SiOC-based ceramics are considered promising electromagnetic wave-absorbing materials because of their lightweight, high-temperature resistance, and heat insulation properties. Herein, SiOC@C ceramic nanospheres were prepared using a liquid-phase method combined with a polymer-derived ceramic (PDC) method, followed by heat treatment in N₂ and Ar atmospheres at different temperatures. The morphology, microstructure, phase composition, and electromagnetic wave absorption performance of the SiOC@C ceramic nanospheres were investigated in detail. The SiOC@C ceramic nanospheres obtained in the Ar atmosphere showed a minimum reflection loss (RL_min) of −67.03 dB, whereas the SiOC@C ceramic nanospheres obtained in the N₂ atmosphere exhibited an RL_min value of −63.76 dB. The outstanding electromagnetic wave absorption performance of the SiOC@C ceramic nanospheres was attributed to the synergistic effect between conductive loss, interfacial/defect polarization loss, multiple reflections, and scattering. Therefore, this research provides valuable insights into the design and fabrication of SiOC ceramic-based electromagnetic wave absorbers.

The development of low-cost, stable, and robust non-noble metal catalysts for water oxidation is a pivotal challenge for sustainable hydrogen production through electrocatalytic water splitting. Currently, such catalysts suffer from high overpotential and sluggish kinetics in oxygen evolution reactions (OERs). Herein, we report a "continuous" single-crystal honeycomb-like MXene/NiFeP_x–N-doped carbon (NC) heterostructure, in which ultrasmall NiFeP_x nanoparticles (NPs) encapsulated in the NC are tightly anchored on a layered MXene. Interestingly, this MXene/NiFeP_x–NC delivers outstanding OER catalytic performance, which stems from "continuous" single-crystal characteristics, abundant active sites derived from the ultrasmall NiFeP_x NPs, and the stable honeycomb-like heterostructure with an open structure. The experimental results are rationalized theoretically (by density functional theory (DFT) calculations), which suggests that it is the unique MXene/NiFeP_x–NC heterostructure that promotes the sluggish OER, thereby enabling superior durability and excellent activity with an ultralow overpotential of 240 mV at a current density of 10 mA·cm⁻².