Investigating Rhodanine film formation on roughened Cu surfaces with electrochemical impedance spectroscopy and surface-enhanced Raman scattering spectroscopy

The inhibitory effect of Rhodanine (RD) on copper in acidic media has been investigated by electrochemical impedance spectroscopy (EIS) and surface-enhance Raman scattering (SERS) spectroscopy. Roughened copper was used for EIS experiments to better compare with SERS results. The EIS results show two loops in the Nyquist plot, one of which is associated with protective film growth on the rough surface after 1 h. The SERS spectra showed a marked decrease in intensity after 1 h, which is attributed to formation of thick films opaque to the laser. The film thickness after 2. h was determined to be ~200 nm from atomic force microscopy (AFM). © 2014 Elsevier Ltd.National Science Foundation: CHE-1309731NRH acknowledges a Harry G. Drickamer Fellowship. This work was supported by the National Science Foundation (CHE-1309731), which is gratefully acknowledged

On the mechanism of the electrochemical conversion of ammonia to dinitrogen on Pt(100) in alkaline environment

The electrochemical oxidation of ammonia to dinitrogen is a model reaction for the electrocatalysis of the nitrogen cycle, as it can contribute to the understanding of the making/breaking of NN, NO, or NH bonds. Moreover, it can be used as the anode reaction in ammonia electrolyzers for H2 production or in ammonia fuel cells. We study here the reaction on the N2-forming Pt(1 0 0) electrode using a combination of electrochemical methods, product characterization and computational methods, and suggest a mechanism that is compatible with the experimental and theoretical findings. We propose that N2 is formed via an ∗NH + ∗NH coupling step, in accordance with the Gerischer-Mauerer mechanism. Other NN bond-forming steps are considered less likely based on either their unfavourable energetics or the low coverage of the necessary monomers. The NN coupling is inhibited by strongly adsorbed ∗N and ∗NO species, which are formed by further oxidation of ∗NH.Catalysis and Surface Chemistr