Coordination engineering of cobalt phthalocyanine by functionalized carbon nanotube for efficient and highly stable carbon dioxide reduction at high current density

Coordination engineering can enhance the activity and stability of the catalyst in heterogeneous catalysis. However, the axial coordination engineering between different groups on the carbon carrier and molecular catalysts in the electrocatalytic carbon dioxide reduction reaction (CO2RR) has been studied rarely. Through coordination engineering strategy, a series of amino (NH2), hydroxyl (OH), and carboxyl (COOH) groups functionalized carbon nanotubes (CNT) immobilized cobalt phthalocyanine (CoPc) catalysts are designed. Compared with no groups, OH groups and COOH groups, NH2 groups can effectively change the coordination environment of the central metal Co, thereby significantly increasing the turnover frequency (TOF) (31.4 s(-1) at -0.6 V vs. RHE, CoPc/NH2-CNT > CoPc/OH-CNT > CoPc/COOH-CN > CoPc/CNT). In the flow cell, the CoPc/NH2-CNT catalyst has high carbon monoxide (CO) selectivity at high current density (similar to 100% at -225 mA.cm(-2), similar to 96% at -351 mA.cm(-2)). Importantly, the CoPc/NH2-CNT catalyst can operate stably for 100 h at 225 mA.cm(-2). Theoretical calculations reveal that CoPc/NH2-CNT catalyst is beneficial to the formation of *COOH and desorption of *CO, thus promoting CO2RR. This work provides an excellent platform for understanding the effect of coordination engineering on electrocatalytic performance and promotes a way to explore efficient and stable catalysts in other applications.

Automated summary

The study shows that axial coordination engineering between carbon carriers and molecular catalysts can significantly enhance the efficiency and stability of catalysts in electrocatalytic CO2 reduction reactions. Introducing NH2 groups into carbon nanotube-supported cobalt phthalocyanine catalysts can effectively increase the turnover frequency and CO selectivity.