“…Further developments of this type of sensor based on nonNernstian potential using noble metal-based SEs, such as Pt-SE, Mo (or Pt alloy)-SE, catalyst layer/Pt-SE, RuO 2 -SE, and Pt-SE for detection of HCs (or CO), were reported by Moseley and Tofield in 1987 [35], Vogel et al in 1993 [36], Tan et al in 1993 and [37,38], Narducci et al in 1994 [39], and Can et al in 1995 [40], respectively. Moreover, the important improvements in sensing capabilities of the mixed-potential type YSZ-based gas sensors were achieved by [41,42], Miura et al in 1995 [43] and 1996 [44][45][46][47], and Jakobs et al in 1996 [48], by replacing the noble metalbased SEs with inexpensive oxide-SEs. For example, SnO 2 , spinel-type oxides, WO 3 , and ZnO were utilized as SE materials for the mixed-potential type gas sensors to detect reducing gases [41,42], NO x [44,45], H 2 S [43,46], and H 2 [47], respectively.…”