Engineering nitrogen doping of silicon oxycarbide structures through tailored dendritic molecular architectures

Abstract

Polymer-derived ceramics, such as silicon oxycarbide (SiOC) materials, offer broad tunability through precursor chemistry, enabling the development of multifunctional materials. Controlling nitrogen incorporation into SiOC systems remains a key challenge to tailor their structure and properties. Here, we show that the design of dendritic molecules with triazine and amine functionalities, allows effective nitrogen doping of SiOC materials. Polymerization with allyl-hydrido polycarbosilane at controlled temperatures, followed by pyrolysis from 700 to 900 °C, leads to the integration of nitrogen both into the free-carbon phase as pyridinic-N, graphitic-N, and pyrrolic-N species, and into the glassy network through Si–N bonds. Materials polymerized at 50 °C exhibit enhanced nitrogen retention in the form of graphitic-N and greater cross-linking. This work demonstrates a molecular-level strategy to control nitrogen doping in SiOC ceramics, paving the way for the design of functional materials for advanced applications such as catalysis, energy storage, and sensing, which will be tested in future works.