Designing a highly near infrared-reflective black nanoparticles for autonomous driving based on the refractive index and principle

Zambaga Otgonbayar; Jiwon Kim; Suk Jekal; Chan-Gyo Kim; Jungchul Noh; Won-Chun Oh; Chang-Min Yoon

doi:10.1016/j.jcis.2024.04.133

Designing a highly near infrared-reflective black nanoparticles for autonomous driving based on the refractive index and principle

J Colloid Interface Sci. 2024 Aug:667:663-678. doi: 10.1016/j.jcis.2024.04.133. Epub 2024 Apr 21.

Authors

Zambaga Otgonbayar¹, Jiwon Kim¹, Suk Jekal¹, Chan-Gyo Kim¹, Jungchul Noh², Won-Chun Oh³, Chang-Min Yoon⁴

Affiliations

¹ Department of Chemical and Biological Engineering, Hanbat National University, 125 Dongseo-daero, Yuseong-gu, Daejeon 34158, Korea.
² McKetta Department of Chemical Engineering and Texas Material Institute, The University of Texas at Austin, Austin, TX 78712, USA.
³ Department of Advanced Materials Science & Engineering, Hanseo University, 46 Hanseo 1-ro, Seosan-si, Chungnam 356-706, Korea.
⁴ Department of Chemical and Biological Engineering, Hanbat National University, 125 Dongseo-daero, Yuseong-gu, Daejeon 34158, Korea. Electronic address: cmyoon4321@hanbat.ac.kr.

PMID: 38670010
DOI: 10.1016/j.jcis.2024.04.133

Abstract

Hypothesis: The development of highly NIR reflective black single-shell hollow nanoparticles (BSS-HNPs) can overcome the Light Detection and Ranging (LiDAR) sensor limitations of dark-tone materials. The crystalline phase of TiO₂ and the refractive index can be controlled by calcination temperature. The formation of hollow structure and the refractive index is expected to simultaneously increase the light reflection and LiDAR detectability.

Experiments: The BSS-HNPs are synthesized using the sol-gel method, calcination, NaBH₄ reduction, and etching to form a hollow structure with true blackness. The computational bandgap calculation is conducted to determine the bandgap energy (E_g) of the white and black TiO₂ with different crystalline structures. The blackness of the as-synthesized materials is determined by the Commission on Illumination (CIE) L*a*b* color system.

Findings: The hydrophilic nature of BSS-HNPs enables the formulation of hydrophilic paints, allowing the mono-layer coating. With the synergistic effects of hollow structure and the refractive index, BSS-HNPs manifested superb NIR reflectance at LiDAR detection wavelengths. The high detectability, blackness, and hollow structure of BSS-HNPs can expand the variety of LiDAR-detectable dark-tone materials.

Keywords: Blackness; Crystalline phase; Hollow; LiDAR; Rutile phase.