Structure-activity relationships in metal organic framework derived mesoporous nitrogen-doped carbon containing atomically dispersed iron sites for CO2 electrochemical reduction
KAUST DepartmentChemical Engineering Program
KAUST Catalysis Center (KCC)
Physical Science and Engineering (PSE) Division
Online Publication Date2019-09-25
Print Publication Date2019-10
Permanent link to this recordhttp://hdl.handle.net/10754/656926
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AbstractMesoporous nitrogen-doped carbon nanoparticles with atomically dispersed iron sites (named mesoNC-Fe) are synthesized via high-temperature pyrolysis of an Fe containing ZIF-8 MOF. Hydrolysis of tetramethyl orthosilicate (TMOS) in the MOF framework prior to pyrolysis plays an essential role in maintaining a high surface area during the formation of the carbon structure, impeding the formation of iron (oxide) nanoparticles. To gain inside on the nature of the resulting atomically dispersed Fe moieties, HERFD-XANES, EXAFS and valence-to-core X-ray emission spectroscopies have been used. The experimental spectra (both XAS and XES) combined with theoretical calculations suggest that iron has a coordination sphere including a porphyrinic environment and OH/H2O moieties responsible for the high activity in CO2 electroreduction. DFT calculations demonstrate that CO formation is favored in these structures because the free energy barriers of *COOH formation are decreased and the adsorption of *H is impeded. The combination of such a unique coordination environment with a high surface area in the carbon structure of mesoNC-Fe makes more active sites accessible during catalysis and promotes CO2 electroreduction.
CitationSun, X., Wang, R., Ould-Chikh, S., Osadchii, D., Li, G., Aguilar, A., … Gascon, J. (2019). Structure-activity relationships in metal organic framework derived mesoporous nitrogen-doped carbon containing atomically dispersed iron sites for CO2 electrochemical reduction. Journal of Catalysis, 378, 320–330. doi:10.1016/j.jcat.2019.09.013
SponsorsWe thank Alma I. Olivos Suarez for help in the design of the graphical abstract. Mauro Rovezzi is kindly thanked for the extraction of the X-ray emission spectra. Guanna Li thanks the NWO veni grant (no. 016.Veni.172.034). NWO surfsara is acknowledged for providing access to the supercomputer facilities.
JournalJournal of Catalysis