Metal-ligand catalysts for selective promotion of electrochemical CO
The electrochemical carbon dioxide reduction reaction (CO 2 RR) provides opportunities to synthesize value-added products from this greenhouse gas in a sustainable manner. Efficient catalysts for this reaction are provided that selectively drive CO 2 reduction over the thermodynamic and kinetically competitive hydrogen evolution reaction (HER) in organic or aqueous electrolytes. The catalysts are metal-polypyridyl coordination complexes of a redox non-innocent terpyridine-based pentapyridine ligand and a first-row transition metal. The metal-ligand cooperativity in [Fe(tpyPY2Me)] 2+ drives the electrochemical reduction of CO 2 to CO at low overpotentials with high selectivity for CO 2 RR (>90%).
1. A metal coordination complex catalyst, comprising:
(a) a metal; and
(b) a tpyPY2Me ligand represented by formula (1)
wherein each substituent lettered A to S of said ligand is independently selected from the group of substituents consisting of H, R, a halide, CF 3 , OR, NR 2 , and SiR 3 , where R is an alkyl group or an aryl group.
2. The catalyst of claim 1 , further comprising a counter ion selected from the group consisting of Cl, Br, I, PF 6 , CF 3 SO 3 , and [(3,5-(CF 3 ) 2 C 6 H 3 ) 4 B].
3. The catalyst of claim 1 , wherein said metal comprises Fe forming an iron(II) complex [Fe(tpyPY2Me)] 2+ .
4. The catalyst of claim 1 , wherein each substituent lettered A to S comprises a hydrogen atom.
5. The catalyst of claim 1 , wherein said substituents lettered A to S are independently selected from the group of substituents consisting of H, R, OR, NR 2 , and SiR 3 , where R is an alkyl group selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, pentyl, hexyl and cyclohexyl groups.
6. The catalyst of claim 1 , wherein said substituents lettered A to S are independently substituents consisting of H, R, OR, NR 2 , and SiR 3 , where R is an aryl group selected from the group consisting of phenyl, naphthyl, pyridinyl, indolyl and 2-methyl-phenyl groups.