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.
Professor Ryan Wang is Professor of Chemical Engineering at University College London. He received his BSc in Chemistry (2006) and PhD in Chemistry (2012) from Peking University, before moving to Germany for postdoctoral research at the Max-Planck-Institut für Kohlenforschung (2013-2015), supported by an Alexander von Humboldt Research Fellowship. He moved to UCL as a lecturer in 2016, and was promoted to associate professor (2021) and professor (2025). His research sits at the interface of chemical engineering, materials and chemistry, and focuses on developing and applying advanced X-ray methods to study catalysts and energy materials under real operating conditions. By revealing how active sites, electrons, and structures evolve during reaction, his work helps connect fundamental understanding to practical engineering challenges. His research has applications in green hydrogen, ammonia synthesis and utilisation, CO2 conversion, emission control, fuel cells, and cleaner chemical manufacturing. Alongside his research, he also contributes to the UK research community through national infrastructure and funding-related roles, including service on the EPSRC High-level Group of National Research Facility, Diamond Light Source and ESRF panels, as well as previous EPSRC strategic and equipment advisory activities.