Hierarchically Porous Ceramic and Metal‐Ceramic Hybrid Materials Structured by Vat Photopolymerization‐Induced Phase Separation

Abstract

Additive manufacturing techniques such as vat photopolymerization have laid the foundation for impressive advances in the 3D structuring of ceramic materials. However, simultaneous structuring of these complex-shaped ceramic objects on the sub-µm scale, an essential feature for a wide range of applications in separation, energy conversion and storage, adsorption or sensing, has remained a tremendous challenge. This study demonstrates how complex-shaped polymer-derived SiOC ceramics exhibiting hierarchical porosity ranging from the sub-µm- to the millimeter-range can be generated by combining vat photopolymerization with photopolymerization-induced phase separation using preceramic polymer-based phase-separating resins. In addition to allowing single-step, multi-level structural control, this new processing concept allows for the chemical modification of the 3D-printable, phase-separating preceramic polymer resins using organometallic compounds, including the possibility to generate functional metal nanoparticles in situ during the polymer-to-ceramic conversion. In this manner, a chemical toolbox is provided, facilitating the introduction of Ni, Co, Mo, or La into the hierarchically structured SiOC matrix. The versatile applicability of this new materials design approach is demonstrated by employing complex-shaped, hierarchically porous monoliths containing in situ generated Ni nanoparticles as heterogeneous catalysts for CO2 methanation, with a profound increase in catalyst performance attained by oxidative post-treatment of the metal-ceramic hybrid material.