21Electroreduction of Carbon Dioxide
1.3.2 Choice of Cathode Materials with Favourable
ElectrocatalyticProperties
The identity of the cathode materials is essential for the outcome of CO
2
elec-
troreduction. While an earlier electrode classication was based on whether
the cathode metal belonged to the sp- or the d-metal group [50], Hori con-
sidered that the performance of various metals is loosely related to the peri-
odic table. For aqueous electrolytes, Hori [82,83] suggested regrouping the
electrode metals into two categories: (1) CO formation metals (Cu, Au, Ag,
Zn, Pd, Ga, Ni and Pt) and (2) metals that yield formate (Hg, Pb, Zn, In, Sn,
Cd and Tl). As discussed in the previous section, copper represents a very
special electrode ma