Progress in electron tomography to assess the 3D nanostructure of catalysts

The activity, selectivity and stability of solid catalysts depend critically on the details of their structure at all relevant length scales. Electron tomography (or 3D-TEM) has emerged as a powerful technique for nanostructural characterization. In this review we highlight recent advances in the field of electron tomography for the analysis of solid catalyst. Several examples demonstrate how unique quantitative information can be derived on relevant structural properties such as pore connectivity and corrugation, particle size distributions, and the 3D location of metal nanoparticles in porous oxide or carbon supports. The development of high-resolution imaging and novel reconstruction algorithms is promising to obtain atomically resolved electron tomograms of single catalyst nanoparticles. New reconstruction algorithms allow reconstruction from only a few projections, and hold potential for analyzing beam sensitive samples, as well as for time resolved electron tomography. Element specific or 'chemical' electron tomography, using electron energy-loss (EELS) or energy-dispersive X-ray spectroscopy (EDX), is an emerging tool for obtaining both chemical and structural information at nanoscale resolution. The rapid progress in electron tomography over the past few years holds great promise for detailed and quantitative insight into relevant nanostructural properties, thus allowing us to further develop our understanding of the relation between nanostructure and performance for catalysts and related materials.