A novel single-source precursor for SiC/HfC_xN_1−x-based ceramic nanocomposites was prepared by the reaction between allyl hydrido polycarbosilane and tetrakis(dimethylamido)hafnium(iv).

Since the 1960s, a new class of Si-based advanced ceramics called polymer-derived ceramics (PDCs) has been widely reported because of their unique capabilities to produce various ceramic materials (e.g., ceramic fibers, ceramic matrix composites, foams, films, and coatings) and their versatile applications. Particularly, due to their promising structural and functional properties for energy conversion and storage, the applications of PDCs in these fields have attracted much attention in recent years. This review highlights the recent progress in the PDC field with the focus on energy conversion and storage applications. Firstly, a brief introduction of the Si-based polymer-derived ceramics in terms of synthesis, processing, and microstructure characterization is provided, followed by a summary of PDCs used in energy conversion systems (mainly in gas turbine engines), including fundamentals and material issues, ceramic matrix composites, ceramic fibers, thermal and environmental barrier coatings, as well as high-temperature sensors. Subsequently, applications of PDCs in the field of energy storage are reviewed with a strong focus on anode materials for lithium and sodium ion batteries. The possible applications of the PDCs in Li-S batteries, supercapacitors, and fuel cells are discussed as well. Finally, a summary of the reported applications and perspectives for future research with PDCs are presented.

In order to enhance dielectric properties of polymer-derived SiC ceramics, a novel single-source-precursor was synthesized by the reaction of an allylhydrido polycarbosilane (AHPCS) and divinyl benzene (DVB) to form carbon-rich SiC. As expected, the free carbon contents of resultant SiC ceramics annealed at 1600 °C are significantly enhanced from 6.62 wt% to 44.67 wt%. After annealing at 900–1600 °C, the obtained carbon-rich SiC ceramics undergo phase separation from amorphous to crystalline feature where superfine SiC nanocrystals and turbostratic carbon networks are dispersed in an amorphous SiC(O) matrix. The dielectric properties and electromagnetic (EM) absorption performance of as-synthesized carbon-rich SiC ceramics are significantly improved by increasing the structural order and content of free carbon. For the 1600 °C ceramics mixed with paraffin wax, the minimum reflection coefficient (RC_min) reaches –56.8 dB at 15.2 GHz with the thickness of 1.51 mm and a relatively broad effective bandwidth (the bandwidth of RC values lower than –10 dB) of 4.43 GHz, indicating the excellent EM absorption performance. The carbon-rich SiC ceramics have to be considered as harsh environmental EM absorbers with excellent chemical stability, high temperature, and oxidation and corrosion resistance.

Self-supported Ni-doped Mo₂C nanoflowers assembled with ultrathin nanosheets on CFP as an excellent electrocatalyst for the hydrogen evolution reaction were prepared via a molten salt method.

Electromagnetic wave (EMW) absorbing materials have attracted much attention in recent years due to the dramatical increase of high-frequency electronic components and devices, which generate electromagnetic (EM) pollution and cause serious electromagnetic interference (EMI). Ceramics and associated (nano)composites are widely investigated as EMW absorbing materials because of their excellent mechanical properties, chemical/thermal stabilities, and oxidation/corrosion resistance. In addition to outstanding EMW absorbing performance, lightweight, flexibility and thermal resistance at high temperatures strongly affect their practical applications. Therefore, this review highlights the recent progress of advanced ceramic-based EMW absorbing materials by evaluating their vital EMW absorption parameters. First, the fundamentals of EMW absorption are briefly summarized, followed by the effects of phase/chemical composition, micro/nano structure, and morphology on the EMW absorbing performance and associated mechanisms. Furthermore, modern strategies for the preparation of lightweight, flexible and thermal resistant EMW absorbing materials are comprehensively reviewed. Finally, the perspectives of advanced-ceramics as EMW absorbing materials are discussed as well.