Zheng Xinlu, Wu Xiao, Zhang Letian, Kang Jianjian, Zhou Man, Zhong Yang, Zhang Jinlong, Wang Lingzhi
Shanghai Engineering Research Center for Multi-Media Environmental Catalysis and Resource Utilization, Key Lab for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Feringa Nobel Prize Scientist Joint Research Center, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science & Technology 130 Meilong Road Shanghai 200237 China
Chem Sci. 2022 Oct 12;13(42):12560-12566. doi: 10.1039/d2sc03998b. eCollection 2022 Nov 2.
The intrinsic electronic states of transition metal-containing SERS substrates, especially the effect of spin state on the detection sensitivity, still remain unknown. Herein, we propose a simple co-precipitation approach to form trimetallic MIL-101(FeNiTi) with high-spin (HS) Fe as a result of geometric distortion of the octahedral symmetry. Using methylene blue as a demonstration, the trimetallic MIL-101(FeNiTi) shows a high enhancement factor (EF) of 6.1 × 10, a low detection limit of 10 M and excellent detection stability after long-term preservation. X-ray absorption fine structure and photoelectron spectra demonstrate that coupling between high-spin Fe and aliovalent transition metals Ni and Ti with different filling degree of 3d e-orbitals results in electron delocalization. The DFT calculation suggests that MIL-101(FeNiTi) with high-spin Fe favors molecular adsorption and the charge transfer from the molecule to MIL-101(FeNiTi) is promoted, benefitting from the enhanced electron delocalization, which both contribute to the distinguished SERS performance of MIL-101(FeNiTi). This finding provides in-depth mechanistic understanding of the effect of the spin state of transition metals on mediating SERS activity, which is expected to efficiently promote the development of SERS platforms based on non-noble metals.
含过渡金属的表面增强拉曼散射（SERS）基底的本征电子态，尤其是自旋态对检测灵敏度的影响，仍然未知。在此，我们提出一种简单的共沉淀方法来形成三金属MIL-101(FeNiTi)，由于八面体对称性的几何畸变，其中铁为高自旋（HS）态。以亚甲基蓝为例，三金属MIL-101(FeNiTi)显示出6.1×10的高增强因子（EF）、10 M的低检测限以及长期保存后的优异检测稳定性。X射线吸收精细结构和光电子能谱表明，高自旋铁与具有不同3d e轨道填充度的异价过渡金属镍和钛之间的耦合导致了电子离域。密度泛函理论计算表明，具有高自旋铁的MIL-101(FeNiTi)有利于分子吸附，并且促进了从分子到MIL-101(FeNiTi)的电荷转移，这得益于增强的电子离域，二者都有助于MIL-101(FeNiTi)卓越的SERS性能。这一发现为过渡金属自旋态对介导SERS活性的影响提供了深入的机理理解，有望有效促进基于非贵金属的SERS平台的发展。
