Open AccessBifunctional Nitrogen and Cobalt Codoped Hollow Carbon for Electrochemical Syngas Production
Author(s) -
Song Xiaokai,
Zhang Hao,
Yang Yuqi,
Zhang Bin,
Zuo Ming,
Cao Xin,
Sun Jianhua,
Lin Chao,
Li Xiaopeng,
Jiang Zheng
Publication year - 2018
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201800177
Subject(s) - electrocatalyst , bifunctional , electrochemistry , imidazolate , syngas , zeolitic imidazolate framework , catalysis , metal organic framework , carbon fibers , materials science , cobalt , chemical engineering , chemistry , inorganic chemistry , electrode , organic chemistry , adsorption , composite material , composite number , engineering
Electrochemical conversion of CO 2 and H 2 O into syngas is an attractive route to utilize green electricity. A competitive system economy demands development of cost‐effective electrocatalyst with dual active sites for CO 2 reduction reaction (CO 2 RR) and hydrogen evolution reaction (HER). Here, a single atom electrocatalyst derived from a metal–organic framework is proposed, in which Co single atoms and N functional groups function as atomic CO 2 RR and HER active sites, respectively. The synthesis method is based on pyrolysis of ZnO@ZIF (zeolitic imidazolate framework). The excess in situ Zn evaporation effectively prevents Co single atoms (≈3.4 wt%) from aggregation and maintains appropriate Co/N ratio. The as‐prepared electrocatalyst is featured with high graphitic degree of carbon support for rapid electron transport and sponge‐like thin carbon shells with hierarchical pore system for facilitating active site exposure and mass transport. Therefore, the electrocatalyst exhibits a nearly 100% Faradic efficiency and a high formation rate of ≈425 mmol g −1 h −1 at 1.0 V with the gaseous product ratio (CO/H 2 ) approximating ideal 1/2. With the assistance of an extensive material characterization and density functional theory (DFT) calculations, it is identified that Co single atoms are uniformly coordinated in the form of Co–C 2 N 2 moieties, and act as the major catalytic sites for CO 2 reduction.