Developing acid / base-resistant and low-price microwave-absorbing materials with lighter weight is highly desired for practical applications in extreme environments. Herein, we demonstrate the successful synthesis of the N-doped porous carbon material (NC) with hierarchical pore structure by the spray pyrolysis method. The large specific surface area (S_BET = 707.53 m²⸱g^-1) of materials enables multiple scattering of incident electromagnetic waves, and N doping greatly enhances the electrical conductivity of the material. Notably, single-atom Zn can adjust the local electronic structure of adjacent sites such as carbon and nitrogen atoms, induce the center of polarization, and thus change the dielectric and electronic properties of the host material. The porous carbon coating of single-atom Zn avoids the deterioration of electromagnetic parameters caused by the accumulation of magnetic particles under high-temperature pyrolysis. At the same time, they also can be used in various complex environments, such as acidic and basic environments. Ultimately, NC-1000, with high surface area, low density, and good chemical stability, obtained RL_min -50.5 dB and an EAB exceeding 5.1 GHz at the thickness of 1.9 mm. After soaking in the strong acid and base solution, the electromagnetic wave absorption performance of the material decreased by < 15 %. Widely available raw materials and a simple preparation scheme are expected to expedite industrial mass production for this novel type of materials.

Metal-organic frameworks (MOFs) have shown significant potential as photocatalysts. It has been widely assumed that all catalytic active sites within MOFs are functional in photocatalytic reactions but for a three-dimensional MOF, whether the internal catalytic active sites can effectively absorb light and actively contribute to photocatalytic reactions remains to be explored. In this context, we synthesized a two-dimensional nanosheet MOF (2D-MOF) and a three-dimensional bulk MOF (3D-MOF) composed of Zr₆ clusters and tetracarboxylic porphyrin (TCPP) by the approach described in the literature. Re(bpy)(CO)₃Cl (bpy = 2,2’-bipyridine), which has remarkable CO₂ photoreduction ability, was introduced to the two MOFs to create two new photocatalysts 2D-MOF-Re and 3D-MOF-Re, respectively. Photocatalytic CO₂ reduction experiments show that based on the equal number of catalytic active sites, the CO turnover number (TON) of 2D-MOF-Re reaches 27.8 in 6 h, which is 50 times that of 3D-MOF-Re. The result shows that certain catalytic active sites inside the bulk MOF are inactive due to the inability to absorb light. This study illuminates the potential of the dimensional reduction approach in the design of photocatalysts to exploit the capabilities fully.