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Highly surface-enhanced Raman scattering (SERS)-active Pt and Pd layers were fabricated using dendritic Au rod (DAR) structures, prepared by simple electrodeposition, as core substrates. Electrochemical and SERS measurements using CO as a probe revealed that the SERS activity on DAR@Pt/Pd core–shell substrates originated exclusively from the Pt/Pd shell layers. The SERS enhancement factors obtained with DAR@Pt and DAR@Pd were 4.5 × 104 and 3.5 × 104, respectively. The unique structures of DAR with sharp edge sites and long-range enhancement caused by the underlying DAR cores contributed to the high activity of SERS. The well-defined and homogeneous surface morphology of DAR@Pt/Pd substrates resulted in good SERS reproducibility and stable electrochemical SERS behavior under potential excursions. The DAR@Pt and DAR@Pd substrates were used for the in-situ electrochemical SERS examination during the oxidation of formic acid (FA) at wavenumbers below 1000 cm–1, where the SERS provided unique spectral information regarding the oxidation/reduction of electrode surfaces. Based on the results of the electrochemical SERS examinations, the electrocatalytic activity of the DAR@Pt and DAR@Pd surfaces for FA oxidation was evaluated in a comparative way. The highly active and robust Pt/Pd SERS substrates could be used for the spectroelectrochemical investigation of other important electrode reactions.

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A proton source employing a nanostructured gold surface for use in (+)-mode laser desorption ionization mass spectrometry (LDI-MS) was evaluated. Analysis of perdeuterated polyaromatic hydrocarbon compound dissolved in regular toluene, perdeuterated toluene, and deuterated methanol all showed that protonated ions were generated irregardless of solvent system. Therefore, it was concluded that residual water on the surface of the LDI plate was the major source of protons. The fact that residual water remaining after vacuum drying was the source of protons suggests that protons may be the limiting reagent in the LDI process and that overall ionization efficiency can be improved by incorporating an additional proton source. When extra proton sources, such as thiolate compounds and/or citric acid, were added to a nanostructured gold surface, the protonated signal abundance increased. These data show that protons are one of the limiting components in (+)-mode LDI MS analyses employing nanostructured gold surfaces. Therefore, it has been suggested that additional efforts are required to identify compounds that can act as proton donors without generating peaks that interfere with mass spectral interpretation.