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XPS spectra of O 1S (A) and Ti 2p (B); a: TiO 2 (20%), b: TiO 2 (40%), c: TiO 2 (60%), d: Ag-TiO 2 -MnO x (20%), e: Ag-TiO 2 -MnO x (40%), and f: Ag-TiO 2 -MnO x (60%).
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Anatase TiO2 with different {001} and {101} facets exposing percentage are prepared, then Ag and MnOx co-loaded on those TiO2 facets through a classical photo-deposition method (denoted as Ag-TiO2-MnOx (N %), where N% means the percentage of exposed {001} facets). As-prepared samples were analyzed by scanning electron microscopy (SEM), X-ray photoe...
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... is known, light absorption greatly affects the photoactivity of a catalyst. Fig. S5 † shows the comparison of the UV-vis DRS spectra of all the samples. TiO 2 exhibited fundamental absorbance in the UV region; after dually loading TiO 2 with Ag and MnO x at different facets, the light absorption of the catalyst extended to the Vis region. Therefore, higher photoreduction rates of CO 2 were obtained for these loaded ...
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... transfer from TiO 2 to cocatalyst greatly affects the separation efficiency and then change the photoactivity of the catalyst. Only a few previous studies have been focused on the interaction of a semiconductor and a cocatalyst because it was difficult to detect. In this study, we analyzed this phenomenon via HRXPS, and the results are shown in Fig. 5. Fig. 5A shows the O 1s spectrum for three pure TiO 2 and dual-loaded TiO 2 ; a slightly negative shift (0.08 eV) was observed as the percentage of the exposed {001} facet increased from 20% to 40%; then, a significant positive shift (0.31 eV) was observed as the percentage of the exposed {001} facet increased to 60%. The Ti 2p XPS ...
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... from TiO 2 to cocatalyst greatly affects the separation efficiency and then change the photoactivity of the catalyst. Only a few previous studies have been focused on the interaction of a semiconductor and a cocatalyst because it was difficult to detect. In this study, we analyzed this phenomenon via HRXPS, and the results are shown in Fig. 5. Fig. 5A shows the O 1s spectrum for three pure TiO 2 and dual-loaded TiO 2 ; a slightly negative shift (0.08 eV) was observed as the percentage of the exposed {001} facet increased from 20% to 40%; then, a significant positive shift (0.31 eV) was observed as the percentage of the exposed {001} facet increased to 60%. The Ti 2p XPS spectrum ...
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... O 1s spectrum for three pure TiO 2 and dual-loaded TiO 2 ; a slightly negative shift (0.08 eV) was observed as the percentage of the exposed {001} facet increased from 20% to 40%; then, a significant positive shift (0.31 eV) was observed as the percentage of the exposed {001} facet increased to 60%. The Ti 2p XPS spectrum shows the same result in Fig. 5B; the binding energy of Ti 2p is 458.58, 458.5, and 458.83 eV for 20%, 40%, and 60% {001} TiO 2 , respectively. The regular shift of Ti 2p and O 1s peaks is attributed to the surface atomic configuration and coordination, which inherently determine their diverse binding energy. For instance, there are TiO 2 {101} facets with 50% ...
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... contrast to pure TiO 2 , the percentage of the {001} facets greatly affects the binding energy (BE) of Ti 2p and O1s XPS for dual-loaded TiO 2 , as shown in Fig. 5B. For the 20% samples, the peaks in Ti 2p of dual-loaded TiO 2 are almost the same as those of pure TiO 2 , implying that the electron density around Ti is unchanged. The XPS bands of O 1s of these samples are shown in Fig. 5A, Fig. S7, † and Table 1. For TiO 2 (20%), the main peaks located at 529.84 eV are attributed to the Ti-O bond ...
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... of the {001} facets greatly affects the binding energy (BE) of Ti 2p and O1s XPS for dual-loaded TiO 2 , as shown in Fig. 5B. For the 20% samples, the peaks in Ti 2p of dual-loaded TiO 2 are almost the same as those of pure TiO 2 , implying that the electron density around Ti is unchanged. The XPS bands of O 1s of these samples are shown in Fig. 5A, Fig. S7, † and Table 1. For TiO 2 (20%), the main peaks located at 529.84 eV are attributed to the Ti-O bond (lattice oxygen), and the secondary peak at 531.52 eV is attributed to the surface adsorption-OH (adsorbed oxygen). 29 Compared with pure TiO 2 , a redundant peak was obtained at 533 eV, which was identified for the surface H 2 O ...
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... than Mn, when Ti 5c is bonded to -O-Mn, coordination changes from octahedral to tetrahedral; therefore, the positive shift in the Ti 2p binding energy could be attributed to the change in the coordination number of titanium via the formation of a Ti-O-Mn bond at the TiO 2 -cocatalyst interface. The O 1s spectrum of Ag-TiO 2 -MnO x (40%), shown in Fig. 5A, exhibited a similarly positive shift after dual loading of Ag and MnO x , thus confirming the formation of the Ti-O-Mn bonds. Moreover, for Ag-TiO 2 -MnO x (40%), the adsorbed oxygen to lattice oxygen ratio is ...
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... It has been believed that DAPs exposing two {001} and eight {101} facets have a high level of photocatalytic activity because photoexcited electrons and positive holes migrate to the {101} and {001} facets, respectively, resulting in efficient charge separation [12][13][14][15][16][17][18][19][20][21][22][23]. However, since such "charge separation" cannot be observed directly as mentioned above, the reason seems to be just speculation or a hypothesis proposed on the basis of microscopic observations of metal-and metal oxide-deposited DAPs through photocatalytic reduction and oxidation from their precursors on {101} and {001} facets, respectively [12][13][14][15][16][17][18][19][20]. ...
Facet-selective gold or platinum-nanoparticle deposition on decahedral-shaped anatase titania particles (DAPs) exposing {001} and {101} facets via photodeposition (PD) from metal-complex sources was reexamined using DAPs prepared with gas-phase reaction of titanium (IV) chloride and oxygen by quantitatively evaluating the area deposition density on {001} and {101} and comparing with the results of deposition from colloidal metal particles in the dark (CDD) or under photoirradiation (CDL). The observed facet selectivity, more or less {101} preferable, depended mainly on pH of the reaction suspensions and was almost non-selective at low pH regardless of the deposition method, PD or CDL, and the metal-source materials. Based on the results, the present authors propose that facet selectivity is attributable to surface charges (zeta potential) depending on the kind of facets, {001} and {101}, and pH of the reaction mixture and that this concept can explain the observed facet selectivity and possibly the reported facet selectivity without taking into account facet-selective reaction of photoexcited electrons and positive holes on {101} and {001} facets, respectively.
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It is very essential to improve the activity and selectivity of photothermocatalysis (PTC) by tailoring the microstructures of photothermocatalytic materials. Herein, we exploit a facet‐heterojunction strategy to fabricate photothermocatalysts, by which CdS−Au‐{001}BiOCl{110}‐MnOx is constructed by respectively depositing CdS−Au on the {001} facets and MnOx on {110} facets of BiOCl nanosheets. This material exhibits excellent activity for toluene oxidation and near 100 % selectivity from toluene to carbon dioxide under full‐spectrum sunlight irradiation. The conversion rate of toluene under PTC condition is significantly enhanced by 47.5, 1.8 and 1.7 times compared with that of sole PC, TC and the sum of TC and PC. There is a synergistic effect between photocatalysis and thermocatalysis, in which the S‐scheme photocatalyst CdS−Au‐{001}BiOCl produces high‐energy active species to activate toluene and accelerate the cycle conversion of lattice oxygen and oxygen vacancy in MnOx.
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