The incorporation of grain boundaries when designing catalytic materials provides a readily accessible means of increasing surface defects. These defect sites contain high-energy atoms that are undercoordinated leading to an overall increase in the catalytic activity of metal nanoparticles. Herein we define a method that intentionally increases the number of grain boundaries at the surface of well-defined, symmetric palladium nanoparticles. Careful manipulation of the competitive interactions between chloride ions and bromide ions at the surface of palladium nanoparticles encourages outward growth of fin-like structures at the twin boundaries extending the surface of these strained sites while concurrently inducing uniform corrugation at the particle surface significantly increasing the number of undercoordinated atoms. The observed corrugation can be attributed to surface passivation by bromide ions and etching by chloride ions in the presence of dilute concentrations of surfactant molecules. The aforementioned twinned defects and emergence of grain boundaries result from slow reaction kinetics and selective surface passivation respectively. Notably, competitive surface interactions leading to controlled deposition and etching events as well as kinetic control of internal defect structure are applicable to other metal systems providing a potential avenue for the enhancement of diverse catalytically significant metals through increased density of surface defects.

Coupling competitive surface interactions: A synthetic route to enhanced grain boundaries at the exterior of multiply twinned palladium nanoparticles

255th National Meeting (2018)

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