Porous carbon (PC) materials have unique structures and excellent physicochemical properties, which offer significant advantages in the field of electromagnetic wave (EMW) absorption materials. However, how to utilize available raw materials and practical preparation techniques is a major challenge for PC microwave absorption materials to achieve engineering applications. In this study, inexpensive coal tar pitch (CTP) was used as a carbon source to prepare PC microwave absorbers. Firstly, hyper-crosslinked polymers (HCPs) were prepared by selectively crosslinking the aromatic components in CTP via Friedel-Crafts reaction using chloroalkanes as crosslinking agents. Further, PC materials with uniform structure were also prepared by simple high-temperature carbonization. The effects of cross-linker type (CH₂Cl₂, CHCl₃ and CCl₄) and carbonization temperature (600, 700, and 800 °C) on the microstructure, crystallization, dielectric and microwave absorption properties of PC materials were systematically studied. After modulation and optimization, all CTP-based PCs have uniform pore structure with a maximum specific surface area of 533.93 m²/g. The PC with CHCl₃ as cross-linking agent carbonized at 700 °C showed the exceptional microwave absorption performance, with the minimum refection loss (RL_min) of −43.08 dB and the maximum effective absorption bandwidth (EAB_max) of 5.44 GHz. Meanwhile, the RL_min of CCl₄-PC-800 also achieved −47.28 dB. This work has developed a simple and low-cost method for preparing PC microwave absorption materials, which has the potential to enable the mass production and engineering application of PCs, as well as facilitating processing technology innovation and high value-added utilization of CTP.

Graphitic carbon nitride (g-C₃N₄) nanosheets have attracted widespread interest in the construction of advanced separation membranes. However, dense stacking and a single functionality have limited the membrane development. Here, an advanced two-/three-dimensional (2D/3D) g-C₃N₄/TiO₂@MnO₂ membrane is constructed by intercalating 3D TiO₂@MnO₂ nanostructures into g-C₃N₄ nanosheets. The 3D flower-like nanostructures broaden the transport channels of the composite membrane. The membrane can effectively separate five oil-in-water (O/W) emulsions, with a maximum flux of 3265.67 ± 15.01 L·m⁻²·h⁻¹·bar⁻¹ and a maximum efficiency of 99.69% ± 0.45% for toluene-in-water emulsion (T/W). Meanwhile, the TiO₂@MnO₂ acts as an excellent electron acceptor and provides positive spatial separation of electrons–holes (e⁻–h⁺). The formation of 2D/3D heterojunctions allows the material with wider light absorption and smaller bandgap (2.10 eV). These photoelectric properties give the membrane good degradation of three different pollutants, with about 100% degradation for methylene blue (MB) and malachite green (MG). The photocatalytic antibacterial efficiency of the membrane is also about 100%. After cyclic experiment, the membrane maintains its original separation and photocatalytic capabilities. The remarkable multifunctional and self-cleaning properties of the g-C₃N₄ based membrane represent its potential value for complex wastewater treatment.