Covalent triazine framework modified with coordinatively-unsaturated Co or Ni atoms for CO2 electrochemical reduction

Panpan Su; Kazuyuki Iwase; Takashi Harada; Kazuhide Kamiya; Shuji Nakanishi

doi:10.1039/c8sc00604k

Covalent triazine framework modified with coordinatively-unsaturated Co or Ni atoms for CO₂ electrochemical reduction

Chem Sci. 2018 Mar 19;9(16):3941-3947. doi: 10.1039/c8sc00604k. eCollection 2018 Apr 28.

Authors

Panpan Su¹, Kazuyuki Iwase², Takashi Harada¹, Kazuhide Kamiya^{1

3

4}, Shuji Nakanishi^{1

3}

Affiliations

¹ Research Center for Solar Energy Chemistry , Osaka University , 1-3 Machikaneyama, Toyonaka , Osaka 560-8531 , Japan . Email: kamiya@chem.es.osaka-u.ac.jp ; Email: nakanishi@chem.es.osaka-u.ac.jp.
² Department of Applied Chemistry , The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku , Tokyo 113-8656 , Japan.
³ Graduate School of Engineering Science , Osaka University , 1-3 Machikaneyama, Toyonaka , Osaka 560-8531 , Japan.
⁴ Japan Science and Technology Agency (JST) , PRESTO , 4-1-8 Honcho , Kawaguchi , Saitama 332-0012 , Japan.

Abstract

The electrochemical reduction of carbon dioxide (CO₂) has attracted considerable attention as a means of maintaining the carbon cycle. This process still suffers from poor performance, including low faradaic efficiencies and high overpotential. Herein, we attempted to use coordination number as a control parameter to improve the electrocatalytic performance of metal species that have previously been thought to have no CO₂ reduction activity. Covalent triazine frameworks (CTF) modified with coordinatively-unsaturated 3d metal atoms (Co, Ni or Cu) were developed for efficient electroreduction of CO₂. Co-CTF and Ni-CTF materials effectively reduced CO₂ to CO from -0.5 V versus RHE. The faradaic efficiency of the Ni-CTF during CO formation reached 90% at -0.8 V versus RHE. The performance of Ni-CTF is much higher than that of the corresponding metal-porphyrin (using tetraphenylporphyrin; TPP). First principles calculations demonstrated that the intermediate species (adsorbed COOH) was stabilized on the metal atoms in the CTF due to the low-coordination structure of this support. Thus, the free energy barriers for the formation of adsorbed COOH on the metal atoms in the CTF supports were lower than those on the TPP supports.