Synergistic S/Se Co-Doping enables Exceptional microwave absorption in novel graphdiyne composite microspheres

Enhancing the conduction and polarization properties of graphdiyne (GDY), a novel carbon allotrope, is crucial for expanding its applications in microwave absorption. This work proposed dual-anion (S/Se) doping within the unique sp./sp² hybridized network of GDY to modulate the band structure and charge distribution, which enhanced the microwave absorption performance of GDY effectively. The strategy started with one-pot synthesis of the Cu₂O/GDY precursor, followed by annealing the precursor with simultaneous introduction of S and Se anions to facilitate the transformation of Cu₂O into Cu_1.8S_xSe_1-x nanoparticles embedded within the S/Se co-doped GDY network, successfully constructing Cu_1.8S_xSe_1-x/S,Se-GDY composites. Benefiting from the precisely tuned electronic properties arising from S/Se doping and the generated abundant heterogeneous interfaces, the obtained optimal composite Se-75 % exhibited a remarkably high effective absorption bandwidth (EAB) of 6.52 GHz at a thin matching thickness of 2.3 mm. Compared with pristine GDY microspheres, the EAB of the co-doped broadened by 27 %, and the minimum reflection loss (RL_min) significantly decreased from −19.67 dB to −54.56 dB. Theoretical calculations and experimental validation confirmed that an appropriate S/Se doping ratio promotes superior synergy among dipole polarization, interfacial polarization, conduction loss, and impedance matching. This work provides a novel strategy for designing and optimizing GDY-based composite microwave absorbers and offers a practical approach for tuning the microwave absorption properties of carbon-based materials.