A new approach for high-resolution, three-dimensional elemental imaging has been demonstrated using soft X-ray ptychographic tomography. This technique leverages both optical density and phase contrast reconstructions to identify elements from a single-energy tilt series, reducing acquisition time by more than half compared to traditional multi-energy tomography. The method was validated on nickel-alumina catalyst particles, where nickel nanoparticles were distinguished from the porous alumina matrix with nanometer-scale resolution. By combining high optical density and low phase contrast signals near an absorption edge, nickel precipitates were identified robustly within the reconstructed volumes, providing critical insights into how metallic particles exsolve and redistribute under catalytic conditions.
This advance opens the door for efficient, element-specific 3D characterization of complex materials, with particular relevance for catalytic systems where nanoscale compositional changes drive performance. The approach not only streamlines experiments at synchrotron facilities, where acquisition time is highly limited, but also establishes a scalable framework for future studies involving multiple transition metals. Such capabilities are essential for unraveling the nanoscale dynamics of catalytic processes, and ultimately for guiding the design of more efficient and durable catalysts for environmentally important applications such as methane reforming.