Morphological Instability in Topologically Complex, Three-Dimensional Electrocatalytic Nanostructures

Abstract

Advances in electrocatalyst functionality have resulted from the evolution of complex nanostructured materials with increasing degrees of compositional and morphological complexity. Focused almost entirely on pushing the boundaries of intrinsic activity, electrocatalytic material development often overlooks stability. Operating in parallel to the typical mechanisms of electrochemical material degradation, three-dimensional nanomaterials are susceptible to an additional degradation process known as coarsening. Driven by the reduction of surface free energy, surface diffusion evolves the nanoporous morphology toward a solid spherical particle. Here, using nanoporous NiPt alloy nanoparticles (np-NiPt/C) as a representative three-dimensional electrocatalytic material, we demonstrate that coarsening is the dominant mechanism of degradation as observed during accelerated durability testing (ADT). The upper potential limit (UPL) of the ADT protocol is found to have a significant impact on coarsening, with the ra...