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 (λ>430 nm) of TiO2 -supported Au NPs with a bimodal size distribution (BM-Au/TiO2 ) 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 TiO2 . As a result of the enhancement of charge separation, BM-Au/TiO2 exhibits a high level of visible-light activity for the one-step synthesis of azobenzenes from nitrobenzenes at 25 °C with a yield greater than 95 % and a selectivity greater than 99 %, whereas unimodal Au/TiO2 (UM-Au/TiO2 ) is photocatalytically inactive.

Adsorption experiments and density functional theory (DFT) simulations indicated that Cu(acac)2 is chemisorbed on the monoclinic sheelite (ms)-BiVO4 surface to form an O2-bridged binuclear complex (OBBC/BiVO4) like hemocyanin. Multi-electron reduction of O2 is induced by the visible-light irradiation of the OBBC/BiVO4 in the same manner as a blue Cu enzyme. The drastic enhancement of the O2 reduction renders ms-BiVO4 to work as a good visible-light photocatalyst without any sacrificial reagents. As a model reaction, we show that this biomimetic hybrid photocatalyst exhibits a high level of activity for the aerobic oxidation of amines to aldehydes in aqueous solution and imines in THF solution at 25 °C giving selectivities above 99% under visible-light irradiation.

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.

Adsorption experiments and density functional theory (DFT) simulations indicated that Cu(acac) 2 is chemisorbed on the monoclinic sheelite (ms)-BiVO 4 surface to form an O 2 -bridged binuclear complex (OBBC/BiVO 4 ) like hemocyanin. Multi-electron reduction of O 2 is induced by the visiblelight irradiation of the OBBC/BiVO 4 in the same manner as a blue Cu enzyme. The drastic enhancement of the O 2 reduction renders ms-BiVO 4 to work as a good visible-light photocatalyst without any sacrificial reagents. As a model reaction, we show that this biomimetic hybrid photocatalyst exhibits a high level of activity for the aerobic oxidation of amines to aldehydes in aqueous solution and imines in THF solution at 25 8C giving selectivities above 99 % under visiblelight irradiation.In industry, approximately 30 % of fine chemicals are produced by oxidation processes.[1] The development of "green" oxidative synthetic routes utilizing the sunlight and O 2 in the air as the energy source and oxidizing agent, respectively, is crucial for reducing CO 2 emissions and saving energy. O 2 reduction is the key process in photocatalytic reactions as well as in fuel cells and biological energy conversion. Among a variety of visible-light photocatalysts developed so far, [2] metal oxide semiconductors represented by BiVO 4 [3] are very attractive because of the moderate oxidation ability and the good physicochemical stability. Since the solar spectrum peaks at around 500 nm, the metal oxide should possess an absorption edge longer than 500 nm or a band gap (E g ) smaller than 2.5 eV for an efficient use of the sunlight. However, there is a trade-off between the visiblelight absorptivity and the driving force for O 2 reduction, i.e., the decrease in the band gap necessarily lowers the conduction band (CB) minimum or the reducing ability of the excited electrons, because the valence band (VB) maximum, mainly consisting of O2p orbitals, is almost constant (+ 2.94 V vs. standard hydrogen electrode, SHE).[4] Thus, the CB minimum for the metal oxide semiconductors with E g < 2.5 eV is located below + 0. [5] If metal oxide semiconductors with E g < 2.5 eV can be endowed with electrocatalytic activity for the multi-electron O 2 reduction, the method would be accessible for efficient and selective oxidative chemical transformation processes. A fascinating approach is the hybridization of metal oxide semiconductors exhibiting a strong absorption in the wide spectral range and molecular metal complexes with highly efficient and selective electrocatalytic activity. [6,7] Although this type of hybrid photocatalysts has recently attracted much interest for H 2 generation, [8] CO 2 reduction, [9,10] and environmental purification, [11]

A gold nanoparticle-loaded TiO(2) (Au/TiO(2))-H(2)O(2) catalytic system induces polymerization of aniline in aqueous sulfuric acid solution at room temperature to yield a polyaniline-gold-TiO(2) composite material having wide possible applications.