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Enhanced Photocatalytic Degradation of Methyl Orange by Au/TiO 2 Nanoparticles under Neutral and Acidic Solutions

2018; Wiley; Volume: 3; Issue: 5 Linguagem: Inglês

10.1002/slct.201702664

2365-6549

Masaharu Tsuji, Kanako Matsuda, Mayu Tanaka, Satsuki Kuboyama, Keiko Uto, Nozomi Wada, Hirofumi Kawazumi, Takeshi Tsuji, Hiroki Ago, Jun‐ichiro Hayashi,

Advanced Nanomaterials in Catalysis

Abstract A comparative study was carried out on the degradation of methyl orange (MO) by TiO 2 and Au/TiO 2 photocatalysts in neutral and acidic solutions. Au/TiO 2 photocatalysts with an Au : Ti atomic ratio of 1.5±0.1% : 98.5±0.1% were prepared by using a microwave‐polyol method in the presence of P25 TiO 2 . Initial degradation rates of MO by TiO 2 and Au/TiO 2 were 0.13 and 0.22 min −1 at pH 7, whereas they increased to 0.96 and 3.06 min −1 at pH 2, respectively. These results indicate that the MO degradation rates are enhanced by loading Au nanoparticles on TiO 2 in neutral and acidic solutions by factors of 1.7 and 3.2, respectively. Mass spectroscopic studies lead us to conclude that major reaction products are formed by demethylation and OH addition of benzenoid form of MO in neutral solutions, whereas they are produced through ring opening and carboxylation of quinonoid form of MO after scission of a center N‐NH bond in acidic solutions. The relative importance of electron trapping and surface plasmon resonance (SPR) effects of Au nanoparticles is discussed for the enhancement of photocatalytic activity of Au/TiO 2 .