“…Most dopants studied are cations of d (Y [8], Zr [9][10][11][12][13], Hf [11], Nb [14], Mn [15], Ru [16], Zn [17], etc) and f (La [8,9,18,19], Pr [8,18,19], Nd [19,20], Sm [8,18], Gd [21], Tb [18], etc) elements, and the most promising doped-ceria active phases seem to be those with Pr, Zr or La as main dopant.…”