Opt Express. 2021 Sep 13;29(19):30045-30061. doi: 10.1364/OE.434275.
We report results from our extensive studies on the fabrication of ultra-thin, flexible, and cost-effective Ag nanoparticle (NP) coated free-standing porous silicon (FS-pSi) for superior molecular sensing. The FS-pSi has been prepared by adopting a simple wet-etching method. The deposition time of AgNO has been increased to improve the number of hot-spot regions, thereby the sensing abilities are improved efficiently. FESEM images illustrated the morphology of uniformly distributed AgNPs on the pSi surface. Initially, a dye molecule [methylene blue (MB)] was used as a probe to evaluate the sensing capabilities of the substrate using the surface-enhanced Raman scattering (SERS) technique. The detection was later extended towards the sensing of two important explosive molecules [ammonium nitrate (AN), picric acid (PA)], and a pesticide molecule (thiram) clearly demonstrating the versatility of the investigated substrates. The sensitivity was confirmed by estimating the analytical enhancement factor (AEF), which was ∼10 for MB and ∼10 for explosives and pesticides. We have also evaluated the limit of detection (LOD) values in each case, which were found to be 50 nM, 1 µM, 2 µM, and 1 µM, respectively, for MB, PA, AN, and thiram. Undeniably, our detailed SERS results established excellent reproducibility with a low RSD (relative standard deviation). Furthermore, we also demonstrate the reasonable stability of AgNPs decorated pSi by inspecting and studying their SERS performance over a period of 90 days. The overall cost of these substrates is attractive for practical applications on account of the above-mentioned superior qualities.
我们报告了在制造超轻薄、灵活且具有成本效益的 Ag 纳米颗粒（NP）涂覆的独立式多孔硅（FS-pSi）方面的广泛研究结果，用于优异的分子传感。FS-pSi 通过采用简单的湿法刻蚀方法制备。增加 AgNO 的沉积时间以增加热点区域的数量，从而有效地提高了传感能力。FESEM 图像说明了均匀分布在 pSi 表面上的 AgNPs 的形态。最初，使用染料分子[亚甲蓝（MB）]作为探针，使用表面增强拉曼散射（SERS）技术评估基底的传感能力。随后，将检测扩展到对两种重要爆炸物分子[硝酸铵（AN），苦味酸（PA）]和农药分子（福美双）的传感，清楚地证明了所研究基底的多功能性。通过估计分析增强因子（AEF）来确认灵敏度，对于 MB 和爆炸物和农药而言，AEF 分别约为 10 和 10。我们还评估了每种情况下的检测限（LOD）值，对于 MB、PA、AN 和福美双，发现分别为 50 nM、1 µM、2 µM 和 1 µM。不可否认，我们详细的 SERS 结果具有出色的重现性和低 RSD（相对标准偏差）。此外，我们还通过检查和研究 AgNPs 装饰的 pSi 在 90 天内的 SERS 性能来证明其具有合理的稳定性。这些基底的总体成本具有吸引力，因为它们具有上述优异的品质。
