Atomic layer deposited tantalum oxide to anchor Pt/C for a highly stable catalyst in PEMFCs

Abstract

Tantalum oxide (TaO_x) nanoparticles (NPs) are deposited on a commercial Pt/C catalyst by an area-selective atomic layer deposition (ALD) approach to enhance the stability of the catalyst in proton exchange membrane fuel cells (PEMFCs). Due to the application of a blocking agent for protecting the Pt surface, TaO_x particles are selectively nucleated and grown around Pt NPs. The TaO_x loading on the Pt/C surface could be controlled precisely by varying the number of ALD cycles. When deposited on the Pt/C surface with 35 ALD cycles, the TaO_x-anchored Pt NPs formed an excellent triple-junction structure of TaO_x–Pt–carbon. The electrochemical durability tests indicated that the TaO_x-anchored Pt/C catalyst showed comparable catalytic activity and superior long-term stability to Pt/C. Moreover, the long-term stability test in membrane electrode assembly (MEA) indicated a very low power density loss (12%) after a 120 h accelerated durability test. The significantly enhanced catalyst stability during PEMFCs operation is due to the anchoring effect of TaO_xvia strong metal oxide–support interactions. This strategy shows great potential for developing highly stable catalysts for PEMFCs.