Enhancing Infrared Emissivity of MWCNTs Composite Coatings via SiO 2 Size Regulation for Radiative Cooling of Analog Detector

ABSTRACT To address the sensitivity of analog detector (AD) dark current to temperature and the efficiency bottlenecks of conventional cooling, this work reports a high‐performance radiative cooling system utilizing multi‐walled carbon nanotubes/silicon dioxide (MWCNTs/SiO 2 ) composite nanonetworks. Through the synergistic coupling of passive radiative cooling and active thermoelectric cooling (TEC), the thermal management efficiency of the detector environment is significantly enhanced. The infrared radiation modulation mechanism was elucidated by finite‐difference time‐domain (FDTD) simulations, which indicate that SiO 2 particles with sizes around 500 nm can induce pronounced multiple Mie scattering. The experimentally fabricated coating achieves an average emissivity of 0.981 within the 7.5–12 µm band, showing excellent agreement with numerical predictions. Furthermore, a covalently bonded interface was constructed via dehydration esterification, ensuring uniform deposition onto aluminum oxide (Al 2 O 3 ) surfaces. Operational evaluations of the AD show that cooling from 30°C to 10°C suppresses the background dark noise by 92.96%. Moreover, applying the MWCNTs/SiO 2 composite coating to the heat‐sink surface reduces the thermal equilibration time of the integrated scheme by approximately 44% compared with pristine Al 2 O 3 heat sinks. This research provides a novel physical pathway for the high‐performance operation of precision optoelectronic systems in complex thermal environments.