Multiple Schottky Contacts Motivated via Defects to Tune the Response Ability of Electromagnetic Waves

Abstract

Metal-organic framework (MOF) derivatives employed as novel microwave-absorbing materials (MAMs) have garnered significant attention due to their diverse in situ or ex situ coordinated components and the flexibility in nano-microstructure fabrication. A well-designed heterointerface can provide an optimal balance between impedance and high-loss capability. However, precisely tuning semiconductor-metal-carbon heterostructures remains a huge challenge. Herein, a multi-component NiS/Co₃S₄/NiCo@CNTs/NC nanohybrid with hollow structure is elaborately fabricated using a convenient solvothermal method followed by high-temperature pyrolysis, forming a unique heterostructure with multiple Schottky contacts. This nanohybrid demonstrates a remarkable reflection loss value of −75.9 dB at thickness of 2.6 mm. The transcendent microwave absorption (MA) capacity is primarily attributed to the intense polarization relaxation process and superb impedance-matching properties of the semiconductor/metal/carbon hybrid structure with Schottky barriers. In addition, the built-in electric field established at the Schottky heterointerfaces increases the electron transport capabilities. Notably, the controllable introduction of numerous defects into the carbon layer intensifies the interfacial polarization effect at the Schottky heterointerfaces of the nanohybrid. This study offers innovative insights into the mechanisms of polarization loss and the development of high-performance MAMs.