Ag2O as a New Visible-Light Photocatalyst: Self-Stability and High Photocatalytic Activity
Ag2O as a New Visible-Light Photocatalyst: Self-Stability and High Photocatalytic Activity
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DOI：
10.1002/chem.201101032
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发表时间：
2011-07-01
影响因子：
4.3
通讯作者：
Liu, Shengwei
中科院分区：
文献类型：
--
作者：
Wang, Xuefei;Li, Shufen;Liu, Shengwei
非均相生物降解技术是一种经济有效的去除废水中有害有机污染物的方法。[1]其中最重要的目标之一是开发高效的光催化剂，可以在太阳光或荧光照射下收获可见光。对可见光敏感的TiO2基光催化剂已经通过各种策略进行了广泛的研究，例如将杂质元素掺杂到TiO2的晶格中，[2]用吸附的分子敏化TiO2，[3]与窄带隙半导体耦合，[4]以及用无机金属离子进行表面改性。[5]最近，我们已经成功地制备了一种新的可见光敏感的二氧化钛光催化剂的导带（CB）控制的二氧化钛，通过使用W掺杂和随后的表面改性与CuII。[6]除了TiO 2、WO 3之外，金属硫化物、正磷酸银和卤化物也被证明是在可见光照射下有效的光催化材料。[7-9]然而，可见光光催化剂的种类仍然非常有限。因此，开发对可见光特别是荧光灯具有敏感性的新型高效光催化材料是一个非常重要和具有挑战性的课题。Ag2O是一种棕色粉末，具有简单的立方结构，晶格常数为0.472 nm，作为清洁剂、防腐剂、着色剂、电极材料、烷烃活化催化剂和烯烃环氧化催化剂，已被广泛应用于许多工业领域。[10据报道，Ag2O的带隙能量为1.2eV，CB边缘的能级为+0.2eV（相对于SHE）。[12]然而，由于光敏性和在光照射下的不稳定性，Ag2O很少被用作主要的光催化材料，除了作为助催化剂。[13]通过吸收入射光，Ag2O分解成Ag原子和AgO（AgO，一种混合价的氧化物，可以描述为Ag2O和Ag3O2的组合）。[14与Ag2O相比，AgO相在室温下是不稳定的，并且可以容易地光还原以形成金属Ag和O2。[16]Ag2O的光分解可以描述如下：
Heterogeneous photocatalysis has been considered as a cost-effective alternative for the removal of hazardous organic contaminants from wastewater.[1] One of the most important objectives is to develop efficient photocatalysts that can harvest visible light under sunlight or fluorescent-light irradiation. TiO2-based photocatalysts that are sensitive to visible light have been widely investigated by various strategies, such as doping foreign elements into the lattices of TiO2,[2] sensitization of TiO2 with absorbed molecules,[3] coupling with narrow band-gap semiconductors,[4] and surface modification with inorganic metal ions.[5] More recently, we have succeeded in the preparation of a new visible-light-sensitive TiO2 photocatalyst by conduction-band (CB) control of TiO2 by using W doping and followed by surface modification with CuII.[6] In addition to TiO2, WO3, metal sulfides, silver orthophosphate and halides have also been demonstrated to be efficient photocatalytic materials under visiblelight irradiation.[7–9] However, the variety of visible-light photocatalysts is still very limited. It is highly crucial and a great challenge to explore new and efficient photocatalytic materials that are sensitive to visible light, especially fluorescent light, which arise from indoor lamps. Ag2O, a brown powder possessing a simple cubic structure with a lattice parameter of 0.472 nm, has been widely used in many industrial fields, as cleaning agents, preservatives, colorants, electrode materials, and catalysts for alkane activation and olefin epoxidation.[10, 11] The band-gap energy of Ag2O is reported to be 1.2 eV with a energy level of the CB edge of+ 0.2 eV (vs. SHE).[12] However, owing to the photosensitive and unstable properties under light irradiation, Ag2O is seldom used as the principal photocatalytic material other than as a cocatalyst.[13] By absorbing incident light, Ag2O is decomposed into Ag atoms and AgO (AgO, an oxide with mixed valence, can be described as a combination of Ag2O and Ag3O2).[14, 15] The AgO phase is unstable at room temperature compared with Ag2O and can be readily photoreduced to form metallic Ag and O2.[16] The photodecomposition of Ag2O can be described as follows: