Zhang Tingting, Lei Wanying, Liu Ping, Rodriguez José A, Yu Jiaguo, Qi Yang, Liu Gang, Liu Minghua
National Center for Nanoscience and Technology , Beijing 100190 , China . Email:
Institute of Materials Physics and Chemistry , School of Sciences , Northeastern University , Shenyang 110004 , China.
Chem Sci. 2015 Jul 1;6(7):4118-4123. doi: 10.1039/c5sc00766f. Epub 2015 Apr 23.
Structure-function correlations are a central theme in heterogeneous (photo)catalysis. In this study, the geometric and electronic structure of perovskite ferroelectric KNbO nanowires with respective orthorhombic and monoclinic polymorphs have been systematically addressed. By virtue of aberration-corrected scanning transmission electron microscopy, we directly visualize surface photocatalytic active sites, measure local atomic displacements at an accuracy of several picometers, and quantify ferroelectric polarization combined with first-principles calculations. The photoreactivity of the as-prepared KNbO nanowires is assessed toward aqueous rhodamine B degradation under UV light. A synergy between the ferroelectric polarization and electronic structure in photoreactivity enhancement is uncovered, which accounts for the prominent reactivity order: orthorhombic > monoclinic. Additionally, by identifying new photocatalytic products, rhodamine B degradation pathways involving -deethylation and conjugated structure cleavage are proposed. Our findings not only provide new insights into the structure-photoreactivity relationships in perovskite ferroelectric photocatalysts, but also have broad implications in perovskite-based water splitting and photovoltaics, among others.
结构-功能相关性是多相（光）催化的核心主题。在本研究中，对分别具有正交晶型和单斜晶型的钙钛矿铁电体铌酸钾纳米线的几何结构和电子结构进行了系统研究。借助像差校正扫描透射电子显微镜，我们直接观察到表面光催化活性位点，以几皮米的精度测量局部原子位移，并结合第一性原理计算对铁电极化进行量化。评估了所制备的铌酸钾纳米线在紫外光下对罗丹明B水溶液降解的光反应活性。发现了铁电极化与电子结构在增强光反应活性方面的协同作用，这解释了显著的反应活性顺序：正交晶型>单斜晶型。此外，通过鉴定新的光催化产物，提出了涉及去乙基化和共轭结构裂解的罗丹明B降解途径。我们的研究结果不仅为钙钛矿铁电光催化剂的结构-光反应活性关系提供了新的见解，而且在基于钙钛矿的水分解和光伏等领域也具有广泛的意义。
