Forward and backward electron transfer on Pt loaded TiO2 photocatalysts under visible-light illumination
Forward and backward electron transfer on Pt loaded TiO2 photocatalysts under visible-light illumination
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DOI：
10.1063/5.0065074
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发表时间：
2021-09
影响因子：
4
通讯作者：
Naohiro Inoue;Kyohei Shiraki;Kosaku Kato;Shu Ashimura;M. Yoshida;Akira Yamakata
中科院分区：
文献类型：
--
作者：
Naohiro Inoue;Kyohei Shiraki;Kosaku Kato;Shu Ashimura;M. Yoshida;Akira Yamakata
金属纳米粒子的表面等离子体共振（SPR）效应在装备宽禁带光催化剂（如TiO 2）方面具有多功能性，具有可见光响应性。在这方面，Au是其SPR最常用的材料，但替代材料也在积极开发中，以有效地利用从可见光到近红外区域的太阳光。在这项工作中，我们发现，Pt颗粒负载在二氧化钛也积极影响SPR诱导的闪烁。时间分辨吸收测量证实，可见光照射诱导电子从Pt到TiO 2的转移，并且这种电子注入的效率随着入射光的波长从660 nm减小到450 nm而增加。Pt上吸附的CO的振动频率的峰移的观察证实，Pt的费米能级降低的电子转移从Pt到TiO 2的进行。这些结果意味着，Pt纳米粒子可以作为敏化剂诱导电子转移从Pt到TiO 2，虽然Pt是一个众所周知的助催化剂，提高了H 2的演变，通过收集电子从TiO 2。然而，当照射光的强度增加到超过50 mW cm-2时，一部分Pt颗粒开始捕获从TiO 2注入的电子，这表明电子从一个Pt颗粒经由TiO 2的导带转移到另一个Pt颗粒在可见光照射下进行。这些相反的作用可以归因于Pt颗粒的尺寸以及注入到TiO 2中的电子密度的变化。
The surface plasmon resonance (SPR) effects of metal nanoparticles prove versatile in terms of equipping wideband-gap photocatalysts, such as TiO2, with visible-light responsiveness. In this regard, Au is the most frequently used material for its SPR, but alternative materials are also being actively developed to effectively utilize solar light from the visible to the near-infrared region. In this work, we found that Pt particles loaded on TiO2 were also active in effecting SPR-induced photocatalysis. Time-resolved absorption measurements confirmed that visible-light irradiation induces electron transfer from Pt to TiO2, and the efficiency of this electron injection increases as the wavelength of the incident light decreases from 660 to 450 nm. Observations of the peak shift of the vibrational frequency of adsorbed CO on Pt confirmed that the Fermi level of Pt decreases as the electron transfer from Pt to TiO2 proceeds. These results imply that Pt nanoparticles can act as sensitizers to induce electron transfer from Pt to TiO2, although Pt is a well-known cocatalyst that enhances H2 evolution by collecting electrons from TiO2. However, as the intensity of the irradiated light increased beyond 50 mW cm−2, a portion of the Pt particles started to capture the injected electrons from TiO2, suggesting that the electron transfer from one Pt particle to the other Pt particles via the conduction band of TiO2 proceeds under visible light illumination. These opposing roles may be ascribed to the variation in the size of Pt particles as well as density of electrons injected into TiO2.