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Hollow Carbon Nanopolyhedra for Enhanced Electrocatalysis via Confined Hierarchical Porosity
Author(s) -
Song Xiaokai,
Guo Linli,
Liao Xuemei,
Liu Jian,
Sun Jianhua,
Li Xiaopeng
Publication year - 2017
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201700238
Subject(s) - materials science , carbon fibers , porosity , electrocatalyst , chemical engineering , electrolyte , metal organic framework , pyrolysis , fabrication , nanotechnology , methanol , electrochemistry , electrode , chemistry , composite material , organic chemistry , composite number , medicine , alternative medicine , adsorption , pathology , engineering
A novel strategy for the fabrication of hollow Co and N‐codoped carbon nanopolyhedra (H‐CoNC) from metal–organic framework (MOF) using in situ evaporation of ZnO nanosphere templates is proposed. The excess Zn supply during the pyrolysis process is found beneficial in terms of high nitrogen (≈9.75 at%), relatively homogenous CoN bonding, and the electrochemically accessible hierarchical porous system. Compared with other reported “solid” CoNC of identical surface areas, the newly developed H‐CoNC shows enhanced kinetic current in 0.1 m KOH electrolyte and elevated oxygen reduction reaction (ORR) performance in 6 m KOH. The latter exceeds results obtained with the benchmark 20 wt% Pt/C, which is related to the strong confinement of O 2 molecules in the H‐CoNC hierarchical porous system. Furthermore, the H‐CoNC displays great tolerance toward the methanol crossover and KSCN poisoning. Finally, the assembled Zn–air batteries with H‐CoNC yield a record open circuit potential (1.59 V vs Zn, stabilized at 1.52 V), high power density (331.0 mW cm −2 ), and promising rate performance. This work provides a new guideline for the design of MOF‐derived carbon materials, as well as novel insights into spatial confinement effect toward the ORR activity.