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Light Induced Coarsening of Metal Nanoparticles

Abstract

We report a novel metal particle coarsening mechanism that is controlled by exposure of the substrate to light. Pt nanoparticles on TiO2 are observed to undergo enhanced coarsening during light illumination under conditions associated with photocatalytic water splitting. The average Pt particle size changed from 1.7 to 2.1 nm over 12 hours of photoreaction conditions whereas control experiments in the dark showed no change in Pt particle size. The coarsening is thermodynamically driven by the Gibbs-Thompson effect but is kinetically controlled by photon illumination conditions. Under illumination with photons of energy greater than the bandgap, the conductivity of the TiO2 is dramatically increased by the injection of electrons into the conduction band. This enables electron transport between particles on the substrate of differing sizes and dramatically increases the rate of Ostwald ripening. This enhanced coarsening mechanism will operate in other supported metal particle systems supported on semiconductors which harvest light via injection of electrons into the conduction band. The kinetic rate of ripening is related to the degree to which the substrate conductivity is enhance during light illumination. .

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Publication details

The article was received on 26 Nov 2018, accepted on 09 Apr 2019 and first published on 09 Apr 2019


Article type: Paper
DOI: 10.1039/C8TA11341F
Citation: J. Mater. Chem. A, 2019, Accepted Manuscript

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    Light Induced Coarsening of Metal Nanoparticles

    P. A. Crozier, Q. Liu and L. Zhang, J. Mater. Chem. A, 2019, Accepted Manuscript , DOI: 10.1039/C8TA11341F

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