Tunable optical activities in chiral transition metal oxide nanoparticles

Shuyu Xiao; Jiechun Liang; Junzi Li; Jiaji Cheng; Xi Zhu; Tingchao He

doi:10.1039/d2nr02555h

Tunable optical activities in chiral transition metal oxide nanoparticles

Nanoscale. 2022 Oct 27;14(41):15414-15421. doi: 10.1039/d2nr02555h.

Authors

Shuyu Xiao¹, Jiechun Liang², Junzi Li¹, Jiaji Cheng³, Xi Zhu², Tingchao He¹

Affiliations

¹ Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China. tche@szu.edu.cn.
² School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Shenzhen 518172, China. zhuxi@cuhk.edu.cn.
³ Country Key Laboratory of Green Preparation and Application for Functional Materials, Ministry of Education, School of Materials Science and Engineering, Hubei University, Wuhan 430062, China. jiajicheng@hubu.edu.cn.

PMID: 36218542
DOI: 10.1039/d2nr02555h

Abstract

Chiral transition metal oxides (TMOs) are widely used in various optoelectronic devices. However, the currently poor understanding of how the optical activities of TMOs can be regulated considerably hinders their applications. We have synthesized a series of chiral TMO nanoparticles (NPs), i.e., MoO_x (x = 2, 2.4 and 2.5) and Co₃O₄. Compared with TMO NPs with L-/D-cysteine molecules as the capping ligand, L-/D-histidine-capped TMO NPs possess larger anisotropic factors (g_abs), which are as high as ∼0.01 and ∼0.02 for L-/D-histidine-capped MoO_2.5 and Co₃O₄ NPs, respectively. A nondegenerate coupled oscillator (NDCO) theoretical calculation confirms that L-/D-histidine molecules can generate a smaller electric dipole moment and thus induce higher optical activity than L-/D-cysteine molecules. Impressively, the chiral NPs exhibit broadband second harmonic generation. This work indicates that chiral TMO NPs have potential for application in nonlinear optical devices.