Thermal Transformation of Molecular Ni2+-N-4 Sites for Enhanced CO2 Electroreduction Activity
Cited 0 times inCited 0 times in
- Thermal Transformation of Molecular Ni2+-N-4 Sites for Enhanced CO2 Electroreduction Activity
- Sa, Young Jin; Jung, Hyejin; Shin, Dongyup; Jeong, Hu Young; Ringe, Stefan; Kim, Hyungjun; Hwang, Yun Jeong; Joo, Sang Hoon
- Issue Date
- AMER CHEMICAL SOC
- ACS CATALYSIS, v.10, no.19, pp.10920 - 10931
- Atomically dispersed nickel sites complexed on nitrogen-doped carbon (Ni-N/C) have demonstrated considerable activity for the selective electrochemical carbon dioxide reduction reaction (CO2RR) to CO. However, the high-temperature treatment typically involved during the activation of Ni-N/C catalysts makes the origin of the high activity elusive. In this work, Ni(II) phthalocyanine molecules grafted on carbon nanotube (NiPc/CNT) and heat-treated NiPc/CNT (H-NiPc/CNT) are exploited as model catalysts to investigate the impact of thermal activation on the structure of active sites and CO2RR activity. H-NiPc/CNT exhibits a similar to 4.7-fold higher turnover frequency for CO2RR to CO in comparison to NiPc/CNT. Extended X-ray absorption fine structure analysis and density functional theory (DFT) calculations reveal that the heat treatment transforms the molecular Ni2+-N-4 sites of NiPc into Ni+-N3V (V: vacancy) and Ni+-N-3 sites incorporated in the graphene lattice that concomitantly involves breakage of Ni-N bonding, shrinkage in the Ni-N-C local structure, and decrease in the oxidation state of the Ni center from +2 to +1. DFT calculations combined with microkinetic modeling suggest that the Ni-N3V site appears to be responsible for the high CO2RR activity because of its lower barrier for the formation of * COOH intermediate and optimum *CO binding energy. In situ/operando X-ray absorption spectroscopy analyses further corroborate the importance of reduced Ni+ species in boosting the CO2RR activity.
- Appears in Collections:
- CHM_Journal Papers
- Files in This Item:
- There are no files associated with this item.
can give you direct access to the published full text of this article. (UNISTARs only)
Show full item record
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.