Tailoring Cu valence and oxygen vacancy in Cu/TiO2 catalysts for enhanced CO2 photoreduction efficiency
Tailoring Cu valence and oxygen vacancy in Cu/TiO2 catalysts for enhanced CO2 photoreduction efficiency
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DOI：
10.1016/j.apcatb.2013.01.040
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发表时间：
2013-05-02
影响因子：
22.1
通讯作者：
Li, Ying
中科院分区：
文献类型：
--
作者：
Liu, Lianjun;Gao, Fei;Li, Ying
在TiO 2光催化剂中掺入Cu物种在光催化CO2还原为燃料中是至关重要的，但对Cu价态的影响知之甚少。本文采用简单的沉淀焙烧法制备了Cu/TiO 2（P25）纳米粒子催化剂。所制备的Cu/TiO 2样品以Cu 2+物种为主。通过原位X射线光电子能谱（XPS）和漫反射红外傅里叶变换光谱（DRIFTS）分析证实，在He和H-2气氛中对样品进行热预处理后，样品表面分别转变为Cu+和Cu+/Cu-0混合物。这些在还原气氛中的热预处理也诱导了缺陷位点的形成，如氧空位和Ti 3+。在模拟太阳光照射条件下，考察了不同Cu/TiO 2催化剂在水蒸气光还原CO2反应中的催化活性，结果表明：未预处理的Cu/TiO 2催化剂的活性大小顺序为：He预处理的Cu/TiO 2催化剂的活性大小顺序为：H2预处理的Cu/TiO 2催化剂的活性大小顺序为：He预处理的Cu/TiO 2催化剂的活性大小顺序为：H2预处理的Cu/TiO 2催化剂的活性大小顺序为：He预处理的Cu/TiO 2催化剂的活性大小顺序为：H2预处理的Cu/TiO 2催化剂的活性大小顺序为：He预处理的Cu/TiO 2催化剂的活性大小顺序为：H2预处理的Cu/TiO 2催化剂的活性大小顺序为：H2预处理的Cu/TiO 2催化剂的活性顺序为：He预处理的Cu/TiO 2催化剂的活性顺序为：H2预处理的Cu/TiO 2催化剂的活性顺序为：H2预处理的Cu/TiO与未预处理的TiO 2（P25）相比，H-2预处理的Cu/TiO 2在CO和CH 4的产生上分别表现出10倍和189倍的增强。这种显著的增强主要归因于以下两个因素的协同作用：（1）表面缺陷位点的形成促进了CO2吸附和随后的电荷转移到吸附的CO2;（2）Cu+/Cu-0对的存在促进了电子和空穴在不同位点的捕获。(C)2013爱思唯尔有限公司版权所有。
The incorporation of Cu species in TiO2 photocatalysts is critical in photocatalytic CO2 reduction to fuels, but the effect of Cu valence is poorly understood. In this work, Cu/TiO2 (P25) nanoparticle catalysts were prepared by a simple precipitation and calcination method. The as-prepared Cu/TiO2 sample was dominated by Cu2+ species. Thermal pretreatment of the as-prepared samples in He and H-2 atmosphere resulted in the transition to a surface dominated by Cu+ and mixed Cu+/Cu-0, respectively, confirmed by in situ X-ray photoelectron spectroscopy (XPS) and diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses. These thermal pretreatments in reducing atmospheres also induced the formation of defect sites such as oxygen vacancies and Ti3+. The various Cu/TiO2 catalysts were tested in CO2 photoreduction with water vapor under simulated solar irradiation, and their activities were in the order of as-prepared (unpretreated) < He-pretreated < H-2-pretreated. Compared with unpretreated TiO2 (P25), the H-2-pretreated Cu/TiOs demonstrated a 10-fold and 189-fold enhancement in the production of CO and CH4, respectively. This significant enhancement was mainly attributed to the synergy of the following two factors: (1) the formation of surface defect sites promoting CO2 adsorption and subsequent charge transfer to the adsorbed CO2; (2) the existence of Cu+/Cu-0 couples that facilitate electron and hole trapping at different sites. (C) 2013 Elsevier B.V. All rights reserved.