Polymer-derived ceramics (PDCs) are a kind of advanced materials prepared by high-temperature pyrolysis of silicon-based precursors, and they exhibit a series of excellent properties, such as outstanding physical and chemical stabilities, flexible designability and easy processability. Furthermore, suitable modification of the precursors leads to multiphase ceramics known as polymer-derived ceramic nanocomposites (PDC-NCs), which in some cases exhibit enhanced properties compared to those of the original materials. Nowadays, the application of PDC-NCs is no longer limited to the high-temperature and high-strength structural materials, by doping different metals, a series of heterogeneous catalysts with unique microstructures and excellent catalytic properties can be synthesized via PDC approach. This article proposed an overview of the research progress on the preparation of PDC-NCs and their catalytic properties in the last 20 a. The main topics is related to the chemical composition design of polymeric precursors, the construction of porous structure, and the characterization of catalytic properties. Finally, the current challenges and perspectives on the field of porous PDC-NCs preparation and their application in catalysis are discussed.

The properties of PDC-NCs were directly affected by the composition and the architecture of the precursors, which provided enormous potential in tuning the microstructure and properties of the PDC-NCs via the various dopants. Metal containing PDC-NCs can be conveniently synthesized via the chemical modification of the precursors and physical blending, the obtained ceramics were endowed with different catalytic properties. In chemical modification, metal elements were linked to silicon-based precursor molecules via chemical reactions between precursors and metallic compounds. Three typical of metallic compounds have been summarized here: metal chlorides, acetylacetonate metal compounds and metal complex. Active groups like Si—H, N—H and C=C of precursors were convenience to the chemical modification. The metallic elements were homogeneously introduced into single-source precursors at the molecular level, which of great significance to prepare heterogeneous catalysts with high activity and stability. In physical blending, metallic compounds have been simply mixed with precursors through ultrasound, ball milling, or impregnation, and then PDC-NCs can be obtained via a simply pyrolysis process of these mixtures. Although there were still some drawbacks such as nonuniform element dispersion and relatively low catalytic performance, the physical blending approach is still a promising route to produce catalysts owing to the simple technologic process, cheap and wide source of raw materials, etc.

Additionally, the porous structure in heterogeneous catalysts exhibited a crucial influence on its properties, as high porosity could increase the specific surface area (SSA) of ceramics, and more catalytic active sites can be exposed, which is beneficial for improving catalytic efficiency. While appropriate pore size and porous structure are conducive to the diffusion and transport of reactants and products. Mesopores can be constructed in PDC-NCs via the introduction of hard/soft templates and even template-free method. The porous morphology and pore size can be regulated at the meso-scale by changing the templates and pyrolysis program, thereby further promoting the catalytic performance.

Many studies indicated that PDC-NCs with precise composition and structure design could be used as heterogeneous catalysts and showed excellent catalytic performance in the fields of catalytic synthesis, pollution treatment and new energy development. The polymeric precursors can be modified easily by various metallic compounds due to its superior molecular designability, after high-temperature pyrolysis, the ceramic skeleton can be applied as robust support materials to disperse and anchor active metallic nanoparticles. Moreover, the distinct characteristics such as adjustable SSA, pore volume, surface hydrophilicity or lipophilicity, as well as chemical resistance towards reaction medium, making porous PDC-NCs showed significant advantages for catalysis in harsh environments.