Electrocatalytic hydrogen production and carbon dioxide conversion by earth abundant transition metal complexes of the Schiff base ligand: (E)-1-((2-dimethylamino)-propylimino)methyl)naphthalene-2-ol. (15th November 2020)

• Record Type: Journal Article
• Authors: Sengupta, Swaraj; Khan, Sahanwaj; Naath Mongal, Binitendra; Lewis, William; Fleck, Michel; Chattopadhyay, Shyamal K.; Naskar, Subhendu
• Is Part Of: Polyhedron. Volume 191(2020)
• Publication Date: 2020-11-15
• Subjects: Transition metal complexes -- Electrocatalysis -- Hydrogen production -- CO2 conversion -- HPLC; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2020.114798
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: One Co(III) complex (1) and one Ni(II) complex (2) of the Schiff base ligand: (E)-1-((2-(dimethylamino)ethylimino)methyl)naphthalene-2-ol successfully catalyze the reduction of acid and carbon dioxide, respectively. Complex 1 electrocatalyses acid reduction to hydrogen at a relatively high potential (−0.7 V) with a turnover frequency of 7.05 s −1 with a 10:1 ratio of acid to catalyst. Complex 2 catalyses the reduction of carbon dioxide electrochemically to form oxalic acid. The rate of oxalic acid formation is 1.3495 × 10 −7 M/min. with a kcat value of 58.03 s −1 . Highlights: Co(III) and Ni(II) complexes of the Schiff base ligand are reported. The Co(III) complex acts as electrocatalyst for the reduction of acid to hydrogen. The Ni(II) complex behaves as electrocatalyst for reduction of CO2 to oxalic acid. Abstract: The present work describes an electrocatalytic study for the conversion of carbon dioxide to environmentally benign and industrially important products, as well as the production of hydrogen (green energy) from acids using earth abundant transition metal complexes as catalysts. One cobalt and one nickel complex of the Schiff base ligand (E)-1-((2-(dimethylamino)ethylimino)methyl)naphthalene-2-ol have been used. The cobalt complex (1) has been tested as an electrocatalyst for the reduction of protons in non-aqueous solvent using trifluoro acetic acid (TFA) as a substrate. Complex 1 catalyses the acid reduction at a relatively high potential (−0.7 V) with a turn over frequency of 7.05 s −1 at a 10:1 ratio of the acid to the catalyst. Production of hydrogen gas was detected by gas chromatography. The nickel complex (2) was examined for the electrocatalytic reduction of carbon dioxide. At an applied potential of −2.1 V, the main reduction product is oxalic acid. The acid produced was quantitatively determined by HPLC. The rate of oxalic acid formation is 1.3495 × 10 −7 M/min. with a kcat value of 58.03 s −1 .