CO2 reduction catalysts

Ru(bpy)2(CO)2]. The former is reduced to provide HC02 (Scheme 127). Product-selective electroreduction of CO2 to either CO or formate in an MeCN-Bu4NPF6-(Pt) system has been shown to occur using precursor complexes such as [Ru(trpy)(dppe)Cl]+ or [cis-Rh(bpy)2(TFMS)2] (trpy = 2,2 2"-tripyridine TFMS = trifluoromethane-sulfonyl anion) [338]. The Ru(II) complex is found to be a good CO2 reduction catalyst at a potential of —1.4 V (SCE) and the electrolysis results in the exclusive formation of CO (Scheme 128a). In contrast, the electroreduction of CO2... 

Tetraheterodecalin podands, their linkers, and resulting macrocycles A hoard of constitutionally and stereochemically dynamic systems 13IJC45. Thermodynamics and kinetics of CO2, CO, and H binding to the metal centre of CO2 reduction catalysts, in particular, cobalt and nickel complexes of 1,4,8,11-tetraazacyclotetradecane (cyclam) and its derivatives 12CSR2036. 

Smieja JM, Sampson MD, Grice KA, Benson EE, Froehlich JD, Kubiak CP (2013) Manganese as a substitute for rhenium in CO2 reduction catalysts the importance of acids. Inorg Chem 52(5) 2484-2491. doi 10.1021/ic302391u... 

Anfuso CL, Snoeberger RC, Ricks AM, Liu W, Xiao D et al (2011) Covalent attachment of a rhenium bipyridyl CO2 reduction catalyst to rutile Ti02. J Am Chem Soc 133 6922-6925... 

Dang T, Ramsaran R, Roy S, Froehlich J, Wang J, Kubiac CP (2011) Design of a high-throughput 25-well parallel electrolyzer for the accelerated discovery of CO2 reduction catalysts via a combinatorial approach. Electroanalysis 23 2335-2342... 

The synthesis of catalytic photocathodes for H2 evolution provides evidence that deliberate surface modification can significantly improve the overall efficiency. However, the synthesis of rugged, very active catalytic surfaces remains a challenge. The results so far establish that it is possible, by rational means, to synthesize a desired photosensitive interface and to prove the gross structure. Continued improvements in photoelectrochemical H2 evolution efficiently can be expected, while new surface catalysts are needed for N2 and CO2 reduction processes. 

Catalytic converters are basically smog control devices on newer automobiles. Catalytic converters have an oxidation catalyst that oxidizes CO and hydrocarbons to CO2 and H2O. It may also have a reduction catalyst that reduces NO to N2. The catalysts involved with these processes are generally platinum or palladium metal operating at relatively high temperature. 

In contrast, the activity of supported rhodium catalysts is determined principally by the concentration of accessible surface Rh atoms, which catalyze methane decomposition, followed by CO2 reduction (186). As a result, the support plays a minimal role in the rhodium-containing catalysts. 

Because the potential of the one-electron reduction of CO2 is — 1.9V (vs. NHE), neither the MLCT excited state nor the OER species of rhenium complexes can reduce CO2 with a single electron through outer-sphere electron transfer. As shown in Eq. (19), however, the potential for obtaining CO by two-electron reduction of CO2 shifts positively to —0.53 V (vs. NHE these potentials of CO2 reduction are close to the values in CH3CN vs. SCE (80)). Such two-electron reduction of CO2 has been reported to proceed efficiently using rhenium(I) complexes as electrochemical catalyst (Eqs. 20-22) (79,85). 

The electrocatalytic behavior of cathodes appears to play a crucial role in the reduction of carbon dioxide. To find more efficient catalysts, detailed mechanistic studies of CO2 reduction are needed. Further studies could also concentrate on the investigation of different electrolytes as well as different catalysts delivering products of choice, such as alcohols. 

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