Small-angle X-ray scattering of nanoporous materials

Small-angle X-ray Scattering (SAXS) is a non-invasive reciprocal space characterization technique that provides statistically representative microstructural information about a material. This focus article examines SAXS as a tool to probe the microstructure of nanoporous materials. We seek to educate the reader on scattering instrumentation and requisite scattering theory pertinent to nanoporous materials, and describe analytical models used to fit SAXS data, to elucidate the microstructure of these nanoporous materials including their morphological features such as the pore size distribution, pore curvature, and specific surface area. Finally, we fit and compare the aforementioned models to real scattering data of nanoporous gold synthesized in our laboratory. The models yield realistic material parameters for the nanoporous gold morphology, in agreement with electron micrograph images. In addition, we have investigated the scattering patterns and characteristic electron micrographs of nanoporous copper and nanoporous antimony also synthesized in our laboratory. The models discussed in this paper do not yield realistic material parameters for specific nanoporous copper and nanoporous antimony morphologies, however. This could be the subject of follow-up work.