Selective Etching of Nitrogen-Doped Carbon by Steam for Enhanced Electrochemical CO2 Reduction

5 years ago

Selective Etching of Nitrogen-Doped Carbon by Steam for Enhanced Electrochemical CO2 Reduction

Gengfeng Zheng, Huisheng Peng, Lijuan Zhang, Xiaoqi Cui, Zhiyong Pan

Nitrogen-doped carbon structures have recently been demonstrated as a promising candidate for electrocatalytic CO2 reduction, while in the meantime the pyridinic and graphitic nitrogen atoms also present high activities for electroreduction of water. Here, an etching strategy that uses hot water steam to preferentially bind to pyridinic and graphitic nitrogen atoms and subsequently etch them in carbon frameworks is reported. As a result, pyrrolic nitrogen atoms with low water affinity are retained after the steam etching, with a much increased level of among all nitrogen species from 22.1 to 55.9%. The steam-etched nitrogen-doped carbon catalyst enables excellent electrocatalytic CO2 reduction performance but low hydrogen evolution reaction activity, suggesting a new approach for tuning electrocatalyst activity. A steam-etching approach is developed to tune the configurations of nitrogen dopants in carbon frameworks. The carbon atoms around pyridinic and graphitic N are more susceptible to steam etching because of their stronger binding capability to water molecules. The obtained pyrrolic-N-rich catalyst shows much-enhanced CO2 reduction catalytic activity and hydrogen evolution reaction (HER) suppression.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/aenm.201701456