jp9b11830_si_001.pdf (3.05 MB)
Understanding How Atomic Sulfur Controls the Selectivity of the Electroreduction of CO2 to Formic Acid on Metallic Cu Surfaces
journal contribution
posted on 2020-03-09, 17:38 authored by Dongyu Liu, Ya Liu, Mingtao LiElectrochemical
conversion of CO2 with renewable energy
has recently gained increasing attention for its potential to offset
its dramatic exponential increase. Sulfur (S)-modified Cu electrodes
were reported to selectively reduce CO2 into formic acid
and fully quench the original CO production on clean Cu surfaces,
yet the actual mechanism is still unsolved. To further understand
this critical issue, herein, an integrated structure–selectivity
investigation on the role of sulfur upon CO2 electroreduction
was carried out. DFT calculations in combination with relevant experimental
observations from the literature were utilized to identify the existing
forms of sulfur and their impact of the reaction selectivity of CO2 to HCOOH under realistic conditions. Interestingly, most
residual sulfur atoms were found to exist in relatively unstable forms
during the reaction, which plays a dominant role in altering the reaction
pathway by enhancing CO adsorption. In turn, these strongly adsorbed
CO stabilize the unstable sulfur, and a synergetic effect between
CO and S is proposed. These findings unravel a groundbreaking comprehensive
understanding for the rational development of highly selective CO2 reduction electrocatalysts.