Electrochemical Generation of Catalytically Active Edge Sites in C 2 N‐Type Carbon Materials for Artificial Nitrogen Fixation

GND
1269984292
Affiliation
Center for Energy and Environmental Chemistry Jena (CEEC Jena) Institute for Technical Chemistry and Environmental Chemistry Friedrich‐Schiller‐University Jena Philosophenweg 7a 07743 Jena Germany
Zhang, Wuyong;
Affiliation
Department of Chemistry University of California Riverside CA 92521 USA
Zhan, Shaoqi;
Affiliation
Max Planck Institute of Colloids and Interfaces Department of Colloid Chemistry Am Mühlenberg 1 14476 Potsdam Germany
Qin, Qing;
Affiliation
Max Planck Institute of Colloids and Interfaces Department of Colloid Chemistry Am Mühlenberg 1 14476 Potsdam Germany
Heil, Tobias;
Affiliation
Hefei National Laboratory for Physical Sciences at the Microscale Collaborative Innovation Center of Chemistry for Energy Materials School of Chemistry and Materials Science University of Science and Technology of China Hefei Anhui 230026 P. R. China
Liu, Xiyu;
Affiliation
Max Planck Institute of Colloids and Interfaces Department of Colloid Chemistry Am Mühlenberg 1 14476 Potsdam Germany
Hwang, Jinyeon;
Affiliation
Surface Science Laboratory Department of Materials and Earth Sciences Technical University of Darmstadt Otto‐Berndt‐Strasse 3 64287 Darmstadt Germany
Ferber, Thimo H.;
Affiliation
Surface Science Laboratory Department of Materials and Earth Sciences Technical University of Darmstadt Otto‐Berndt‐Strasse 3 64287 Darmstadt Germany
Hofmann, Jan P.;
GND
1070230448
ORCID
0000-0003-2377-1214
Affiliation
Center for Energy and Environmental Chemistry Jena (CEEC Jena) Institute for Technical Chemistry and Environmental Chemistry Friedrich‐Schiller‐University Jena Philosophenweg 7a 07743 Jena Germany
Oschatz, Martin

The electrochemical nitrogen reduction reaction (NRR) to ammonia (NH 3 ) is a potentially carbon‐neutral and decentralized supplement to the established Haber–Bosch process. Catalytic activation of the highly stable dinitrogen molecules remains a great challenge. Especially metal‐free nitrogen‐doped carbon catalysts do not often reach the desired selectivity and ammonia production rates due to their low concentration of NRR active sites and possible instability of heteroatoms under electrochemical potential, which can even contribute to false positive results. In this context, the electrochemical activation of nitrogen‐doped carbon electrocatalysts is an attractive, but not yet established method to create NRR catalytic sites. Herein, a metal‐free C 2 N material (HAT‐700) is electrochemically etched prior to application in NRR to form active edge‐sites originating from the removal of terminal nitrile groups. Resulting activated metal‐free HAT‐700‐A shows remarkable catalytic activity in electrochemical nitrogen fixation with a maximum Faradaic efficiency of 11.4% and NH 3 yield of 5.86 µg mg −1 cat h −1 . Experimental results and theoretical calculations are combined, and it is proposed that carbon radicals formed during activation together with adjacent pyridinic nitrogen atoms play a crucial role in nitrogen adsorption and activation. The results demonstrate the possibility to create catalytically active sites on purpose by etching labile functional groups prior to NRR.

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