The electrochemical double layer plays a critical role in electrochemical processes. Whilst there have been many theoretical models predicting structural and electrical organization of the electrochemical double layer, the experimental verification of these models has been challenging due to the limitations of available experimental techniques. The induced potential drop in the electrolyte has never been directly observed and verified experimentally, to the best of our knowledge. In this study, we report the direct probing of the potential drop as well as the potential of zero charge by means of ambient pressure X-ray photoelectron spectroscopy performed under polarization conditions. By analyzing the spectra of the solvent (water) and a spectator neutral molecule with numerical simulations of the electric field, we discern the shape of the electrochemical double layer profile. In addition, we determine how the electrochemical double layer changes as a function of both the electrolyte concentration and applied potential.
Electrochemical conversion of carbon dioxide (CO2) to small organic fuels (e.g. formate, methanol, ethylene, ethanol) is touted as one of the most promising approaches for solving the problems of climate change and energy security. In this study, we report the highly efficient electrochemical reduction of CO2 using cuprous oxide (Cu2O) electrodes to produce ethylene (C2H4) primarily. During CO2 electrolysis using electrodeposited Cu2O on a carbon electrode, we observe the transformation of a compact metal oxide layer to a metal oxide structure with oxygen vacant sites at the bulk region. In contrast to previous studies, our results clearly indicate that Cu2O remains at the surface of the catalyst and it efficiently catalyzes the conversion process of CO2 at low overpotential, exhibiting a high selective faradaic efficiency of over 20% towards C2H4 formation even in long-term electrolysis.
Nitrogen–carbon (N–C)
species is a potential electrocatalyst
for oxygen reduction reaction (ORR) in electrochemical energy conversion
cells, but its mechanistic origin of ORR on the N–C surface
is still unclear. We show our facile approach to the synthesis of
highly active Co-modified N–C catalyst and investigated the
origin of ORR activity of electrospun N–C species by removing
the metal with hydroxide carbon etching and acid metal leaching. Through
the detailed investigation on the origin of ORR electrocatalysis for
electrospun N–C nanofibers, we revealed that pyrrolic-N and
highly graphitized carbon structure are mainly responsible for the
enhanced ORR activity of metal-free N–C nanofiber and embedded
Co metal got involved in the creation of the pyrrolic N site.
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