Atomic Tuning in Electrically Conducting Bimetallic Organic Frameworks for Controllable Electromagnetic Wave Absorption

Due to the structural complexity and limited controllability of conventional microwave-absorption materials (MAMs), the precise regulation of atomically-resolved structures and properties of MAMs remains a significant challenge. The interpretation of the dielectric loss mechanism is usually conduction and polarization losses, while the absence of components-regulated template materials further hinders the disclosure of the mechanism. Herein, based on the customizable functionality of the MOF platform, a series of pristine bimetallic MOFs with precise and controllable conductivity are successfully constructed through the bimetallic alloying strategy. The controllability is attributed to the alteration of free-carrier concentration and the subtle difference of interlayer displacement or spacing, both of which originate from the atomic tuning of hetero-metal. Notably, Cu1.3Ni1.7(HITP)(2) features an ultra-high absorption strength (reflection loss, RL = -71.5 dB) and an ultra-wide maximum bandwidth (6.16 GHz) at only 15% filling, which ranked in the upper range of all reported MAMs. Due to the metal co-synergies, Cu1.3Ni1.7(HITP)(2) possesses a switchable high absorption peak in a wide range (4-18 GHz). This work opens up an avenue for tailoring the atomic tuning of new MOF-based electromagnetic wave absorbers and provides a conceptually novel platform.

Automated summary

Due to the complexity and limited control of conventional microwave-absorption materials (MAMs), the precise regulation of atomically-resolved structures and properties of MAMs remains a challenge. In this study, a series of bimetallic MOFs with precise and controllable conductivity were successfully constructed using the customizable functionality of the MOF platform. The controllability was achieved through the alteration of free-carrier concentration and subtle differences in interlayer displacement or spacing, resulting from atomic tuning. Notably, Cu1.3Ni1.7(HITP)(2) exhibited exceptional absorption strength and wide bandwidth, ranking among the highest reported MAMs.