Cui Yongfei, Sun Huanhuan, Guo Peng
School of Materials Science and Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science and Technology, Xi'an 710021, Shaanxi, People's Republic of China.
Nanotechnology. 2020 Mar 27;31(24):245702. doi: 10.1088/1361-6528/ab7888. Epub 2020 Feb 20.
Strontium titanate (SrTiO) with perovskite structure has recently received significant attention in t he area of photocatalysis. However, challenges remain relating to its industrial applications; the high charge carrier recombination rate and low light-harvesting efficiency being the main two. Herein, a novel strategy based on fabrication of a typical n-p heterojunction has been proposed and the typical narrow-bandgap p-type semiconductor AgO was chosen to be coupled with SrTiO using a facile chemical precipitation method. The phase compositions, microstructures and optical properties of the prepared SrTiO/AgO heterostructured photocatalysts have been systematically investigated with an x-ray diffractometer, scanning electron microscope, high resolution transmission electron microscope, x-ray photoelectron spectroscope and UV-vis spectrophotometer. The photocatalytic properties were evaluated through photodegradation of a common organic dye Rhodamine B (RhB). The results demonstrated that the heterostructured photocatalyst SrTiO/AgO-0.15 outperformed pristine SrTiO and AgO. Specifically, the reaction rate of SrTiO/AgO-0.15 is about 69 times and 4 times that of bare SrTiO and AgO respectively in photodegradation of RhB. The excellent photocatalytic performance was attributed to the synergetic effect between the improved visible-light harvesting efficiency and inhibited electron-hole recombination rate arising from the built-in electric field in a p-n heterojunction, as evidenced by the transient photocurrent and photoluminescence spectrum investigation. Furthermore, the excellent recyclability of the heterostructured photocatalyst was confirmed and holes were verified to be the major active species contributing to the overall degradation. Our findings demonstrate construction of p-n heterojunctions with narrow-bandgap semiconductors as a feasible avenue to promote overall photocatalytic efficiency, through simultaneously boosting charge-carrier separation and expanding photon-absorption range.
具有钙钛矿结构的钛酸锶（SrTiO₃）最近在光催化领域受到了广泛关注。然而，其工业应用仍面临挑战；主要的两个挑战是高电荷载流子复合率和低光捕获效率。在此，提出了一种基于制备典型n-p异质结的新策略，并选择典型的窄带隙p型半导体Ag₂O，采用简便的化学沉淀法与SrTiO₃耦合。利用X射线衍射仪、扫描电子显微镜、高分辨率透射电子显微镜、X射线光电子能谱仪和紫外可见分光光度计，系统研究了制备的SrTiO₃/Ag₂O异质结构光催化剂的相组成、微观结构和光学性质。通过对常见有机染料罗丹明B（RhB）的光降解来评估光催化性能。结果表明，异质结构光催化剂SrTiO₃/Ag₂O-0.15的性能优于原始的SrTiO₃和Ag₂O。具体而言，在RhB的光降解中，SrTiO₃/Ag₂O-0.15的反应速率分别约为裸SrTiO₃和Ag₂O的69倍和4倍。优异的光催化性能归因于p-n异质结中内建电场提高了可见光捕获效率并抑制了电子-空穴复合率，瞬态光电流和光致发光光谱研究证明了这一点。此外，证实了异质结构光催化剂具有优异的可回收性，并验证了空穴是导致整体降解的主要活性物种。我们的研究结果表明，通过同时提高电荷载流子分离和扩大光子吸收范围，构建具有窄带隙半导体的p-n异质结是提高整体光催化效率的可行途径。
