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A Water-Driven Switchable Material for Optical and Electronic Information Security: Electromagnetic Shielding and
Junjie Deng1, Jiahui Liu1, Bowen Zhang2,3
1Hubei Engineering Technology Research Center of Spectrum and Imaging Instrument, Electronic Information School, Wuhan University, Wuhan, Hubei, China.
Advanced Materials (Deerfield Beach, Fla.)
|January 9, 2026
Summary
This study presents a novel hydrogel using copper-doped carbon dots for microwave absorption and phosphorescence. This material offers advanced electromagnetic protection and optical applications.
Area of Science:
- Materials Science
- Nanotechnology
- Chemistry
Background:
- Hydrogels are versatile materials with tunable properties.
- Developing multifunctional materials for diverse applications is a key research area.
- Electromagnetic interference (EMI) shielding and optical functionalities are desirable in advanced materials.
Purpose of the Study:
- To design a multifunctional hydrogel with both wet-state microwave absorption and dry-state phosphorescence.
- To investigate the role of copper-doped carbon dots (Cu$_{x}$-CDs) in modulating hydrogel properties.
- To explore the potential applications of this stimuli-responsive material.
Main Methods:
- Incorporation of Cu$_{x}$-CDs into a polyacrylamide/carboxymethyl cellulose (PAM/CMC) hydrogel network.
- Characterization of electromagnetic absorption properties (reflection loss, absorption bandwidth).
- Density functional theory (DFT) calculations to understand electronic structure and charge transfer.
- Evaluation of phosphorescence properties upon dehydration.
Main Results:
- The optimized hydrogel achieved a minimum reflection loss of -62.67 dB and an effective absorption bandwidth of 5.94 GHz (2-18 GHz).
- Cu doping enhanced dielectric loss and absorption efficiency by regulating the hydrogen-bond network and water state.
- Dehydration induced a transition to stable blue and green room-temperature phosphorescence.
- DFT calculations confirmed Cu-N coordination's role in reducing energy gap and enhancing electronic delocalization.
Conclusions:
- A multifunctional hydrogel with synergistic wet-state microwave absorption and dry-state phosphorescence was successfully designed.
- Cu doping and hydrogen-bond engineering are key to achieving stimuli-responsive electromagnetic and optical behaviors.
- This work presents a novel strategy for multifunctional materials with potential in EMI shielding, information encryption, and anti-counterfeiting.
