Covalent Functionalization of Nickel Phosphide Nanocrystals with Aryl-Diazonium Salts

Ian Murphy, Peter Rice, Madison Monahan, Leo Zasada, Elisa Miller, Simone Raugei, Brandi Cossairt

Research output: Contribution to journalArticlepeer-review

9 Scopus Citations

Abstract

Covalent functionalization of Ni2P nanocrystals was demonstrated using aryl-diazonium salts. Spontaneous adsorption of aryl functional groups was observed, with surface coverages ranging from 20 to 96% depending on the native reactivity of the salt as determined by the aryl substitution pattern. Increased coverage was possible for low reactivity species using a sacrificial reductant. Functionalization was confirmed using thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The structure and energetics of this nanocrystal electrocatalyst system, as a function of ligand coverage, were explored with density functional theory calculations. The Hammett parameter of the surface functional group was found to linearly correlate with the change in Ni and P core-electron binding energies and the nanocrystal's experimentally and computationally determined work function. The electrocatalytic activity and stability of the functionalized nanocrystals for hydrogen evolution were also improved when compared to the unfunctionalized material, but a simple trend based on electrostatics was not evident. Density functional theory was used to understand this discrepancy, revealing that H adsorption energies on the covalently functionalized Ni2P also do not follow the electrostatic trend and are predictive descriptors of the experimental results.
Original languageAmerican English
Pages (from-to)9652-9665
Number of pages14
JournalChemistry of Materials
Volume33
Issue number24
DOIs
StatePublished - 2021

NREL Publication Number

  • NREL/JA-5900-80558

Keywords

  • electrocatalysts
  • nanocrystals
  • solar-photochemistry

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