Abstract
Heterogeneous catalysts drive many of the chemical transformations needed for energy security, net zero technologies, clean fuels, fertilizers and emission control. However, catalyst performance is often governed by short-lived active states that are difficult to observe under realistic reaction conditions. In this talk, I will show how steady-state, operando and time-resolved X-ray spectroscopy can be used as non-invasive diagnostics to measure these active states directly and connect them with catalytic function.
Using selected case studies, I will discuss how X-ray absorption spectroscopy and resonant inelastic X-ray scattering reveal surface hydrogen species in reverse water-gas shift reactions, nitrogen vacancies in low-temperature ammonia synthesis, carrier dynamics at Au/TiO2 Schottky interfaces, Cu redox kinetics in ammonia slip catalysis, and Pt electronic dynamics in fuel-cell catalysts. These examples demonstrate a common principle: by measuring the electronic and structural state of a working catalyst across relevant timescales, we can identify rate-determining steps, quantify reactive intermediates, and use this knowledge to design improved catalytic systems. The talk will highlight how modern X-ray methods are moving from characterisation tools towards engineering diagnostics for catalyst discovery and optimisation.