Tuning Electronic Structures of Covalent Co Porphyrin Polymers for Electrocatalytic CO ₂ Reduction in Aqueous Solutions

Abstract

Improving the selectivity of electrocatalytic CO 2 reduction reaction (CO 2 RR) over hydrogen evolution in aqueous solutions is required but challenging because the two reactions occur at close thermodynamic potentials and compete with each other. We herein report on the selective CO 2 RR 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 respective monomers for CO 2 RR. By tuning the electronic structures, the CO 2 RR selectivity of CoP@CNT (FE CO > 95%) and CoP-Ph@CNT (FE CO > 80%) was significantly improved compared to CoP-F@CNT (FE CO < 20%). Remarkably, CoP@CNT catalyzed CO 2 RR with FE CO > 95% in aqueous solutions in a wide overpotential range of 460-760 mV. Theoretical studies suggested that electron-rich Co I centers of CoP and CoP-Ph can favorably bind CO 2 , leading to improved CO 2 RR selectivity.

Enzyme‐Inspired Microenvironment Engineering of a Single‐Molecular Heterojunction for Promoting Concerted Electrochemical CO2 Reduction

“…[1][2][3] Crucially, how to design and construct efficient electrocatalysts under industrial-level operation has important strategic significance. [4,5] Significant efforts in this fascinating field have been devoted to exploring electrocatalytic materials with a high performance for CO 2 conversion, such as noble metals, [6][7][8][9][10] carbon-based singleatoms, [11][12][13][14] metal-organic frameworks/ covalent organic frameworks (MOFs/ COFs), [15][16][17][18][19][20] dispersed molecules, [21][22][23][24][25][26][27] etc. Among these electrocatalytic materials, particularly the π-conjugated metallomacrocyclic molecules (e.g., phthalocyanines and porphyrins) heterogenized at the single-molecular level, namely single-molecular heterojunction (SMH) electrocatalysts, offer an ideal platform for eCO 2 RR and reaction mechanism studies due to the definite coordination structures of metal centers, relatively uncomplicated synthetic procedures and flexible design assembling.…”

Synthesis and Design of Hybrid Metalloporphyrin Polymers Based on Palladium (II) and Copper (II) Cations and Axial Complexes of Pyridyl-Substituted Sn(IV)Porphyrins with Octopamine

“…Coordination polymers based on metal complexes of tetrapyrrole macrocyclic compounds represent a special group of self-organized systems that combine their structural fragments through non-covalent interactions [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Such interactions are reversible and easily controlled by various external influences.…”

“…Therefore, the coordination self-assembly is a convenient tool to create stable and controllable architectures by the self-organization of metal and organic components with electronic and geometric complementarity. Different functional substituents, the type of organic fragments binding, the metal nature, and the length of the linking fragments provide a variety of framework structure types and areas of their potential application [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. The construction of supramolecular porphyrin scaffolds is still little studied, but it is undoubtedly an urgent scientific problem, the solution of which will to get closer to understanding the life processes of nature.…”

Electrocatalytic CO2 Reduction to Syngas and HCOOH by Homogeneous Fc‐NAP2

“…Further, they have synthesized a Fe porphyrin N18 C6‐FeP bearing a tethered 1‐aza‐18‐crown‐6‐ether (N18 C6) group, the Fe sites occupies the second coordination sphere. The N18 C6‐FeP is more active than FeP for electrocatalytic CO 2 RR [13–15] . David et al .…”