Hydrothermal synthesis of visible light-sensitive conduction band-controlled tungsten-doped titanium dioxide photocatalysts with copper ion-grafts

Abstract

We prepared titanium dioxide (TiO 2 ) photocatalysts sensitive to visible light, namely copper(II) [Cu(II)]-grafted tungsten and gallium co-doped TiO 2 (Ti 1¹3x W x Ga 2x O 2 , x value is up to 0.12), based on the concept of narrowing the band gap of TiO 2 by positively shifting its conduction band (CB) edge to a lower energy level and the catalytic multi-electron reduction of oxygen by Cu(I) ions [H. Yu, H. Irie, K. Hashimoto, J. Am. Chem. Soc., 132, 6898 (2010)]. Using this approach, the optical band-gap energy of TiO 2 was decreased to ³2.8 eV, and band-gap narrowing was confirmed by measuring the action spectrum for oxygen evolution from water in the presence of iron ions [Fe(III), from FeCl 3 ]. The Cu(II)-grafted Ti 1¹3x W x Ga 2x O 2 (x = 0.12) photocatalyst effectively decomposed 2-propanol to carbon dioxide (CO 2 ) via acetone under visible light (400530 nm, 1 mW/cm 2 ) with a CO 2 -generation rate of 0.30¯mol/h. Grafting Cu(II) ions after the hydrochloric acid treatment of Ti 1¹3x W x Ga 2x O 2 (x = 0.12) increased the CO 2 -generation rate to 0.40¯mol/h.

Formation of Micrometer Scale Metal Structures on Glass by Selective Electroless Plating on Photopatterned Titanium and Copper Containing Films

“…Despite Cu excretion from the TiO 2 layer and displacement with Pd, SEM observation of the TiO 2 layers after delamination and STEM observation of plated TiO 2 layers cross-sectional slices showed dense copper rich TiO 2 layers after plating (Figures S2–S5, S10, and S12). Reduction in the valence band level of TiO 2 has been reported by grafting nanometer sized metal particles, like Cu, Ru, Pd, Au, or Pt, onto TiO 2 particles has been reported, which had resulted in photocatalytic reaction occurrence with longer wavelength light for metal@TiO 2 compared to TiO 2 alone. , The Cu@TiO 2 structure in the reduced layer and Pd@TiO 2 after the displacement treatment may have a decreased activation energy for catalytic formaldehyde oxidation compared to copper or palladium alone resulting in increased catalytic activity. Higher catalytic activity of copper and palladium particles within the Si/TiO 2 matrix could have also assisted the initial deposition in the porous Si/TiO 2 region such that the layer was filled with electroless copper as opposed to deposition initiated from the large Cu or Cu/Pd particles adhered to the TiO 2 surface.…”

Designs of composite photocatalysts for their enhanced performance based on photoinduced charge transfer

“…We selected W 6+ and Ga 3+ ions to be substituted at Ti 4+ sites to control the CB of TiO 2 because W 6+ (W 5d) contributes to the electronic structure of the CB of TiO 2 and Ga 3+ acts as a counter dopant to maintain the charge neutrality (Ti 1¹3x W x Ga 2x O 2 ). 30), 31) Figure 6 shows the absorption spectra of Ti 1¹3x W x Ga 2x O 2 (x = 0, 0.03) and Cu 2+ / Ti 1¹3x W x Ga 2x O 2 (x = 0.03) obtained by the diffuse reflection method. The spectra clearly indicate that the doping of W 6+ (and Ga 3+ ) at the Ti 4+ sites narrowed the bandgap of TiO 2 (R) and that the absorption edges shifted to a longer wavelength region.…”

Ultrasonic spray pyrolysis assembly of a TiO2–WO3–Pt multi-heterojunction microsphere photocatalyst using highly crystalline WO3 nanosheets: less is better

“…The reason for the high activity of Pt-WO 3 was due to the promotion of multi-electron reduction of O 2 on the Pt cocatalyst rather than single-electron reduction. Hashimoto et al grafted Cu(II) or Fe(III) species onto a series of oxides, such as Ti 1À3x W x Ga 2x O 2 , 21 (Sr 1Ày Na y )(Ti 1Àx Mo x )O 3 , 22 Ti 3+ self-doped TiO 2 23 and Fe doped TiO 2 . 24 The grafted species consistently enhanced the photocatalytic activity toward the degradation of isopropyl alcohol induced by interfacial charge transfer (IFCT) processes and thereafter consumption in the multi-electron reduction of O 2 mediated by the surface clusters.…”