Imidazole-imidazolate pair as organo-electrocatalyst for CO2 reduction on ZIF-8 material

• Published in: Applied energy 2022-10, Vol.324, p.119743, Article 119743
• Main Authors: Sassone, Daniele, Bocchini, Sergio, Fontana, Marco, Salvini, Clara, Cicero, Giancarlo, Re Fiorentin, Michele, Risplendi, Francesca, Latini, Giulio, Amin Farkhondehfal, M., Pirri, Fabrizio, Zeng, Juqin
• Format: Article
• Language: English
• Subjects: carbon dioxide; catalysts; catalytic activity; CO2 activation; computers; density functional theory; DFT; Electrochemistry; electrodes; energy; geometry; hydrogen; Imidazole; imidazoles; Lewis bases; ligands; Mechanism; Modelling-guided synthesis; Molecular catalysis; species; thermodynamics; value added; ZIF-8
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2022.119743

[Display omitted] •The submitted work is of great interest for the Journal Applied Energy due to its peculiar theme, the electrochemical CO2 reduction, and for its approach in the investigation. Indeed, a complete ab initio modelling guided the experimental synthesis and testing of a molecular electrocatalyst which shows great performances for the CO2RR.•This work elucidate the possibility to activate the CO2 through organic molecules and, moreover, shows the feasibility of this approach to be completely integrated inside a TRL 3–4 electrolysis cell. The electrochemical reduction of CO2 to value-added products is hindered by its thermodynamic stability and by the large energy required to chemically activate the molecule. With this respect, forcing CO2 in a non-linear geometry would induce an internal electron charge rearrangement which would facilitate further electrochemical transformations. In this work, we achieved this goal through the design of a dual function electro-organocatalyst, which exploits the ability of the imidazolate (Im-) lone pair to bind CO2 via nucleophilic attack and then electrochemically reduce it. To give structural stability to the Im- based catalyst, the imidazoles species are incorporated into a solid structure, namely ZIF-8. Once activated by the organic Im- ligand, CO2 is electrochemically reduced to CO when a bias is applied to ZIF-8. The catalyst proposed in our study was first devised by computer aided design based on Density functional Theory simulations and then realized in laboratory. Our results demonstrate that ZIF-8 supported on conductive CNTs presents surface Im- active sites which convert CO2 into CO with a high faradaic efficiency (70.4 %) at −1.2 V vs reversible hydrogen electrode, by combining chemical activation with electrochemical catalysis.