Energy‐dependent full‐field transmission soft X‐ray microscopy is a powerful technique that provides chemical information with spatial resolution at the nanoscale. Oxygen K‐level transitions can be optimally detected, and we used this technique to study the discharge products of lithium‐oxygen batteries, where this element undergoes a complex chemistry, involving at least three different oxidation states and formation of nanostructured deposits. We unambiguously demonstrated the presence of significant amounts of superoxide forming a composite with peroxide, and secondary products such as carbonates or hydroxide. In this chapter, we describe the technique from the fundamental to the observation of discharged electrodes to illustrate how this tool can help obtaining a more comprehensive view of the phenomena taking place in metal air batteries and any system involving nanomaterials with a complex chemistry.
In this work, we aim to evaluate the potential of hydrothermal carbonization (also known as wet pyrolysis) as a pretreatment, by evaluating the changes induced in the raw material (cellulose) under varying experimental conditions. Hydrocarbonization processes were performed under different temperature, time and biomass/water ratios following a response surface methodology. The hydrochars obtained were characterized in terms of proximate analysis, behavior towards pyrolysis and combustion, heating value and surface textural and chemical features. The presence of typical hydrocarbonization reactions (dehydration, hydrolysis, decarboxylation, decarbonylation, recondensation, etc.) was only possible if a limit temperature (200°C) was used. Under these conditions, proximate analyses changed, the surface chemistry was modified, and the formation of a second lignite-type solid fraction was observed.
Part of the book: Analytical Pyrolysis