(51d) In Situ Catalyst Characterization Tools at NIST-Operated X-Ray Beamlines

A growing number of catalyst characterization tools have recently been established at the hard and soft X-ray beamlines NIST operates at the National Synchrotron Light Source II. Here, I will discuss several of the techniques available in the context of recent in situ studies. First, in situ X-ray absorption fine structure (XAFS) measurements of a transition metal-exchanged zeolite were collected throughout the material’s activation and use as a dehydrogenation catalyst. These measurements revealed the coordination site of the metal and tracked its electronic structure throughout the reaction. Differences between the material’s structure in its activated and spent state will be highlighted and related to its catalytic performance which was simultaneously tracked via mass spectrometry. Second, capabilities were recently extended beyond thermocatalytic studies to in situ electrocatalysis. These capabilities will be showcased in the context of their recent application to CO₂ valorization. On the soft X-ray side, complementary results were obtained by leveraging a NIST-built transition-edge sensor array to conduct partial fluorescence yield measurements of the near edge X-ray absorption fine structure (NEXAFS). Beyond presenting these capabilities, a brief overview of a recently launched project to enable in situ, time-resolved resonant inelastic X-ray scattering at the soft X-ray beamline will be discussed.