Photocatalytic reactions under irradiation of visible light over gold nanoparticles supported on titanium(IV) oxide powder prepared by using a multi-step photodeposition method
Photocatalytic reactions under irradiation of visible light over gold nanoparticles supported on titanium(IV) oxide powder prepared by using a multi-step photodeposition method
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DOI：
10.1039/c4cy00042k
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发表时间：
2014-06
影响因子：
5
通讯作者：
A. Tanaka;S. Sakaguchi;K. Hashimoto;H. Kominami
中科院分区：
文献类型：
--
作者：
A. Tanaka;S. Sakaguchi;K. Hashimoto;H. Kominami
通过多步（MS）光沉积方法成功地制备了具有较小和较大金（Au）颗粒的氧化钛（IV）（TiO 2）。当0.25重量%的Au负载每次光沉积重复四次，较小和较大的Au颗粒的平均直径分别为1.4和13 nm，被固定在TiO 2上，和Au/TiO 2样品表现出强的光吸收约550 nm，由于表面等离子体共振（SPR）的较大的Au颗粒。通过改变每次光沉积的Au负载量和光沉积次数制备了各种Au/TiO 2样品。研究了MS光沉积条件和样品焙烧对Au粒子分布和光吸收性能的影响。这些样品用于在可见光照射下从2-丙醇形成氢（H2）和在水性悬浮液中矿化乙酸。在脱气条件下形成H2的情况下，具有较大和较小颗粒的Au/TiO 2的反应速率比不具有较小Au颗粒的Au/TiO 2样品的反应速率高4倍，表明较小的Au颗粒有效地充当助催化剂，即充当H2析出的还原位点。另一方面，在乙酸在曝气条件下的矿化的情况下，二氧化碳的形成速率是独立的存在下的较小的Au颗粒，表明较小的Au颗粒上的乙酸的矿化的影响不大。为了扩展Au/TiO 2在可见光照射下形成H2的可能性，在脱气条件下检查了作为生物质废物的氨（NH3）的H2形成; NH3以3：1的化学计量比分解为H2和氮气。
Titanium(IV) oxide (TiO2) having both smaller and larger gold (Au) particles was successfully prepared by a multi-step (MS) photodeposition method. When 0.25 wt% Au loading per photodeposition was repeated four times, smaller and larger Au particles having average diameters of 1.4 and 13 nm, respectively, were fixed on TiO2, and the Au/TiO2 sample exhibited strong photoabsorption around 550 nm due to surface plasmon resonance (SPR) of the larger Au particles. Various Au/TiO2 samples were prepared by changing the Au loading per photodeposition and the number of photodepositions. Effects of the conditions in MS photodeposition and sample calcination on Au particle distribution and photoabsorption properties were investigated. These samples were used for hydrogen (H2) formation from 2-propanol and mineralization of acetic acid in aqueous suspensions under irradiation of visible light. In the case of H2 formation under deaerated conditions, the reaction rate of Au/TiO2 having both larger and smaller particles was 4 times higher than that of the Au/TiO2 sample without smaller Au particles, indicating that smaller Au particles acted effectively as a co-catalyst, that is, as reduction sites for H2 evolution. On the other hand, in the case of mineralization of acetic acid under aerated conditions, carbon dioxide formation rates were independent of the presence of smaller Au particles, indicating that the smaller Au particles had little effect on the mineralization of acetic acid. To extend the possibility of Au/TiO2 for H2 formation under irradiation of visible light, H2 formation from ammonia (NH3) as biomass waste was examined under deaerated conditions; NH3 was decomposed to H2 and nitrogen with a stoichiometric ratio of 3 : 1.