Guest Seminar - Catalysis enabled by operando spectroscopy: from fundamental understanding to innovative materials

Heterogeneous catalysis is of prominent importance for modern society. For example, the Fe catalysed NH3 synthesis process provides nitrogen fertilizers that lead to food production for at least half of the world’s population. It is even more important in the circular economy, providing process solutions for future energy conversion, fuel production, and waste recycling. Yet the understanding of reaction mechanisms is still limited due to the complexity of surface catalytic systems and the lack of characterization methods to directly observe surface process under working conditions.

In this talk, I will introduce new experimental designs to utilize synchrotron X-rays and X-ray free electron laser based operando spectroscopy to identify active centres and rate determine steps, which leads to the development and synthesis of novel materials that have significantly improved catalytic performance. I will present three novel operando methods:

1. Rate determination in half-reactions with quick time-resolved X-ray spectroscopy for identification of rate determining step in redox catalysis.
2. Measuring dynamics of elementary electron transfer from support to metal active site at fs to ps time scale, help to shoot the molecular movie of a single catalytic process.
3. Experimental validation of the d-band theory and direct measurement of bond energy via X-ray elastic scattering techniques.

With these first-time observations, we have been able to develop new catalysts with 5-100 times better performances than those in existing reports for emission control, H2 production, and fuel cell applications. Our new operando X-ray methods have been used beyond catalysis to energy storage and conversion systems. Such innovation has great potential in wide engineering applications.