Key physical and chemical phenomena that govern the performance of complex functional systems occur at meso and nanoscales and a crucial requisite for understanding such phenomena is exploring materials structure and composition at their natural length scales. In this respect complementary capabilities of synchrotron-based X-ray microscopes in terms of imaging, spectroscopy, spatial, depth and time resolution have opened unique opportunities to explore the properties of micro- and nano-structured objects as a function of their dimensions, morphology and operation conditions . Some recent achievements will be illustrated by selected studies addressing intrinsic heterogeneity, structural and chemical evolutions of free-standing nanostructures , multicomponent functional materials relevant to catalysis and electrode/electrolyte interfaces . The results will show how experiments combing chemical imaging with photoelectron, fluorescence or near edge absorption micro-spectroscopy at relevant length scales have led to comprehension of the system properties and the events occurring during operation conditions. Ongoing efforts for pushing the lateral resolution by implementing ptychography and development of set-ups for characterization under realistic working conditions will be outlined .
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