Nanoscale Porosity of High Surface Area Gadolinium Oxide Nanofoam Obtained With Combustion Synthesis

Nanoscale gadolinium oxide (Gd₂O₃) is a promising nanomaterial with unique physicochemical properties that finds various applications ranging from biomedicine to catalysis. The preparation of highly porous Gd₂O₃ nanofoam greatly increases its surface area thereby boosting its potential for functional use in applications such as water purification processes and in catalytic applications. By using the combustion synthesis method, a strong exothermic redox reaction between gadolinium nitrate hexahydrate and glycine causes the formation of crystalline nanoporous Gd₂O₃. In this study, the synthesis of Gd₂O₃ nanofoam is achieved with combustion synthesis at large scale (grams). Its nanoscale porosity is investigated by nitrogen physisorption and its nanoscale 3D structure by electron tomography, and the formation process is investigated as well by means of in situ heating inside the transmission electron microscope. The bulk nanofoam product is highly crystalline and porous with a surface area of 67 m² g⁻¹ as measured by physisorption, in good agreement with the electron tomographic 3D reconstructions showing an intricate interconnected pore network with pore sizes varying from 2 to 3 nm to tens of nanometers. In situ heating experiments point to many possibilities for tuning the porosity of the Gd₂O₃ nanofoam by varying the experimental synthesis conditions.