Enhancing CO₂ Reduction Efficiency on Cobalt Phthalocyanine via Axial Ligation

Abstract

Electrochemical reduction of carbon dioxide (CO 2 RR) to valueadded products is a promising strategy to alleviate the greenhouse gas effect. Molecular catalysts, such as cobalt (II) phthalocyanine (CoPc), are known to be efficient electrocatalysts that are capable of converting CO 2 into carbon monoxide (CO). Herein, we report an axial modification strategy to enhance CoPc's CO 2 RR performance. After coordinating with axial ligands, the electron density of Co was depleted via πbackbonding. This π-backbonding weakened the Co-CO bond, resulting in rapid desorption of CO. Also, the presence axial ligands elevated the Co dz 2 orbital energy, resulting in a significantly enhanced CO selectivity, evidenced by an increased faradaic efficiency (FE) from 82 % (CoPc) to 91 % and 94 % with the presence of pyridine (CoPc-py) and imidizal ligands (CoPcim), respectively, at À 0.82 V vs. RHE. Density functional theory calculations reveal that axial ligation of CoPc can reduce the energy barrier for CO 2 activation and facilitate the formation of *COOH.

Electrospun Nanofiber Composite Utilized as an Electrocatalyst for the Detection of Acetaminophen in Multifarious Water Samples

“…The blue shift in the Q-band is associated with the decreasing electron density of the cobalt center due to the donation from the d-orbitals of Co to a π* orbital of PANI. 42 Additionally, common broad charge-transfer (CT) bands at 619 nm in the electronic spectra of free PANI and its conjugate were found close to the CT-band at 610 nm of the CoPc-fur. The PANI bands between 320 and 390 nm are due to π–π* electrical transitions (benzenoid segments) associated with the structural units of PANI chains.…”

“…The combination of PANI and CoPc-fur resulted in a blue shift in the CoPc Q-band and a red shift in its Soret band. The blue shift in the Q-band is associated with the decreasing electron density of the cobalt center due to the donation from the d-orbitals of Co to a π* orbital of PANI . Additionally, common broad charge-transfer (CT) bands at 619 nm in the electronic spectra of free PANI and its conjugate were found close to the CT-band at 610 nm of the CoPc-fur.…”

Simple Preparation and Characterization of Hybrid Cobalt Phthalocyanine on Multiwalled Carbon Nanotube Electrodes

“…Based on this finding, we conclude that solvent-ligated CoPc is present in the hybrid electrodes, despite rigorous drying. Axial ligation has been found to influence the redox properties of metallophthalocyanines, as well as the CO 2 reduction activity and mechanism of CoPc, − though this has only been explored for pyridine-like donor ligands and not the solvents used in this work.…”

Molecular Enhancement of Direct Electrolysis of Dilute CO2

“…CoPc, a molecular catalyst selective for CO production from CO 2 electrolysis, − was first used as a model catalyst. To improve the dispersion and electric conductivity of CoPc molecules, commercial CoPc powder was mixed with carbon black nanoparticles to form a catalyst ink for preparing a bare CoPc gas diffusion electrode.…”