Heterogeneous catalysis accounts for approximately 90% of chemical production worldwide and is essential both for guiding a chemical reaction toward the desired product and for reducing the energy required for that process.
Image Credit: Thermo Fisher Scientific – Elemental Analyzers and Phase Analyzers
The active surface of the catalyst is the most important part of heterogeneous catalysis, which achieves the best efficiency. As a result, activated base materials, usually ceramics with a high surface area or carbon, are infused with metal nanoparticles, the active compound.
Measuring the size of the nanoparticles, especially after the materials have been recycled, is one method of measuring catalyst quality. X-ray diffraction (XRD) is the most widely used method to define the crystallite size of nanoparticles.
Using the Scherrer equation, the peak width of the XRD reflections is directly correlated with the size of the scattering domain. As a result, it is possible to conclude the crystallite size (CS) by determining the reflection width in the diffraction pattern.
Image Credit: Thermo Fisher Scientific – Elemental Analyzers and Phase Analyzers
The Thermo Scientific™ ARL™ EQUINOX 100 X-ray diffractometer
The Thermo Scientific™ ARL™ EQUINOX 100 X-ray diffractometer uses a custom-designed Cu microfocus tube (50 W) with mirror optics for high flux, which means no external water cooler is required.
Thanks to its unique curved position sensitive (CPS) detector, the ARL EQUINOX 100 diffractometer can offer fast data collection times that measure all diffraction peaks simultaneously. The ARL EQUINOX 100 diffractometer is therefore perfect for measuring transmission and reflection.
case study
For XRD measurements, the Pt/C powder was measured for 5 min in reflection with a zero background sample cup. MDI JADE 2010 was used to determine crystallite size using the Williamson-Hall method.
results
A Le Bail fit was used to determine the FWHM of the reflections. The Williamson-Hall method (see Figure 1) was then used to calculate the CS. Strain and instrument magnification, defined from NIST660 LaB6, was also considered. Refinements provided a CS of 2.5 nm. This result strongly aligns with the values seen in the literature.
Figure 1. Diffraction pattern of Pt/C (green: Pt; blue: C); Williamson-Hall plot of Pt/C (red area indicates 1.5 σ). Image Credit: Thermo Fisher Scientific – Elemental Analyzers and Phase Analyzers
Summary
The ARL EQUINOX 100 benchtop X-ray diffractometer proves to be a convenient solution for those wishing to quickly and easily determine the CS of Pt nanoparticles on Pt/C catalysts, especially when used in conjunction with the MDI JADE 2010 software suite .
Acknowledgments
Produced from materials originally written by Dr. Simon Welzmiller of Thermo Fisher Scientific.
This information has been obtained, reviewed and adapted from materials provided by Thermo Fisher Scientific – Elemental Analyzers and Phase Analyzers.
For more information on this source, visit Thermo Fisher Scientific – Elemental Analyzers and Phase Analyzers.