For the purpose of investigating the chemical enhancement of amorphous semiconductors as well as increasing the sensitivity of the surface-enhanced Raman spectroscopy (SERS) substrate, titanium dioxide (TiO2) precursors were calcined at different temperatures to generate crystallized TiO2 (c-TiO2) and amorphous TiO2 (a-TiO2) nanosheets, respectively. Afterward, a two-dimensional (2D) a-TiO2/Ag nanosheet SERS substrate was successfully fabricated using electrostatic interaction between a-TiO2 and Ag nanoparticles. In order to demonstrate a greater SERS sensitivity on a-TiO2/Ag compared to either c-TiO2 or Ag nanoparticles alone, the SERS probe molecules rhodamine 6G (R6G) and malachite green (MG) were utilized. Based on the results of SERS detections for probe molecules and contaminants, it demonstrates that a-TiO2/Ag nanosheets produce highly sensitive and repeatable Raman signals. The detectable concentration limits for R6G and MG were found to be 10-11 M and 10-10 M, respectively. And it has been determined that the system exhibits an enhancement factor (EF) of up to 1  ×  108. The limit of detection for 4-mercaptobenzoic acid and alizarin red can both reach 1  ×  10-8. Furthermore, a finite-difference time-domain simulation is performed in order to evaluate the magnetic field strength generated by Ag nanoparticles. As a result of the simulation, it is evident that the actual EF is smaller than the calculated one, leading support to the view that a-TiO2 nanosheets have a beneficial effect on the chemical enhancement of SERS.

中文翻译：

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二维非晶态二氧化钛/银 (TiO2/Ag) 纳米片作为表面增强拉曼光谱基底，用于高灵敏度检测。

为了研究非晶半导体的化学增强以及提高表面增强拉曼光谱（SERS）基底的灵敏度，二氧化钛（TiO2）前驱体在不同温度下煅烧生成结晶TiO2（c-TiO2）和分别为无定形 TiO2 (a-TiO2) 纳米片。随后，利用a-TiO2和Ag纳米颗粒之间的静电相互作用成功制备了二维（2D）a-TiO2/Ag纳米片SERS基底。为了证明与单独的 c-TiO2 或 Ag 纳米粒子相比，a-TiO2/Ag 具有更高的 SERS 灵敏度，使用了 SERS 探针分子罗丹明 6G (R6G) 和孔雀石绿 (MG)。基于探针分子和污染物的SERS检测结果，表明a-TiO2/Ag纳米片可产生高度灵敏且可重复的拉曼信号。R6G 和 MG 的可检测浓度限值分别为 10-11 M 和 10-10 M。经测定，该体系的增强因子（EF）高达1×108。4-巯基苯甲酸和茜素红的检出限均可达到1×10-8。此外，还进行了有限差分时域模拟，以评估银纳米粒子产生的磁场强度。模拟结果表明，实际 EF 明显小于计算值，这支持了 a-TiO2 纳米片对 SERS 化学增强具有有益作用的观点。