Rahman Mahabubur, Al-Amin Md, Kaur Amandeep, Jahan Shirin Akter, Wilson Andrew J, Ahamad Nur Uddin
Department of Chemistry, Shahjalal University of Science and Technology Sylhet, Sylhet 3114, Bangladesh.
College of Arts and Science, Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, United States.
ACS Omega. 2025 Apr 13;10(15):14940-14948. doi: 10.1021/acsomega.4c10276. eCollection 2025 Apr 22.
In this article, we discuss a simple method to prepare core-shell Ag@TiO nanoparticles (NPs) with an optimized shell thickness to engineer plasmonic photocatalysts and surface-enhanced Raman scattering (SERS) substrates. Variation in the shell (TiO) thickness was analyzed by an acid-etching method, and the deterioration of the shell was traced by monitoring the extinction spectra of both colloidal and solid-supported Ag@TiO NPs. Attainment of the optimum shell thickness was confirmed by noticing the simultaneous appearance of the LSPR absorption band (at 450 nm) of core silver nanostructures ( = ∼10 nm) and the scattering signature of the shell (TiO) in the extinction spectrum of Ag@TiO NPs. This study showed that the optimum thickness of TiO is ∼2 nm, which allowed LSPR excitation by visible light. The observed blue shift of the LSPR peak, compared to the unetched Ag@TiO NPs, with etching time indicated the size reduction of the NPs. Ag@TiO with the optimum thickness exhibited a reaction rate five times faster than that of unetched Ag@TiO under visible light irradiation. Ag@TiO NPs exhibited higher photocatalytic activity under visible light irradiation than under UV light. Furthermore, Ag@TiO NPs with the optimized thickness exhibited significantly higher SERS activity than the unetched Ag@TiO NPs. The elevated photocatalytic and SERS activities exhibited by engineered Ag@TiO NPs reveal the effectiveness of the etching process in creating a plasmonic effect in core(plasmonic)-shell (semiconductor) nanostructures.
在本文中，我们讨论了一种制备核壳结构Ag@TiO纳米颗粒（NPs）的简单方法，该方法具有优化的壳层厚度，可用于设计等离子体光催化剂和表面增强拉曼散射（SERS）基底。通过酸蚀刻法分析壳层（TiO）厚度的变化，并通过监测胶体和固体负载的Ag@TiO NPs的消光光谱来追踪壳层的劣化情况。通过观察核银纳米结构（直径约为10 nm）的局域表面等离子体共振（LSPR）吸收带（在450 nm处）和Ag@TiO NPs消光光谱中壳层（TiO）的散射特征同时出现，证实了最佳壳层厚度的实现。该研究表明，TiO的最佳厚度约为2 nm，这使得在可见光下能够激发LSPR。与未蚀刻的Ag@TiO NPs相比，随着蚀刻时间的增加，观察到LSPR峰的蓝移，这表明纳米颗粒尺寸减小。具有最佳厚度的Ag@TiO在可见光照射下的反应速率比未蚀刻的Ag@TiO快五倍。Ag@TiO NPs在可见光照射下比在紫外光下表现出更高的光催化活性。此外，具有优化厚度的Ag@TiO NPs比未蚀刻的Ag@TiO NPs表现出显著更高的SERS活性。工程化的Ag@TiO NPs所表现出的提高的光催化和SERS活性揭示了蚀刻过程在核（等离子体）-壳（半导体）纳米结构中产生等离子体效应的有效性。
