Enhancement of electrocatalytic abilities toward CO2 reduction by tethering redox-active metal complexes to the active site. Issue 38 (2nd September 2021)

• Record Type: Journal Article
• Authors: Md. Ahsan, Habib; Breedlove, Brian K.; Cosquer, Goulven; Yamashita, Masahiro
• Is Part Of: Dalton transactions. Volume 50:Issue 38(2021)
• Page Start: 13368
• Page End: 13373
• Publication Date: 2021-09-02
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt02318g
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Redox-active metal complexes were tethered with a modified Ni(ii )cyclen catalytically active site and reduce prior to the catalytically active site and increase the electron density to enhance electrocatalytic abilities towards CO2 reduction. Abstract : Tethering metal complexes, like [Ru(bpy)2 Cl2 ] (bpy = 2, 2′-bipyridine), which are redox-active at low reduction potentials and have the ability to transfer electrons to another complex, to a [Ni(cyclen)] 2+ electrocatalyst enhanced the reduction of CO2 to CO at low overpotentials. The [Ni(cyclen)] 2+ electrocatalyst was modified by tethering redox-active metal complexes via 4-methylpyridyl linkers. The redox-active metal complexes were reduced after CO2 bound to the active site. In controlled potential electrolysis (CPE) experiments in 95 : 5 (v/v) CH3 CN/H2 O, [{([Ru]pic)4 cyclen}NiCl] 5+ ([Ru] + = {Ru(bpy)2 Cl} + ; pic = 4-methylpyridyl) could be used to reduce CO2 into CO at a turnover frequency (TOF) of 708 s −1 with a faradaic efficiency (FE) of 80% at an onset potential of −1.60 V vs . NHE. At the same time, this electrocatalyst was active at an onset potential of −1.25 V vs . NHE, which is the reduction potential of one of the bpy ligands of the [Ru] + moieties, with FE = 84% and TOF = 178 s −1 . When the electrocatalysis was performed using [bn4 cyclenNiCl]Cl (bn = benzyl) without tethered redox-active metal complexes, the TOF value was determined to be 8 s −1 with FE = 77% at an onset potential of −1.45 V vs . NHE. The results show that tethering redox-active metal complexes significantly improves the electrocatalytic activities by lowering the potential needed to reduce CO2 .