(35g) Carbon Supported Ag Nanoparticles with Different Particle Size As Cathode Catalysts for Anion Exchange Membrane Fuel Cell

Two kinds of solution phase-based synthetic routes were successfully developed to prepare non-precious silver catalyst: An aqueous phase method with NaBH₄ as reducing agent, and an organic nanocapsule method with LiBEt₃H as reducing agent. XRD and TEM characterizations showed as-synthesized Ag nanoparticles (NP) based on two synthetic methods had different particle sizes (nanocapsule: 4.2-5.4 nm, aqueous phase: 13-15 nm) and both of them were well dispersed on the Vulcan XC-72 carbon black support.

The effect of Ag particle size on oxygen reduction reaction at the cathode was investigated in anion exchange membrane direct glycerol fuel cells (AEMDGFC). At the anode, high purity glycerol (99.8%) or crude glycerol (88 wt%, directly obtained from soybean biodiesel production) was used as fuel, and a commercial Pt/C served as anode catalyst. At the cathode, oxygen was used as fuel, and the self-prepared Ag/C cathode catalyst worked as cathode catalyst. A commercial Ag nanoparticle with a size 25-30 nm was also used as a control sample. Experiment results showed that higher peak power density of AEMDGFC was achieved by using smaller size Ag-NP catalyst: nanocapsule Ag-NP > aqueous phase Ag-NP > commercial Ag-NP. With the nanocapsule Ag-NP as cathode catalyst, the peak power density and open circuit voltage of AEMDGFC at 80^oC is 50 mW cm^-2, 0.70 V, and 40 mW cm^-2, 0.65 V with crude glycerol and crude glycerol, respectively. The AEMDGFC performance can be further improved by optimizing the electrode structures and test conditions, and detailed results will be presented.