# FeCl3-Intercalated Carbon Nanotube Film for Long-Term Infrared Camouflage in Harsh Environments

## TL;DR

A new carbon nanotube film with FeCl3 intercalation improves infrared camouflage performance and durability in harsh conditions.

## Contribution

A FeCl3-intercalated carbon nanotube film is introduced for enhanced and durable infrared camouflage.

## Key findings

- FeCl3 intercalation significantly improves infrared camouflage performance with temperature variations of up to −144 °C.
- The film maintains performance after exposure to heat, insolation, and rain.
- Intercalation reduces infrared absorptivity from 72% to 30% at 15 μm due to charge transfer and Fermi energy shift.

## Abstract

Infrared camouflage, realized by engineering temperature and spectral emission characteristics, is crucial in various scientific and engineering fields. Yet, a significant challenge lies in fabricating advanced functional materials that can durably maintain infrared camouflage performance under harsh operational conditions. Herein, we report a FeCl3-intercalated carbon nanotube (CNT) film fabricated via a vapor intercalation strategy, with FeCl3 molecules inserted into the interlayer spacing of the CNT. Compared with pristine CNT, the FeCl3-intercalated CNT composite demonstrates significantly enhanced infrared camouflage capabilities, exhibiting apparent temperature variations of +16.7 °C, −6.6 °C, and −144 °C relative to the CNT film, under low (−4 °C), body (34.3 °C), and high (300 °C) temperature backgrounds, respectively. Moreover, extensive durability tests involving heat, insolation, and rain have confirmed the unaltered infrared camouflage performance of the FeCl3-CNT film. The performance enhancement is attributed to the suppressed infrared absorptivity across the 2.5–15.2 μm wavelength range, with a pronounced reduction from 72% to 30% at 15 μm, driven by intercalation-induced charge transfer and the consequent Fermi energy (EF) shift. This work presents a promising approach for designing advanced functional materials to achieve long-term infrared camouflage in complex environments.