3-D atomic Imaging of Catalyst Nanoparticles

• Applicant: Professorin Tong Li, Ph.D.
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 407513992

Fuel cells are one of the most promising energy conversion devices for delivering clean and efficient power for automotive and residential applications. Pt-based bimetallic heterogeneous catalysts have proven remarkably successful in catalysing fuel cells reactions. However, the effects of the operating environment on the surface composition, structure and stability of the noble metal catalysts are poorly understood at the atomic-scale. This knowledge will be required to produce the improved catalysts needed for future energy- and materials-efficient technologies. But identifying the chemical nature and 3D location of the individual atoms is a notorious challenge for the conventional surface technique, chemical spectroscopy and electron microscopy. Atom probe tomography (APT) provides uniquely powerful insights into the atomic-scale chemistry and structure of materials in three dimensions (3D). The applicant has previously pioneered the characterisation of core-shell nanoparticles by APT to produce atomic-scale data to better understand reaction mechanisms; the characterisation of catalyst nanoparticles by APT is still at a preliminary stage. In this project, APT in conjunction with high-resolution transmission electron microscopy (HRTEM) will be used to study Ir-core-Pt-shell nanoparticles (ammonia fuel cell catalyst), with the aim of revealing the three-dimensional surface and internal structure and chemistry of catalyst nanoparticles, with single-atom sensitivity, before and after electrochemical treatment. New approaches to improve the sample preparation will be developed to enhance the quality of the APT data obtained. The obtained atomic-scale information will be correlated to activity to explore reaction or degradation mechanisms, which will provide a rational guide to nano-engineering catalysts in order to develop cost-effective and high efficiency sustainable energy sources.

• DFG Programme: Research Grants