Accelerated Carrier Kinetics in Hollow Cubic Mott–Schottky CoFe@carbon Composites for High-Efficiency Broadband Electromagnetic Wave Absorption

The ever-growing electromagnetic pollution from modern technology calls for high-performance wave-absorbing materials that master the delicate balance between impedance matching and attenuation capability—a balance missed by conventional heterojunctions due to their sluggish carrier kinetics and performance trade-offs. Herein, we propose a multi-scale design strategy integrating Mott–Schottky heterojunctions within a hollow cubic CoFe@carbon architecture. Work function disparity between Co_0.7Fe_0.3 and carbon drives the formation of a built-in electric field, accelerating charge relaxation and enabling significant spatial charge migration. The directional movement of these charges under high-frequency electromagnetic fields effectively attenuates incident energy—critical for broadening the absorption bandwidth—while the hollow cubic morphology optimally tunes the impedance matching, essential for achieving a wide effective absorption band. This synergy between interfacial electric fields and structural features successfully breaks the conventional attenuation-matching compromise. Consequently, the optimized material achieves a remarkable ultra-wide EAB of 7.76 GHz at 2.5 mm and RL_min of −43.22 dB. Theoretical calculations confirm that the remarkable electromagnetic wave absorption performance originates from a synergistic effect, revealing the critical roles of enhanced interface polarization driven by the Mott–Schottky effect, well-optimized conductive networks, and excellent impedance matching endowed by the unique hollow cubic structure. This strategy offers profound insights into addressing the fundamental limitations of traditional absorbers and paves a promising way for developing next-generation high-performance EM functional materials.