On the Role of Sulfur for the Selective Electrochemical Reduction of CO2 to Formate on CuS x Catalysts.
Yilin DengYun HuangDan RenAlbertus Denny HandokoZhi Wei SehPussana HirunsitBoon Siang YeoPublished in: ACS applied materials & interfaces (2018)
The efficient electroreduction of CO2 has received significant attention as it is one of the crucial means to develop a closed-loop anthropogenic carbon cycle. Here, we describe the mechanistic workings of an electrochemically deposited CuS x catalyst that can reduce CO2 to formate with a Faradaic efficiency (FEHCOO-) of 75% and geometric current density ( jHCOO-) of -9.0 mA/cm2 at -0.9 V versus the reversible hydrogen electrode. At this potential, the formation of other CO2 reduction products such as hydrocarbons and CO was notably suppressed (total FE < 4%). The formate intermediate (HCOO*) was identified by operando Raman spectroscopy with isotopic labeling. A combination of electrochemical and materials characterization techniques revealed that the high selectivity toward formate production can be attributed to the effect of S dopants on the Cu catalyst, rather than surface morphology. Density functional theory calculations showed that the presence of sulfur weakens the HCOO* and *COOH adsorption energies, such that the formation of *COOH toward CO is suppressed, while the formation of HCOO* toward formate is favored.
Keyphrases
- density functional theory
- ionic liquid
- metal organic framework
- raman spectroscopy
- molecular dynamics
- highly efficient
- gold nanoparticles
- room temperature
- visible light
- aqueous solution
- reduced graphene oxide
- working memory
- label free
- carbon dioxide
- single cell
- risk assessment
- mass spectrometry
- molecular dynamics simulations
- carbon nanotubes
- climate change
- human health