Graphdiyne-Based Electrochemical Emissivity Modulator

Electrically controlling the emissivity provides a dynamic, precise, and low-energy-consuming solution for thermal radiation manipulation. The adjustable bandgap, abundant pores, physical stability, and electrochemical activity mean that graph-diyne (GDY) has great potential in electrically emissivity regulation. In this study, a GDY nanowall was successfully synthesized through a cross-coupling reaction with a controlled monomer concentration. Besides the morphology and micro-structure characterizations, the intrinsic integrated emissivity in the wavelength of 2-20 mu m was determined to be 0.66. Afterward, GDY composited with graphene was utilized as the electrode to fabricate an electrochemical device and emissivity modulator, with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide serving as the electrolyte. Interestingly, the GDY-based modulator demonstrated a unique capacity to modulate emissivity under a negative voltage, unlike pure graphene and other materials that can only regulate emissivity under a positive voltage. To explore the dynamic control mechanism of GDY, an in situ Raman characterization was performed, which revealed a considerable redshift and decrease in the intensity of the characteristic alkyne peaks. We proposed that the novel emissivity tuneability of GDY is caused by the cation-induced changes in the alkyne bond. Alkyne bonds transform into alkene bonds by coordinating with 1-ethyl-3-methylimidazolium cations in the presence of an electrical field, resulting in an energy level change and a change in the optical properties of GDY. These discoveries may open the way for the application of GDY in thermal radiation control and the study of molecular-scale active materials in electro-optical modulation.

Automated summary

Electrically controlling the emissivity is a low-energy-consuming solution for thermal radiation manipulation. Graph-diyne (GDY) has the potential to regulate emissivity due to its adjustable bandgap, abundant pores, physical stability, and electrochemical activity. A GDY nanowall with an intrinsic emissivity of 0.66 in the wavelength of 2-20 μm was successfully synthesized. The GDY-based emissivity modulator demonstrated a unique capacity to modulate emissivity under a negative voltage. In situ Raman characterization revealed changes in the alkyne bonds of GDY, which may explain its novel emissivity tunability.