Visible‐Light‐Induced Electron Transport from Small to Large Nanoparticles in Bimodal Gold Nanoparticle‐Loaded Titanium(IV) Oxide

Abstract

A key to realizing the sustainable society is to develop highly active photocatalysts for selective organic synthesis effectively using sunlight as the energy source. Recently, metal-oxide-supported gold nanoparticles (NPs) have emerged as a new type of visible-light photocatalysts driven by the excitation of localized surface plasmon resonance of Au NPs. Here we show that visible-light irradiation (l > 430 nm) of TiO 2 -supported Au NPs with a bimodal size distribution (BM-Au/TiO 2 ) gives rise to the long-range (> 40 nm) electron transport from about 14 small (ca. 2 nm) Au NPs to one large (ca. 9 nm) Au NP through the conduction band of TiO 2 . As a result of the enhancement of charge separation, BM-Au/TiO 2 exhibits a high level of visible-light activity for the one-step synthesis of azobenzenes from nitrobenzenes at 25 8C with a yield greater than 95 % and a selectivity greater than 99 %, whereas unimodal Au/TiO 2 (UM-Au/TiO 2 ) is photocatalytically inactive.

Synthesis of 3D ordered macroporous TiO2-supported Au nanoparticle photocatalysts and their photocatalytic performances for the reduction of CO2 to methane

“…The 3DOM nanostructure with a large surface area and porosity makes the reactant diffusion facile into the bulk of catalyst and hence provide fast intraparticle molecular transfer. Secondly, the introduction of Au nanoparticles in composites can effectively extend the spectral response from UV to visible area owing to Au SPR [34,35]. At last, the electrons assembled on the CB of TiO 2 and positive charges (h + ) gathered on Au nanoparticles.…”

Light-tuned selective photosynthesis of azo- and azoxy-aromatics using graphitic C3N4

“…However, in addition to the low efficiency and poor selectivity, the use of the unstable and toxic CdS photocatalyst makes this process unfavourable for industrial applications (Table 1 , entry 1). Azobenzene can be successfully synthesised at room temperature (RT) by using a Au supported TiO 2 photocatalyst (Table 1 , entry 2) 19 . A recent study has demonstrated that selective photosynthesis of azobenzene can also be realised at elevated temperature (90 °C), by using a cheaper metal (Cu) supported on graphene (Table 1 , entry 3) 17 , 20 .…”

“… a High-pressure Hg lamp (0.007 W cm −2 ) 18 b 0.01 M KOH, 300 W Xe lamp (>430 nm, 0.01 W cm −2 ) 19 c 0.01 M KOH, 300 W Xe lamp (400–800 nm, 0.15 W cm −2 ) 16 d N3 dye on TiO 2 with Pt, triethanolamine (TEOA) as scavenger, 3 W 530 nm LED 26 e 500 W Xe lamp (450–600 nm, 0.083 W cm −2 ) 24 f LED lamp (>420 nm, 30 × 3 W), Na 2 S and Na 2 SO 3 in water 23 g 0.01 M KOH, 450 nm LED (440–460 nm, 0.03 W cm −2 ) h 0.01 M KOH, 410 nm LED (400–420 nm, 0.03 W cm −2 ) …”

Biotemplated synthesis of Au loaded Sn-doped TiO2 hierarchical nanorods using nanocrystalline cellulose and their applications in photocatalysis

“…54 Au/TiO 2 heterostructure photocatalysts have attracted considerable attention due to the LSPR and high effect of charge carrier separation via the formation of a Schottky barrier at the Au/TiO 2 interface according to the previous reports. 55,56 The Au/SDT hierarchical nanorods have been achieved by loading different amount Au NPs on the surface of SDT via using the HAuCl 4 solution of 5, 20, 40, 60, 80 mL as Au precursor, named as Au/SDT-5, Au/SDT-20, Au/SDT-40, Au/SDT-60, Au/SDT-80, respectively. The different loading amounts of Au have a strong effect on the photocatalytic activity as shown in Fig.…”