CO2 Overall Splitting by a Bifunctional Metal‐Free Electrocatalyst

Photo/electrochemical CO2 splitting is impeded by the low cost‐effective catalysts for key reactions: CO2 reduction (CDRR) and water oxidation. A porous silicon and nitrogen co‐doped carbon (SiNC) nanomaterial by a facile pyrolyzation was developed as a metal‐free bifunctional electrocatalyst. CO2‐t...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2018-10, Vol.57 (40), p.13135-13139
Main Authors: Ghausi, Muhammad Arsalan, Xie, Jiafang, Li, Qiaohong, Wang, Xueyuan, Yang, Rui, Wu, Maoxiang, Wang, Yaobing, Dai, Liming
Format: Article
Language:English
Subjects:
bifunctional systems
Carbon dioxide
Catalysts
Chemical evolution
CO2 reduction
electrocatalysis
Electrochemistry
Electronic structure
Energy efficiency
Free energy
Intermediates
metal-free electrodes
Metals
Nanomaterials
Nitrogen
Organic chemistry
Oxidation
Photosynthesis
Photovoltaics
Porous silicon
Splitting
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Summary:Photo/electrochemical CO2 splitting is impeded by the low cost‐effective catalysts for key reactions: CO2 reduction (CDRR) and water oxidation. A porous silicon and nitrogen co‐doped carbon (SiNC) nanomaterial by a facile pyrolyzation was developed as a metal‐free bifunctional electrocatalyst. CO2‐to‐CO and oxygen evolution (OER) partial current density under neutral conditions were enhanced by two orders of magnitude in the Tafel regime on SiNC relative to single‐doped comparisons beyond their specific area gap. The photovoltaic‐driven CO2 splitting device with SiNC electrodes imitating photosynthesis yielded an overall solar‐to‐chemical efficiency of advanced 12.5 % (by multiplying energy efficiency of CO2 splitting cell and photovoltaic device) at only 650 mV overpotential. Mechanism studies suggested the elastic electron structure of −Si(O)−C−N− unit in SiNC as the highly active site for CDRR and OER simultaneously by lowering the free energy of CDRR and OER intermediates adsorption. Silicon and nitrogen co‐doped porous carbon synthesized by pyrolysis exhibited CO2 reduction and O2 evolution that was enhanced by two orders of magnitude. This may be due to the elastic electron structure that enabled −Si(O)−C−N− active‐site lower free energy of intermediates adsorption, leading to photovoltaic‐driven neutral CO2 overall splitting on a metal‐free bifunctional electrocatalyst with 12.5 % solar‐to‐chemical efficiency.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201807571