When constrained to ever smaller dimensions, many materials yield chemical and physical properties that are very different from their bulk analogues. Often these distinct properties are of considerable value in a wide range of technological applications. Indeed, the majority of heterogeneous catalysts that are used commercially, to refine raw fuel stocks, act as sensors, combat environmental pollution, or produce energy, rely on highly-dispersed nanoparticles (<5 nm diameter) of metals and/or metal oxides. Such nanoparticles are not passive, they adapt dynamically to their environment as they facilitate catalytic conversions. Thus the quantitative elucidation of their structure and reactive properties presents a significant challenge, requiring in situ probes that can be applied on suitable timescales. While the catalytic oxidation of CO to CO2 has been studied for almost a century, for both fundamental and applied reasons, the detailed picture of how this �simple� catalytic conversion is achieved continues to be an active area of research. This exemplifies the challenge in definitively resolving the relation between structure and function.We apply pair distribution function (PDF) methods to interrogate dilute and dynamic catalytic systems in situ, during operation. This analysis allows the structure of the nanoparticles to be probed as they are working. Insight is gained into the dynamic structure and reactivity of the catalytically active phases.

In-situ pair distribution function studies of reactivity in catalytic materials

245th National Meeting (2013)

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