摘要
Ag_2O是优良的感光材料,很少作为光催化材料,而常被用作光催化材料的共催化剂.此外,由于Ag_2O禁带宽度窄,且可有效吸收近红外光,因而不能用于全太阳光谱的光催化应用中.同时很少被用作NIR催化剂.本文中不仅研究了纳米Ag_2O颗粒的UV-Vis光催化性能,而且还系统探究了其NIR光催化活性.由于在紫外线和可见光的照射下,Ag_2O纳米颗粒易发生光还原失活,因而对Ag_2O表面硫化处理,使其表面上生长Ag_2S_2O_7层以形成Ag_2S_2O_7/Ag_2O异质结,探究了该异质结UV-Vis光催化活性及其光催化循环稳定性;同时,考察了其近红外光催化及其重复使用性能.利用沉淀法成功制备了Ag_2O纳米颗粒,并通过在其表面部分硫化处理得到Ag_2S_2O_7,成功构筑Ag_2S_2O_7/Ag_2O异质结构,并研究了该Ag_2S_2O_7/Ag_2O异质结构UV-Vis-NIR光催化降解有机污染物性能.研究表明,Ag_2O纳米颗粒在光子能量较低的NIR照射条件下具有较强的光催化活性,但UV-Vis照射下,虽然Ag_2O具有光催化活性,但易发生光还原生成单质银,降低其光催化稳定性;Ag_2S_2O_7/Ag_2O纳米异质结,虽然在UV-Vis-NIR范围内光催化活性略降于Ag_2O,但稳定性显著提高,总体来看,Ag_2S_2O_7/Ag_2O异质结构在全光谱催化方面更具优势.这主要是由于Ag_2O表面部分硫化得到的Ag_2S_2O_7纳米颗粒,且二者之间能带匹配促进了光生载流子分离,同时Ag_2O表面的Ag_2S_2O_7颗粒直接吸收能量较高的UV-Vis,进而保护内部Ag_2O,抑制了其自身还原,可显著提高Ag_2S_2O_7/Ag_2O异质结在UV-Vis-NIR催化活性及稳定性.实验结果分析表明,Ag_2S_2O_7/Ag_2O异质结纳米颗粒在UV-Vis-NIR条件下均具有稳定且高效的光催化活性,其主要原因为:(1)具有窄带隙的Ag_2O可有效拓宽该异质结的光谱吸收;(2)Ag_2S_2O_7/Ag_2O异质结能带匹配可有效促使光生载流子分离;(3)Ag_2O颗粒表面的Ag_2S_2O_7纳米颗粒可有效提高Ag_2S_2O_7/Ag_2O异质结纳米颗粒的光化学稳定性,尤其是在UV-Vis条件下的化学稳定性.Ag_2O纳米颗粒受到光照(UV-Vis-NIR)激发后产生电子-空穴对,由于Ag_2S_2O_7与Ag_2O能带位置的匹配,Ag_2O导带的光生电子注入Ag_2S_2O_7的导带;而Ag_2S_2O_7价带的光生空穴注入Ag_2O的价带.Ag_2O表面的Ag_2S_2O_7颗粒可有效捕捉电子,从而阻止Ag_2O产生的电子-空穴对复合,进而提高光催化活性;同时当光子能量较高(UV以及部分短波长的Vis)时,Ag_2O表面的Ag_2S_2O_7颗粒直接吸收该部分光能,进而保护内部Ag_2O发生自身还原,因此,Ag_2S_2O_7/Ag_2O异质结纳米颗粒在UV,Vis及NIR条件下均具有稳定且高效的光催化活性,在高效利用全光谱光催化降解有机污染物方面具有较大的潜力.
Ag2O has attracted much recent attention,because of its high photocatalytic activity in the ultraviolet(UV)‐visible region.However,there have been few reports on the near‐infrared(NIR)photocatalytic activity of Ag2O.This paper reports the high NIR photocatalytic activity of Ag2O nanoparticles.Ag2O is unsuitable for application in full‐solar‐spectrum photocatalysis,because it is unstable under UV irradiation.A surface sulfurization process was carried out to address this issue.Specifically,a layer of Ag2S2O7nanoparticles was grown on the surface of the Ag2O nanoparticles,to improve the stability of the Ag2O photocatalyst and enhance its photocatalytic activity in the UV,visible and NIR regions.The Ag2O/Ag2S2O7heterostructure is a stable and efficient full‐solar‐spectrum photocatalyst.It has potential application in the photodegradation of organic pollutants,and more generally in environmental engineering where full utilization of the solar spectrum is required.
作者
李海东
陈廷翰
王瑶
唐建国
王亚娜
桑元华
刘宏
Haidong Li;Tinghan Chen;Yao Wang;Jianguo Tang;Yana Wang;Yuanhua Sang;Hong Liu(Institute of Hybrid Materials, Qingdao University, Qingdao 266071, Shandong, China;Grade 1506, The High School Attached to Tsinghua University, Beijing 100084, China;State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, Shandong, China)
基金
supported by the National Natural Science Foundation of China(51372142)
the Innovation Research Group(51321091)
the Program of Introducing Talents of Discipline to Universities in China(111 program,b06015)~~
