Structure evolution and SERS activation of cuprous oxide microcrystals via chemical etching

Abstract

The morphology, composition, and structure of semiconductor nanomaterials play important roles in tuning their unique physical and chemical properties for a variety of applications. We report a facile chemical method to etch cuprous oxide microcrystals which resulted in excellent performance in surface-enhanced Raman scattering (SERS). Microscopic and spectroscopic tools were utilized to investigate the cuprous oxide structures with the chemical etching, as well as the assessment of the SERS sensitivity. The increasing SERS sensitivity can be attributed to the generation of Raman hot spots related to the etching-induced rough surface, sharp tips and edges, as well as the strong chemical interactions between the probe molecules and the SERS substrates. Our work introduced a simple method to modify the semiconductor nanomaterials and induce SERS activity, thus expanding the application area of cuprous oxide microcrystals.

Electromagnetic and Chemical Enhancements of Surface‐Enhanced Raman Scattering Spectra from Cu2O Hexagonal Nanoplates

“…The sample volumes were determined by the area of the laser spot and the penetration depth of the focused laser. To simplify the calculation for a rough surface, we assumed that the volumes of bulk PATP and adsorbed PATP molecules under the laser spots were identical 14a. The EF could then be estimated as ≈10 5 at 1143, 1392, and 1578 cm −1 (Note S1, Supporting Information), which are exceptionally higher than that of the majority of metal oxides reported …”

“…Second, chemical enhancement mechanism (CM) remains largely unknown, of which complicated interactions of target molecules on metal oxides pose the grand challenge for identifying the SERS mechanism . In fact, the experimental observations of SERS in previous reports merely take place on a certain type of nanostructured metal oxides . Therefore, in our study, we used metal‐oxide nanoplate structures to elaborate the geometric effect on EM and the contribution of specific charge‐transfer (CT) channels to CM.…”

“…The first observation of SERS arising from the adsorbed pyridine on Cu 2 O hydrosol particles and Cu 2 O‐covered Cu was reported by Kudelski et al, showing the potential of Cu 2 O to be a SERS‐active substrate. Recently, the SERS spectra of 4‐aminothiophenol (PATP) have been demonstrated on Cu 2 O nanoparticles and microcrystals 11,14a. The SERS behaviors were primarily concluded to either hierarchical porosity of nanoparticles or high roughness of etched microcrystals, where the SERS activities were stemmed from adsorbing more analytes on the large surface area and creating Raman hot spots at the rough surface.…”

Aim and shoot: molecule-imprinting polymer coated MoO3 for selective SERS detection and photocatalytic destruction of low-level organic contaminants

“…[23][24][25][26][27] On the other hand, semiconductor materials such as a-Fe 2 O 3 , Cu 2 O, MoO 3Àx , TiO 2 , and MoS 2 actually have also been revealed to be SERS-active. [28][29][30][31][32][33] However, up to now, no selective and recyclable SERS substrate simply based on semiconductor has been designed mainly due to the low sensitivity.…”

Silver-decorated hierarchical cuprous oxide micro/nanospheres as highly effective surface-enhanced Raman scattering substrates

“…Historically one of the main objectives for improving SERS activity has been to fabricate a nanostructural substrate that can provide numerous sites of strong field enhancement, so called hot spots. Hence, various morphologies of Cu 2 O such as nanowires, nanospheres, nanodendrites, and microcrystals were intensively investigated for SERS [15][16][17][18]. However, in fact, the novel Cu 2 O micro/nanospheres with dense hot spots are the one of the best candidate for enhancing the SERS activity, but there is no report on this hierarchical nanoarchitecture.…”