Preparation of Au/TiO2 with Metal Cocatalysts Exhibiting Strong Surface Plasmon Resonance Effective for Photoinduced Hydrogen Formation under Irradiation of Visible Light
Preparation of Au/TiO2 with Metal Cocatalysts Exhibiting Strong Surface Plasmon Resonance Effective for Photoinduced Hydrogen Formation under Irradiation of Visible Light
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DOI：
10.1021/cs3006499
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发表时间：
2013-01-01
期刊：
影响因子：
12.9
通讯作者：
Kominami, Hiroshi
中科院分区：
文献类型：
--
作者：
Tanaka, Atsuhiro;Sakaguchi, Satoshi;Kominami, Hiroshi
通过在空穴清除剂（PH）存在下的Pt的传统光沉积和随后在空穴清除剂（CPH）存在下的Au胶体光沉积到TiO 2-Pt上的组合，成功地制备了具有小的Pt（Pt）纳米颗粒和大的金（Au）颗粒的TiO 2，而没有合金化和纳米颗粒凝聚。平均直径为13 nm的Au颗粒固定在TiO 2和TiO 2-Pt样品上，而不改变Au颗粒的原始尺寸，并且由于Au的表面等离子体共振（SPR），Au颗粒的大尺寸归因于Au/TiO 2和Au/TiO 2 Pt样品在550 nm附近表现出强的光吸收。采用裸TiO 2、TiO 2-Pt、Au/TiO 2和Au/TiO 2-Pt样品，在可见光照射下，由异丙醇在水溶液中光诱导生成H-2。前两个样品对可见光无响应，不产生H-2，后两个样品产生H-2，表明负载Au粒子的SPR光吸收对可见光照射下H-2的产生有贡献。Au/TiO 2-Pt样品的H-2形成速率比无Pt的Au/TiO 2样品的H-2形成速率大7倍，表明负载在TiO 2上的Pt纳米颗粒有效地充当助催化剂，即作为H-2释放的还原位点。PH法和CPH法相结合可有效地制备含有其他金属助催化剂（M）（包括Au）的Au/TiO 2，即Au/TiO 2 Au，且H-2析出速率按M; Pt > Pd > Ru > Rh > Au > Ag > Cu > Jr的顺序降低。该速率与M的氢过电压（HOV）之间的负相关性，即，观察到HOV越高，通过光生电子还原质子越困难。由于负载在TiO 2上的Au和M的量独立地改变，因此检查了对光吸收和H-2释放速率的影响。由于SPR的光吸收率之间的线性相关性被观察到，表明由Au颗粒的SPR光吸收是决定H-2的演变速度的重要因素之一。
Titanium(IV) oxide (TiO2) having both small platinum (Pt) nanoparticles and large gold (Au) particles without alloying and nanoparticle coagulation was successfully prepared by the combination of traditional photodeposition of Pt in the presence of a hole scavenger (PH) and subsequent Au colloid photodeposition in the presence of a hole scavenger (CPH) onto TiO2-Pt. Au particles having an average diameter of 13 nm were fixed on both TiO2 and TiO2-Pt samples without change in the original size of Au particles, and the Au/TiO2 and Au/TiO2 Pt samples exhibited strong photoabsorption around 550 nm as a result of surface plasmon resonance (SPR) of Au to which the large size of Au particles was attributed. Bare TiO2, TiO2-Pt, Au/TiO2, and Au/TiO2-Pt samples were used for photoinduced hydrogen (H-2) formation from 2-propanol in aqueous solutions under irradiation of visible light. The first two samples yielded no H-2 because of no response to visible light, but the latter two formed H-2, indicating that SPR photoabsorption of supported Au particles contributed to the H-2 evolution under irradiation of visible light. The H-2 formation rate of the Au/TiO2-Pt sample was similar to 7-times larger than that of the Pt-free Au/TiO2 sample, indicating that Pt nanoparticles loaded on TiO2 acted effectively as a cocatalyst, that is, as reduction sites for H-2 evolution. The combination of the PH and CPH methods was effective for preparation of Au/TiO2 having other metal cocatalysts (M) including Au, that is, Au/TiO2 Au, and H-2 evolution rates decreased in the order of M; Pt > Pd > Ru > Rh > Au > Ag > Cu > Jr. An inverse correlation between the rate and the hydrogen overvoltage (HOV) of M, that is, it was observed that the higher the HOV, the more difficult it is to reduce protons by photogenerated electrons. Since the amounts of Au and M loaded on TiO2 were changed independently, the effects on photoabsorption and the rate of H-2 evolution were examined. A linear correlation was observed between rate and light absorption due to SPR, suggesting that SPR photoabsorption by Au particles was one of the important factors determining the rate of the H-2 evolution.