Real-Time and Tunable Substrate for Surface Enhanced Raman Spectroscopy by Synthesis of Copper Oxide Nanoparticles via Electrolysis

Abstract

Here we show the capability of copper oxide (CuO) nanoparticles formed on copper (Cu) electrodes by the electrolysis as a real time active substrate for surface enhanced Raman scattering (SERS). We have experimentally found that using just the ultra pure water as the electrolyte and the Cu electrodes, ions are extracted from the copper anode form copper oxide nanoparticles on the anode surface in matter of minutes. Average particle size on the anode reaches to 100 nm in ninety seconds and grows to about 300 nm in five minutes. This anode is used in Raman experiments in real time as the nanoparticles were forming and the maximum enhancement factor (EF) of Raman signals were over five orders of magnitude. Other metal electrodes made of brass, zinc (Zn), silver (Ag) and aluminum (Al) were also tried for the anode material for a possible real-time substrate for SERS applications. Experimentally obtained enhancement factors were above five orders of magnitude for brass electrodes like the copper but for the other metals no enhancement is observed. Electron microscope images show the cubic nanoparticle formation on copper and brass electrodes but none in the other metals studied.

Oxygen induced promotion of electrochemical reduction of CO2 via co-electrolysis

“…To understand the mechanism through which co-electrolysis of CO 2 and O 2 boosts the CO 2 RR activity, in situ SERS is employed to identify surface species presenting during the co-electrolysis 36 . The Cu microparticle catalysts employed in this work readily exhibit the surface enhancement of Raman signals, which alleviate the need to introduce SERS-inducing particles 37,38 , and is consistent with several recent studies 36,37,39 . In the Ar atmosphere ( Fig.…”

Speciation of Cu Surfaces During the Electrochemical CO Reduction Reaction

“…Cu MPs, NPs, Chem-Cu, and OD-Cu all exhibit a surface enhancement effect for Raman spectroscopy, and Au@SiO 2 is not necessary to observe Raman features of surface species (Figures 2, S11, and S12), as suggested in several recent works. 15,17,47,48 This is expected as the particulate morphology has been shown to be SERS active. 49 Control experiments show that the Raman spectra on these samples with and without Au@SiO 2 are identical within the experimental errors (Figures 2a and S13).…”

New aspects of operando Raman spectroscopy applied to electrochemical CO2 reduction on Cu foams

“…Copper electrodes are of high interest for CO 2 RR, 4,[28][29][30][31][32] and rough Cu surfaces are well-known for the surface enhancement of Raman intensities. 2,[33][34][35][36] The intensity amplification is due to the electric field enhancement occurring in the vicinity of resonantly irradiated Cu particles with localized surface plasmons. 37 Operando Raman spectroscopy has not been used very frequently for the detection of surface-adsorbed molecules in aqueous CO 2 reduction, possibly related to specific challenges involved in operando SERS.…”