Glancing angle deposited Ni nanopillars coated with conformal, thin layers of Pt by a novel electrodeposition: Application to the oxygen reduction reaction

Highlights: • Uniform deposition of Pt under a novel rotating disc condition on GLAD (glancing angle deposited) Ni with use of the counter electrode as Pt source. • Strong attachment of the deposited Pt without using binder agents. • Superior activity of Ni_GLAD{Pt}/GC to {Pt}/GC towards oxygen reduction in base. • Significant durability of Ni_GLAD{Pt}/GC in long term oxygen reduction. - Abstract: Glancing Angle Deposition (GLAD) was used to prepare 500 nm long Ni nanopillars directly on glassy carbon disc electrodes (Ni_GLAD/GC). Ni_GLAD{Pt}/GC core-layer nanopillars were prepared by depositing Pt on the Ni_GLAD substrate via a novel rotating disc electrode galvanostatic deposition, where a stationary blackened Pt counter electrode served as the Pt source. Scanning electron microscopy, cyclic voltammetry, and inductively-coupled mass spectrometry were employed to characterize the deposits. Results indicated that the Pt was deposited in a conformal manner on the Ni_GLAD giving a loading of 11.6 μg. The Ni_GLAD{Pt}/GC electrode was ca. three fold more active than a {Pt}/GC (made with the same deposition in the absence of Ni) towards the oxygen reduction reaction (ORR) in 1.0 M KOH. As well, long term potentiostatic ORR studies showed the Ni_GLAD{Pt}/GC deposit was more durable than the {Pt}/GC, with the former completely retaining its initial performance after 5000 s polarization at 0.85 V vs. RHE, while {Pt}/GC lost 38% of its activity. Subsequent control experiments in the absence of O₂ showed that such decay was not due to loss of Pt over the prolonged ORR