Nitrogen-rich carbon nitride inducing electron delocalization of Co-N4 site to enhance electrocatalytic carbon dioxide reduction

• Published in: Applied catalysis. B, Environmental Environmental, 2023-04, Vol.323, p.122199, Article 122199
• Main Authors: Masana, Jofrey Jackson, Xiao, Jiayong, Zhang, Hui, Lu, Xiaoying, Qiu, Ming, Yu, Ying
• Format: Article
• Language: English
• Subjects: Co-N5 catalytic site; Cobalt phthalocyanine; Electrochemical reduction of CO2; Electron delocalization; Nitrogen-rich carbon nitride
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.122199

Cobalt phthalocyanine (CoPc) is an appealing electrocatalyst for CO2 reduction. However, its catalytic performance is limited by instability and low conductivity. Herein, theoretical calculations reveal that nitrogen-rich carbon nitride, as a promising Supporting material, can help to tune the electronic structure of CoPc and then enhance its stability and conductivity by inducing electron delocalization of Co-N4 sites for the formation of Co-N5, achieving a superior electrochemical reduction of CO2. Inspired by this prediction, we prepared nitrogen-rich carbon nitride that coordinated with Co-N4 through axial N coordination under 400ºC, forming an atomically dispersed Co-N5 catalytic site. The synthesized catalyst demonstrates excellent performance in CO2 conversion to CO with >99 % selectivity at a current density of − 5.3 mA cm-2, which can remain for 40 h. These findings provide a strategy for regulating catalytic sites and shed light on expanding the applications of low-cost carbon nitride materials at mild heat-treatment temperatures. [Display omitted] •Catalytic site of cobalt phthalocyanine (CoPc) can be regulated with nitrogen-rich carbon nitride at mild-heat treatment temperature of 400ºC•Nitrogen-rich carbon nitride induces electron delocalization of Co-N4 site for the formation of Co-N5, thus modulates CoPc intrinsic electronic structure and, thereby d-band center, which enhances the conductivity and CO2 reduction performance.•CoPc and nitrogen-rich carbon nitride coordination enhance CO2 activation, effectively decrease the energy barrier of intermediate *COOH and optimize desorption of CO as well.