Degradation kinetics of organic-inorganic hybrid materials from micro-Raman spectroscopy and density-functional theory

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Ye, T., Sun, Y. -Y., Kocherga, M., & Nesmelov, A. (2023). Degradation kinetics of organic-inorganic hybrid materials from micro-Raman spectroscopy and density-functional theory. Small. https://doi.org/doi:10.1002/smll.202302935
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Graduate, Organic–inorganic hybrid materials often face a stability challenge. β-ZnTe(en)0.5, which uniquely has over 15-year real-time degradation data, is taken as a prototype structure to demonstrate an accelerated thermal aging method for assessing the intrinsic and ambient-condition long-term stability of hybrid materials. Micro-Raman spectroscopy is used to investigate the thermal degradation of β-ZnTe(en)0.5 in a protected condition and in air by monitoring the temperature dependences of the intrinsic and degradation-product Raman modes. First, to understand the intrinsic degradation mechanism, the transition state of the degradation is identified, then using a density functional theory, the intrinsic energy barrier between the transition state and ground state is calculated to be 1.70 eV, in excellent agreement with the measured thermal degradation barrier of 1.62 eV in N2 environment. Second, for the ambient-condition degradation, a reduced thermal activation barrier of 0.92 eV is obtained due to oxidation, corresponding to a projected ambient half-life of 40 years at room temperature, in general agreement with the experimental observation of no apparent degradation over 15 years. Furthermore, the study reveals a mechanism, conformation distortion enhanced stability, which plays a pivotal role in forming the high kinetic barrier, contributing greatly to the impressive long-term stability of β-ZnTe(en)0.5.

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Title

Degradation kinetics of organic-inorganic hybrid materials from micro-Raman spectroscopy and density-functional theory

Author(s)

Ye, Tang
Sun, Yi-Yang
Kocherga, Margaret
Nesmelov, Andrei

UNC Charlotte Affiliate Type

Graduate

Extent

1 online resource

Date Created

2023

Genre

articles

Resource Type

text

Abstract

Organic–inorganic hybrid materials often face a stability challenge. β-ZnTe(en)0.5, which uniquely has over 15-year real-time degradation data, is taken as a prototype structure to demonstrate an accelerated thermal aging method for assessing the intrinsic and ambient-condition long-term stability of hybrid materials. Micro-Raman spectroscopy is used to investigate the thermal degradation of β-ZnTe(en)0.5 in a protected condition and in air by monitoring the temperature dependences of the intrinsic and degradation-product Raman modes. First, to understand the intrinsic degradation mechanism, the transition state of the degradation is identified, then using a density functional theory, the intrinsic energy barrier between the transition state and ground state is calculated to be 1.70 eV, in excellent agreement with the measured thermal degradation barrier of 1.62 eV in N2 environment. Second, for the ambient-condition degradation, a reduced thermal activation barrier of 0.92 eV is obtained due to oxidation, corresponding to a projected ambient half-life of 40 years at room temperature, in general agreement with the experimental observation of no apparent degradation over 15 years. Furthermore, the study reveals a mechanism, conformation distortion enhanced stability, which plays a pivotal role in forming the high kinetic barrier, contributing greatly to the impressive long-term stability of β-ZnTe(en)0.5.

Subjects--Topics

Materials
Engineering design

Is Part Of

Small

Language

English

Published Version (Please cite this version)

doi:10.1002/smll.202302935

Publisher's Version

https://doi.org/10.1002/smll.202302935

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