe(III)-grafted Ru-doped TiO2. formation rate •OH measured to calculate the quantum yield from absorbed intensity 470 nm LED light. highest obtained for increased on addition H2O2 indicating that is supposedly...

Various kinds of TiO2 photocatalysts have been practically applied in various fields. Knowing the exact surface properties is a prerequisite to develop further and efficient applications. However, cause essential difference activities two polymorphs TiO2, rutile anatase, has not clearly elucidated yet. We tried clarify terms active oxygen species (˙OH, ˙O2(-), H2O2) photogenerated on surfaces, which are considered involved photocatalytic reactions. It was revealed that for anatase rate ˙OH...

The reaction mechanism of visible-light responsive Cu(II)-grafted TiO2 and WO3 photocatalysts was analyzed by detecting trapped holes electrons means electron spin resonance (ESR) spectroscopy O2•- H2O2 chemiluminescence photometry. At first, the photocatalytic activities were confirmed for acetaldehyde decomposition in gas phase under 470 nm light emitting diode (LED) irradiation. reduction grafted Cu2+ ions alternative O2 resultant Cu+ shown ESR measurements at 77 K both irradiation...

Titanium dioxide (TiO2), as an excellent photocatalyst, has been intensively investigated and widely used in environmental purification. However, the wide band gap of TiO2 rapid recombination photogenerated charge carriers significantly limit its overall photocatalytic efficiency. Here, efficient visible-light-active photocatalysts were developed on basis modified with two ubiquitous nanoclusters. In this system, amorphous Ti(IV) oxide nanoclusters demonstrated to act hole-trapping centers...

ADVERTISEMENT RETURN TO ISSUEPREVViewpointNEXTReconsideration of Intrinsic Band Alignments within Anatase and Rutile TiO2Yoshio Nosaka* Atsuko Y. NosakaView Author Information Department Materials Science Technology, Nagaoka University 940-2188, Japan*E-mail: [email protected]Cite this: J. Phys. Chem. Lett. 2016, 7, 3, 431–434Publication Date (Web):February 4, 2016Publication History Published online4 February 2016Published inissue 4...

We successfully clarified the mechanisms of visible-light-driven photocatalytic reactions Fe(III)-grafted TiO2 (Fe/TiO2) and Ru-doped (Fe/Ru:TiO2). ESR spectroscopy revealed that visible-light response Fe/TiO2 photocatalyst resulted in direct charge transfer from valence band to grafted Fe ions. For Fe/Ru:TiO2 photocatalyst, acceptor levels were formed by doping Ru ions lattice TiO2, electrons at excited on irradiation readily Since a longer wavelength light generated conduction electrons,...

The experimental results in photoelectrolysis with rutile (100) and (110) TiO₂ single crystals support a plausible reaction mechanism that the surface Ti–O–O–Ti structure is an intermediate of water oxidation process, by which O₂ production becomes favorable alkaline solution.

A chemiluminescent probe, luminol, was successfully applied to monitoring superoxide ions (O2•-) and hydrogen peroxide (H2O2) produced on photocatalytic reaction in aqueous TiO2 suspension. Two reactions were distinguished from the decay profile after end of irradiation, mechanism analyzed. The fast component gives information about O2•- slow one provides amount H2O2. rate constant for with luminol found be 1 × 104 M-1 s-1. during irradiation alkaline solution could estimated order 10-13 M....

Active oxygen species formed on TiO2 film photocatalysts in air were examined by use of a chemiluminescence method. Under relatively strong UV light irradiation, 15 mW cm-2, two types active the surface observed after interception excitation light, i.e., one with shorter lifetime, ca. 3 s, and another longer 50 which may correspond to superoxide (O2-). On contrary, under weak 1 μW only long-lived species, O2-, was observed. The concentration O2- saturated even illumination, while short-lived...

Superoxide ions (O2•−) and hydrogen peroxide (H2O2) produced by visible light irradiation were analyzed to investigate the photocatalytic reaction mechanism for commercially available nitrogen- sulfur-doped TiO2 (BAPW25 SJC). O2•− was detected chemiluminescence (CL) probe method with luminol, while amount of H2O2 measured as CL intensity luminol oxidized upon addition hemoglobin. By 442-nm light, S-doped surpassed N-doped in ability produce O2•−, accumulating H2O2. The difference processes...