In-situ Electropolymerized Three-Dimensional Microporous Cobalt-Porphyrin Nanofilm for Highly Effective Molecular Electrocatalytic Reduction of Carbon Dioxide.

Electrocatalytic CO 2 reduction reaction (CO 2 RR) based on molecular catalysts, e.g., cobalt porphyrin, is a promising approach to enhance carbon cycle and mitigate climate crisis. However, the electrocatalytic performance and accurate evaluations remains problems because of either the low loading amount or the low utilization rate of the electroactive CoN 4 sites. W e herein synthesized a monomer, cobalt(II)-5,10,15,20-tetrakis(3,5-di(thiophen-2-yl)phenyl)porphyrin (CoP), electropolymerized it onto the crosslinked carbon nanotubes (CNTs) networks, affording a molecular electrocatalyst of three-dimensional (3D) microporous nanofilm (EP-CoP, 2∼3 nm thickness) with highly dispersed CoN 4 sites. The new electrocatalyst shortens the electron transfer pathway, accelerates the redox kinetics of CoN 4 sites and improves the durability in the electrocatalytic CO 2 RR. From the intrinsic redox behavior of CoN 4 sites, the effective utilization rate is obtained as 13.1%, much higher than that of the monomer assembled electrode (5.8%), and the durability is also promoted dramatically (> 40 h) in a H-type cell. In a commercial flow cell, EP-CoP can achieve a faradic efficiency for CO (FE CO ) over 92% at an overpotential of 160 mV. At a higher overpotential of 620 mV, the working current density can reach 310 mA cm -2 with a high FE CO of 98.6%, representing the best performance for electrodeposited molecular porphyrin electrocatalysts. This article is protected by copyright. All rights reserved.