Extended Thin-Film Electrocatalyst Structures via Pt Atomic Layer Deposition

Extended thin-film electrocatalyst structures based on PtNi nanowires, synthesized via spontaneous galvanic displacement, have shown great promise as efficient and durable catalysts for the oxygen reduction reaction in polymer electrolyte membrane fuel cells. In this work, atomic layer deposition (ALD) of Pt onto Ni nanowire (NiNW) substrates is demonstrated for the first time with the goal to develop a more scalable synthesis route based on vapor-phase deposition. ALD was used to deposit variable amounts of Pt onto NiNWs, producing PtNi nanowires with 3-16 wt % Pt. The Pt nanoparticle growth mechanism with increasing ALD cycles and physiochemical properties of as-received materials and ALD-modified catalysts was examined through a variety of techniques, including electron microscopy, X-ray diffraction, and rotating-disk-electrode analysis. A total of 30 cycles of Pt ALD followed by H-2 annealing was found to produce a catalyst with mass activity of over 4 times greater than the U.S. Department of Energy 2020 target, thereby demonstrating the potential of ALD as a method for producing gram-scale quantities of high performing extended surface electrocatalysts.