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/NH ₂-CNT catalyst has high carbon monoxide (CO) selectivity at high current density (~ 100% at −225 mA·cm⁻², ~ 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.