Tuning Electronic Structures of Covalent Co Porphyrin Polymers for Electrocatalytic CO <sub>2</sub> Reduction in Aqueous Solutions
Yabo Wang, Xuepeng Zhang, Haitao Lei, Kai Guo, Gelun Xu, Lisi Xie, Xialiang Li, Wei Zhang, Ulf‐Peter Apfel, Rui Cao
Abstract
Improving the selectivity of the electrocatalytic CO2 reduction reaction (CO2RR) over hydrogen evolution in aqueous solutions is required but challenging because the two reactions occur at close thermodynamic potentials and compete with each other. Herein, we report on the selective CO2RR in aqueous solutions utilizing covalent Co porphyrin polymers with fine-tuned electronic structures. CoP@CNT, CoP-Ph@CNT, and CoP-F@CNT, synthesized by Hay-coupling Co porphyrin monomers on carbon nanotubes, showed higher activity and durability than the respective monomers for CO2RR. By tuning the electronic structures, the CO2RR selectivity of CoP@CNT (FECO > 95%) and CoP-Ph@CNT (FECO > 80%) was significantly improved compared with CoP-F@CNT (FECO < 20%). Remarkably, CoP@CNT catalyzed CO2RR with FECO > 95% in aqueous solutions in a wide overpotential range of 460–760 mV. Theoretical studies suggest that the electron-rich CoI centers of CoP and CoP-Ph can favorably bind CO2, leading to improved CO2RR selectivity.