Photo-electro-chemical reduction

In particular, the photo(electro)chemical reduction of carbon dioxide is connected to one of the most important environmental problems necessitating an urgent solution, that is, the fixation of CO2 in the atmosphere. The feasibility of CO2... 

Tinnemans et al.132 have examined the photo(electro)chemical and electrochemical reduction of C02 using some tetraazamacrocyclic Co(II) and Ni(II) complexes as catalysts. CO and H2 were the products. Pearce and Pletcher133 have investigated the mechanism of the reduction of C02 in acetonitrile-water mixtures by using square planar complexes of nickel and cobalt with macrocyclic ligands in solution as catalysts. CO was the reduction product with no significant amounts of either formic or oxalic acids... 

Tinnemans, A.H.A., Koster, T.P.M., Thewissen, D.H.M.W. and Mackor A. 1984. Tetraaza-macrocyclic cobalt(II) and nickel(II) complexes as electrontransfer agents in the photo( electro )chemical and electrochemical reduction of carbon dioxide. Recl.Trav.Chim. Pavs-Bas 103. 288-295. 

A number of 14-membered tetraazamacrocyclic complexes serve as catalysts for photochemical and electrochemical CO2 reduction. [CoHMD(H20)](C104)2 (HMD = 5,7,7, 12,14,14-hexamethyl-l,4,8,1 l-tetraaza-cyclotetradeca-4,11-diene) [ 1,2] and Ni(cyclam)Cl2 (cyclam = 1,4,8,11-tetraazacyclotetradecane) [3] have been used as electrocatalysts for the reduction of CO2 in H2O or aqueous CH3CN. The ratio for CO/H2 production is 1 for [CoHMD(H20)](C104)2 and >100 for Ni(cyclam)Cl2. Metal(I) complexes, metal(III) hydride complexes, and metallocarboxylates such as [Ni (cyclam)(C02 )] are postulated as intermediates in the electro- and photo-chemical CO2 reduction [4]. 

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