Rational Design of Polymers for Selective CO₂ Reduction Catalysis

Abstract

A series of copolymers comprising a terpyridine ligand and various functional groups were synthesized toward integrating a Co‐based molecular CO2 reduction catalyst. Using porous metal oxide electrodes designed to host macromolecules, the Co‐coordinated polymers were readily immobilized via phosphonate anchoring groups. Within the polymeric matrix, the outer coordination sphere of the Co terpyridine catalyst was engineered using hydrophobic functional moieties to improve CO2 reduction selectivity in the presence of water. Electrochemical and photoelectrochemical CO2 reduction were demonstrated with the polymer‐immobilized hybrid cathodes, with a CO:H2 product ratio of up to 6:1 compared to 2:1 for a corresponding “monomeric” Co terpyridine catalyst. This versatile platform of polymer design demonstrates promise in controlling the outer‐sphere environment of synthetic molecular catalysts, analogous to CO2 reductases.

Metal‐Terpyridine Complexes in Catalytic Application – A Spotlight on the Last Decade

“…A variety of electrode materials were combined with the IO‐TiO 2 |metallopolymer hybrid material and tested with respect to the production of CO and H 2 from CO 2 ‐purged aq. acetonitrile . From the systems under investigation, the photocathode with the composition Si|IO‐TiO 2 |metallopolymer yielded the highest selectivity with respect to the obtained CO‐to‐H 2 , i. e ., a product selectivity for CO of ca .…”

“…In order to further improve the photoelectrocatalytic activity of the electrodes, the same authors prepared the copolymers 31 (Figure a) by free‐radical polymerization and subsequently loaded them with Co(II) . The resultant partially cross‐linked metallopolymers were immobilized onto a mesoporous inverse opal TiO 2 (IO‐TiO 2 ) via their phosphonate moieties.…”

“… (a) Schematic representation of the copolymers 31 . (b) Schematic representation of the copolymers 31 , complexed by Co(II) ions .…”

“… (a) Schematic representation of the copolymers 31 . (b) Schematic representation of the copolymers 31 , complexed by Co(II) ions . (c) SEM image of the IO‐TiO 2 and schematic representation of metal‐loaded 31 within in the porous scaffold .…”

“…(b) Schematic representation of the copolymers 31 , complexed by Co(II) ions . (c) SEM image of the IO‐TiO 2 and schematic representation of metal‐loaded 31 within in the porous scaffold . Figure reproduced with kind permission; © 2019 Wiley‐VCH.…”