Enhanced interfacial polarization of defective porous carbon confined CoP nanoparticles forming Mott-Schottky heterojunction for efficient electromagnetic wave absorption

Integrating heterogeneous interface through nanostructure design and interfacial modification is essential to realize strengthened interfacial polarization relaxation in electromagnetic wave absorption. However, an in-depth comprehension of the interfacial polarization behavior at hetero-junction/interface is highly desired but remains a great challenge. Herein, a Mott-Schottky heterojunction consisting of honeycomb-like porous N-doped carbon confined CoP nanoparticles (CoP@HNC) is designed to elevate the interfacial polarization strength. Simultaneously, corresponding electron migration and redistribution between the heterointerface of defective carbon and CoP nanoparticles are revealed. The significant difference in the work function on both sides of heterogeneous interface boosts the interfacial polarization in high frequency region. Furthermore, the relevant spectroscopic characterizations demonstrate that electron spontaneously migrates from CoP to N-doped carbon at the heterointerface, thereby contributing to the accumulation of electron on defective carbon side and the distribution of hole on CoP side. Impressively, benefitting from the synergistic effects of three-dimensional porous conductive carbon skeleton, foreign N heteroatoms, special CoP nanoparticles, and the resultant CoP/N-doped carbon Mott-Schottky heterojunction, the CoP@HNC exhibits remarkable electromagnetic wave absorption performances with minimum reflection loss up to -60.8 dB and the maximum effective absorption bandwidth of 4.96 GHz, which is superior to most of recently reported transition metal phosphides microwave absorbing composites. The present work opens a new avenue for designing heterogeneous interface to realize strengthened microwave absorption capability and also reveals the in-depth influence of interface structure on electromagnetic wave absorption.