Highly Efficient Photoinduced Enhanced Raman Spectroscopy (PIERS) from Plasmonic Nanoparticles Decorated 3D Semiconductor Arrays for Ultrasensitive, Portable, and Recyclable Detection of Organic Pollutants

Abstract

Semiconductor materials have become competitive candidates for surface-enhanced Raman scattering (SERS) substrates; however, their limited SERS sensitivity hinders the practical applications of semiconductors. Here, we develop a hybrid substrate by integrating anatase/rutile TiO 2 heterostructure with dense plasmonic hotspots of Ag nanoparticle (AgNPs) for efficient photoinduced enhanced Raman spectroscopy (PIERS). The PIERS mechanism is systematically investigated by means of a portable Raman instrument. When ultraviolet (UV) light irradiates the substrate, the TiO 2 −Ag hybrid arrays produce remarkable charge-transfer enhancement, which can be ascribed to the highly efficient charge separation driven by heterojunction and transfer from TiO 2 heterostructure to AgNPs. This platform allows for the rapid detection of multifold organic species, including malachite green (MG), crystal violet (CV), rhodamine 6G (R6G), thiram, and acephate, and as high as 27.8-fold enhancement over the normal SERS is achieved, representing the highest PIERS magnification up to the present time. The intensive PIERS enhancement makes it ultrasensitively detect analyte concentration of an order of magnitude lower than that of SERS method. The improved sensitivity and resolution can be readily realized by simple UV irradiation, which represents a major advantage of our PIERS methodology. Besides, the integration of uniform TiO 2 heterostructure arrays with AgNPs generates superior signal reproducibility with relative standard deviation (RSD) value of less than 14%. In addition, the detected molecules on the substrate can be eliminated by photocatalytic degradation after PIERS measurements by using UV irradiation, which makes the substrate reusable for 15 cycles. The ultrahigh sensitivity, superior reproducibility, and excellent recyclability displayed by our platform may provide new opportunities in field detection analysis coupled with a portable Raman instrument.

New Mechanism for Long Photo‐Induced Enhanced Raman Spectroscopy in Au Nanoparticles Embedded in TiO2

“…PIERS has already been demonstrated successful on a diversity of molecules: Raman probes, [27][28][29]31] biomolecules (DNA, [32] tyrosine, [33] and glucose [27] ), explosives, [27,34] and organic pollutants. [35,36] It has also been used for the study of V O dynamics in semiconductors. [37,38] Nevertheless, this technique is still young and, as Zhao et al are pointing out in their 2021 review, [39] several issues must still be addressed.…”

Recent Development of SERS Technology: Semiconductor-Based Study

“…For the novel SERS discoveries, a new material model needs to be developed that places high demands on the design and preparation of materials for applications (Figure 3). 19…”

“…Schematic illustration of the synthesis process of anatase nanosheets/rutile nanorod TiO 2 heterostructures decorated with AgNP hybrid arrays for photoinduced enhanced Raman spectroscopy detection. (Reproduced with permission from ref (19). Copyright 2019, American Chemical Society.…”

Modified Absorption and Emission Properties Leading to Intriguing Applications in Plasmonic–Excitonic Nanostructures

“…d) Reproduced with permission. [ 376 ] Copyright 2019, ACS Publications. e) Reproduced with permission.…”

“…In a recent study based on Ag/TiO 2 hybrids, PIERS (photoinduced enhanced Raman spectroscopy) has been demonstrated to be more sensitive with nearly 28 times enhanced sensitivity over SERS. [ 376 ] When Ag/TiO 2 substrates irradiated by UV radiation, energy transfer takes place from TiO 2 to Ag NPs, thus enhancing Raman intensity. The Raman intensity (PIERS scan) reaches a maximum under UV irradiation and then relaxes after it was turned off whereas no enhancement was recorded in SERS scan, shown in Figure 22d.…”