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Jeong, Hu Young
UNIST Central Research Facilities (UCRF)
Research Interests
  • Soft material characterization such as graphene using a low kV Cs-corrected TEM
  • Insitu-TEM characterization of carbon-based materials using nanofactory STM holder for Li-ion battery application
  • Structural characterization of mesoporous materials using SEM & TEM
  • Interface analysis between various oxides and metals through Cs-corrected (S)TEM
  • Resistive switching mechanism of graphene oxide thin films for RRAM application

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Thermal Transformation of Molecular Ni2+-N-4 Sites for Enhanced CO2 Electroreduction Activity

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Title
Thermal Transformation of Molecular Ni2+-N-4 Sites for Enhanced CO2 Electroreduction Activity
Author
Sa, Young JinJung, HyejinShin, DongyupJeong, Hu YoungRinge, StefanKim, HyungjunHwang, Yun JeongJoo, Sang Hoon
Issue Date
2020-10
Publisher
AMER CHEMICAL SOC
Citation
ACS CATALYSIS, v.10, no.19, pp.10920 - 10931
Abstract
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.
URI
https://scholarworks.unist.ac.kr/handle/201301/48679
URL
https://pubs.acs.org/doi/abs/10.1021/acscatal.0c02325
DOI
10.1021/acscatal.0c02325
ISSN
2155-5435
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CHM_Journal Papers
UCRF_Journal Papers
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