High Electrocatalytic Activity of RRSS-[NiIIHTIM](ClO4)2 and [NiIIDMC](ClO4)2 for Carbon Dioxide Reduction (HTIM = 2,3,9,10-Tetramethyl-1,4,8,11-tetraazacyclotetradecane, DMC = C-meso-5,12-Dimethyl-1,4,8,11-tetraazacyclotetradecane)

Abstract

Ni(cyclam){sup 2+} (cyclam = 1,4,8,11-tetraazacyclotetradecane) is a very effective and selective catalyst for the electrochemical reduction of CO{sub 2} to CO relative to the reduction of water to H{sub 2} in aqueous solution. However, photochemical reduction of CO{sub 2} using a photosensitizer, a sacrificial electron donor, and Ni(cyclam){sup 2+} as the catalyst has been only moderately successful. In order to understand the factors responsible for the superior electrocatalytic activity of Ni(cyclam){sup 2+} extensive studies have been carried out. While Ni(cyclam){sup +} adsorbed on the surface of a mercury electrode in an active species, other aspects of the catalytic mechanism have remained unclear. Here the authors report the catalytic activity in aqueous solution and the CO{sub 2} binding in acetonitrile of RRSS- and RSSR-NiHTIM(ClO{sub 4}){sub 2} (HTIM = 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradecane) and NiDMC(ClO{sub 4}{sub 4}){sub 2} (DMC = C-meso-5,12-dimethyl-1,4,8,11-tetraazacyclotetradecane) compared to those of Ni(cyclam){sup 2+}.