Key Steps and Aspects in CO2 Reduction

The potentials of the various reactions of reduction of CO2 to other Cl molecules are shown in Table 8.1. It is quite evident that the one-electron transfer is a process that requires higher energy than the multi-electron transfers. If the reductions are considered to take place in water, then it is useful to recall the Frost diagram built by correlating the number of electrons transferred in a process and the free energy change (or electrochemical potential Table 8.1) of that process (Fig. 8.2). 

An important message from such a diagram is that any species that lies above a line joining two other different species to which it is correlated is not stable with 

Another important factor that influences the reduction process is the solvent. Table 8.3 shows the solubility of CO2 in various organic solvents [31]. It should be 

A paradox is that in a basic solutirai (pH = 10) a much greater amount of CO2 is captured in water than at pH = 7, but the available [CO2] at pH = 10 is almost equal to zero, although it is appreciable at pH = 7 (Fig. 8.6). Consequently, basic condi-ti(Mis are not suitable for studying the reactivity of CO2 itself other species such as HCOa or CO react instead. This is a key point when dealing with reactions in 

E Product of reduction of CO2 Structure of the ligand Metal centre Potential V vs. SCE Current efficiency, %tic Co-product % Solvent Process EC, PEC, PC TON (TOE) Notes Refs. 

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