Electrocatalysis for the Direct Alcohol Fuel Cell - Fuel Cell Catalysis: A Surface Science Approach - page 349

Figure 11.7 (a) Electric characteristics of a single 5 cm 2 DMFC recorded at 90 8C:
(1) Pt 0.8 Ru 0.2 /C anode; (2) Pt 0.7 Ru 0.26 Mo 0.04 /C anode. The catalyst loading was 2.0 mg cm 22 ;
O 2 : 3 bar, 120 mL min 21 ; MeOH 2.0 M: 2 bar, 2 mL min 21 . The membrane electrode assembly
(MEA) was prepared by hot pressing at 130 8C, 35 kg cm 22 for 3 minutes, the home-made
anode and the cathode (E-TEK, 2.0 mg cm 22 Pt loading, 40 wt% Pt on carbon) against
a Nafion 117 membrane. (b) Electric cell characteristics of a single 25 cm 2 DEFC recorded
at 80 8C: (1) Pt 0.9 Sn 0.1 /C anode; (2) Pt 0.86 Sn 0.1 Ru 0.04 /C anode (3.0 mg cm 22 Pt loading,
60 wt% catalyst on carbon). O 2 : 3 bar, 120 mL min 21 ; EtOH 2.0 M: 1 bar; 2 mL min 21 .
The MEA was prepared as in (a).
However, in the case of multimetallic catalysts, the problem of the stability of
the surface layer is crucial. Preferential dissolution of one metal is possible, leading
to a modification of the nature and therefore the properties of the electrocatalyst.
Changes in the size and crystal structure of nanoparticles are also possible, and
should be checked. All these problems of ageing are crucial for applications in
fuel cells.