Performance of Pt-Ni Alloy Nanoparticles Supported on Carbon Nanotubes in Proton Exchange Membrane Fuel Cell

Highly porous ZIF-67 (Zeolitic imidazole framework) has a conductive crystalline metal organic framework (MOF) structure which was served as a precursor and template for the preparation of nitrogen-doped carbon nanotubes (NCNTs) electrocatalysts. As a first step, the chloroplatinic acid, a platinum (Pt) precursor was infiltrated in ZIF-67 with a precise amount to obtain 0.12 mg.cm-2 Pt loading. Later, the infiltrated structure was calcined at 700°C in Ar:H2 (90:10 vol%) gas mixture. Multi-walled nitrogen-doped carbon nanotubes were grown on the surface of ZIF-67 crystals following thermal activation at 700°C. The resulting PtCo-NCNTs electrocatalysts were deposited on Nafion-212 solid electrolyte membrane by spray technique to study the oxygen reduction reaction (ORR) in the presence of H2/O2 gases in a temperature range of 50-70°C. The present study elucidates the performance of nitrogen-doped carbon nanotubes ORR electrocatalysts derived from ZIF-67 and the effects of membrane electrode assembly (MEA) steaming on the performance of proton exchange membrane fuel cell (PEMFC) employing PtCo-NCNTs as ORR electrocatalysts. We observed that the peak power density at 70°C was 450 mW/cm2 for steamed membrane electrode assembly (MEA) compared to 392 mW/cm2 for an identical MEA without steaming.

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Intermetallic Platinum Alloy Nanoparticles and Single Atoms Hybrid Electrocatalysts for Proton Exchange Membrane Fuel Cells

10.21203/rs.3.rs-685784/v1 ◽

2021 ◽

Author(s):

Minhua Shao ◽

Fei Xiao ◽

Qi Wang ◽

Gui-Liang Xu ◽

Xueping Qin ◽

...

Keyword(s):

Fuel Cell ◽

Active Sites ◽

Proton Exchange Membrane ◽

Synergistic Effects ◽

Reduction Reaction ◽

Proton Exchange ◽

Alloy Nanoparticles ◽

Single Atoms ◽

Low Pt Loading ◽

Exchange Membrane

Abstract Proton exchange membrane fuel cell converts hydrogen and oxygen into electricity with zero emission1. The high cost and low durability of Pt-based electrocatalysts for oxygen reduction reaction hinder its wide applications2,3. The development of non-precious metal electrocatalysts also reaches the bottleneck because of the low activity and durability4,5. Here we rationally design a hybrid electrocatalyst consisting of atomically dispersed Pt and Fe single atoms and intermetallic PtFe alloy nanoparticles. The Pt mass activity of the hybrid catalyst is 3.5 times higher than that of commercial Pt/C in a fuel cell. More importantly, the fuel cell with an ultra-low Pt loading in the cathode (0.015 mgPt cm-2) shows unprecedented durability, with 93.6% activity retention after 100,000 cycles and no noticeable current drop at 0.6 V for at least 206 h. These results highlight the importance of the synergistic effects among active sites in hybrid electrocatalysts and provide an alternative way to design more active and durable low-Pt electrocatalysts for electrochemical devices.

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