Rhodium concave nanocubes and nanoplates as deep‐UV resonant SERS platform

Abstract

We report on the detection of molecules at the trace level using deep‐UV surface‐enhanced Raman spectroscopy (SERS) on shape‐anisotropic rhodium (Rh) nanoparticles. Rh nanoparticles of three distinct morphologies, triangular nanoplates, rectangular nanoplates, and concave nanocubes, that exhibit strong plasmon resonances in the UV range were exploited for deep‐UV SERS. With an enhancement factor greater than 105, Rh concave nanocubes demonstrate the highest SERS activity, which is well corroborated by electric field distribution maps calculated using finite‐difference time‐domain (FDTD) simulations. The deep‐UV SERS substrate based on Rh concave nanocubes enables the detection of trace levels of explosive molecules such as p‐nitrobenzoic acid and 2,4‐dinitrotoluene with detection limits of 10−10 M and 10−7 M, respectively, and ammonium nitrate with a detection limit of 10−12 M. Deep‐UV SERS detection of explosive molecules on a low‐cost and simple‐to‐fabricate Rh nanoparticles substrate holds tremendous potential for the SERS‐based identification of hazardous materials.

Beyond the Visible: A Review of Ultraviolet Surface-Enhanced Raman Scattering Substrate Compositions, Morphologies, and Performance

“…Additionally, the nanohole arrays could detect and distinguish between mutations in oligonucleotides, such as 12-mer singlestranded DNA. Lastly, we highlight Rh NPs for their reasonable EF of ~10 5 and excellent LOD of ~10 −13 M [45]. Thus far, this is the only non-Al substrate used in our analysis for DUV-SERS studies.…”

“…From 2008 to the present, researchers have been exploring different combinations of elemental composition and substrate morphology, as illustrated in Figure 3. The variety of elemental compositions explored encompasses the traditional coinage metals (Au, Ag, Cu) [36,37,[39][40][41]43], transition metals (Co, Pd, Pt, Rh, Ru) [4,35,38,[43][44][45], Group 3A metals (Al, Ga, In) [42,, 2D materials (SnS 2 , SnSe 2 ) [67,68], alloys (Al-Mg) [69,70], and oxides (ZnO) [71]. We defined five substrate morphology categories to simplify the analysis: 2D materials, electrodes, NPs, and nanostructures (NSs).…”

“…An asterisk (*) denotes if a resonant analyte was used in the reported performance metrics. The citations for the DUV substrates from left to right: Al FON [49], Al NVA [62], Al bow-tie antenna [61], Rh CNC [45], Al NHA [53]. The citations for the UV substrates from left to right: Al NCA [59], Al NS [56], Ga NS [64], Al 3D NS [46], Al NP film [50], In@SiO 2 [65], Al NHA [47], Al HMDG [57].…”

“…Detecting environmentally or militarily relevant analytes, including water and soil contaminants, chemical warfare agents, and explosive compounds, has been explored with visible and UV-SERS [45,[88][89][90]. Compared to visible wavelengths, UV excitation affords increased Raman scattering intensities, mitigation of PL interference, and higher spatial resolution (see Section 2.1).…”

Key Factors for Controlling Plasmon-Induced Chemical Reactions on Metal Surfaces

“…For catalytic applications, metal nanocrystals must be stable during chemical reactions and the synthesis of nanocrystals with precisely controlled sizes and structures should be established. Among the metals available in the UV region, Al and Rh have been reported as materials for chemically stable plasmonic metal catalysts. , However, the synthesis of well-controlled structures of their nanocrystals is difficult, and there are few reports on their preparation to achieve the tuning energy of UV plasmons (Figure c). − …”