Harnessing Zn-Volatility for Compositional Tuning in PtZn Nanoalloy Catalysts

TL;DR

This study demonstrates how heat treatment exploits zinc volatility to precisely tune the composition of Pt-Zn nanoalloy catalysts, enhancing their performance in propane dehydrogenation.

Contribution

It introduces a method using heat treatment and in-situ microscopy to control nanoalloy composition via zinc volatility, enabling improved catalyst design.

Findings

Zinc content decreases with heat treatment under hydrogen.

The rate of zinc loss depends on initial composition and treatment conditions.

Theoretical calculations suggest intermetallic phase stability offers compositional control.

Abstract

Bimetallic nanoalloys have gained extensive attention due to their tunable properties and wide range of catalytic applications. However, achieving good compositional control in nanoalloy catalysts remains a formidable challenge. In this work, we demonstrate that heat treatment can be used to tune the composition of Pt-Zn nanoalloy catalysts, leveraging the volatile nature of zinc to enhance their performance in propane dehydrogenation. Through identical location (scanning) transmission electron microscopy (IL-(S)TEM) using an in-situ EM gas cell, as well as other complementary techniques, we observed that the zinc content of the Pt-Zn nanoalloy particles decreased over time of the heat treatment under hydrogen. The rate of change depends on the original composition of the particles, as well as the heat treatment conditions such as temperature and flow rate. Our experimental results and theoretical calculations suggest that Zn in the intermetallic phase might be more stable, providing an opportunity for precise tuning the nanoparticle compositions. This approach presents a viable strategy for developing better Pt-Zn catalysts for propane dehydrogenation.