Contrasting the EXAFS obtained under air and H2 environments to reveal details of the surface structure of Pt–Sn nanoparticles

DOI: 10.1039/D1CP00979F

Authors: Haoliang Huang (University of Southampton) , Abu Bakr Ahmed Amine Nassr (University of Southampton; Fraunhofer Institute for Microstructure of Materials and System) , Veronica Celorrio (Diamond Light Source) , Diego Gianolio (Diamond Light Source) , Christopher Hardacre (The University of Manchester) , Dan J. L. Brett (University College London (UCL),) , Andrea E. Russell (University of Southampton)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Chemistry Chemical Physics , VOL 30

State: Published (Approved)
Published: May 2021
Diamond Proposal Number(s): 10306 , 19850

Abstract: Understanding the surface structure of bimetallic nanoparticles is crucial for heterogeneous catalysis. Although surface contraction has been established in monometallic systems, less is known for bimetallic systems, especially of nanoparticles. In this work, the bond length contraction on the surface of bimetallic nanoparticles is revealed by XAS in H2 at room temperature on dealloyed Pt–Sn nanoparticles, where most Sn atoms were oxidized and segregated to the surface when measured in air. The average Sn–Pt bond length is found to be ∼0.09 Å shorter than observed in the bulk. To ascertain the effect of the Sn location on the decrease of the average bond length, Pt–Sn samples with lower surface-to-bulk Sn ratios than the dealloyed Pt–Sn were studied. The structural information specifically from the surface was extracted from the averaged XAS results using an improved fitting model combining the data measured in H2 and in air. Two samples prepared so as to ensure the absence of Sn in the bulk were also studied in the same fashion. The bond length of surface Sn–Pt and the corresponding coordination number obtained in this study show a nearly linear correlation, the origin of which is discussed and attributed to the poor overlap between the Sn 5p orbitals and the available orbitals of the Pt surface atoms.

Subject Areas: Chemistry, Materials


Instruments: B18-Core EXAFS

Added On: 14/05/2021 09:20

Documents:
d1cp00979f.pdf

Discipline Tags:

Surfaces Physics Physical Chemistry Catalysis Chemistry Inorganic Chemistry Nanoscience/Nanotechnology

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS)