The homogeneous electrochemical reduction of CO2 by the molecular catalyst [Ni(cyclam)]2+ was studied by electrochemistry and infrared spectroelectrochemistry. The electrochemical kinetics were probed by varying CO2 and proton concentrations. CO2 reduction intermediates are observed in infrared spectra obtained from spectroelectrochemical experiments. The major species observed are [Ni(cyclam)(CO)]+ and CO2 adducts of [Ni(cyclam)]+. The rate limiting step during electrocatalysis is determined to be catalyst deactivation by the CO produced from CO2 reduction. Another macrocyclic complex, [Ni(TMC)]+ (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), is deployed as a CO scavenger in order to inhibit the deactivation of [Ni(cyclam)]+ by CO. Addition of the CO scavenger is shown to dramatically increase the catalytic current for CO2 reduction. Evidence for the [Ni(TMC)]+ acting as a CO scavenger includes the observation of [Ni(TMC)(CO)]+ by IR. Recent studies of the productive scavenging of CO by uptake in tandem catalytic reactions will be reviewed. By adjustment of pH [Ni(cyclam)]2+ can catalytically cogenerate synthesis gas (CO + H2). Electrochemically produced synthesis gas was used to catalytically hydroformylate styrene in a single reactor without poisoning of [Ni(cyclam)]2+.

Homogeneous reduction of CO2 by [Ni(cyclam)]+, poisoning by CO, detoxification by CO sponge, and useful conversion of CO by tandem catalysis

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.