(375g) Bimetallic Atomic Layer Deposition for Extended Surface Electrocatalysts

Extended surface electrocatalysts based on nanowire templates have emerged as promising candidates for advanced catalysts for the oxygen reduction reaction (ORR) in fuel cell applications. When synthesized by spontaneous galvanic displacement (SGD), these extended surface electrocatalysts have demonstrated exceptional performance (specific activity > 6000 μA/cm²) and superior durability to benchmark carbon-supported Pt catalysts. However, challenges in scale-up and reproducibility of this fabrication process have prompted an investigation into atomic layer deposition (ALD) as a facile, scalable synthesis alternative for the production of extended thin film electrocatalyst structures. The use of a bimetallic ALD process may also allow for tunable control of multiple deposited metals, as opposed to monometallic deposition with SGD. An ALD analog of the SGD synthesis process was developed by combining oxidative Pt and Ni ALD chemistries into various “supercycle” configurations and depositing these metals onto a cobalt nanowire substrate in a viscous flow reactor. In situ mass spectrometry was used to study the deposition reactions, while elemental analysis, transmission electron microscopy, elemental mapping and X-ray diffraction were used to characterize Pt growth and effects of post-treatment procedures, such as H₂ annealing.