Green synthesis and multiGaussian analysis of carbon quantum dots from orange peels - optical properties, phonon interactions, and Huang-Rhys factor characterization

Q: How were carbon quantum dots synthesized from orange peels in this study?

They were synthesized using a sustainable hydrothermal method from carbonized orange peel waste.

Q: Which techniques were used to characterize the optical and structural properties?

UV-Vis spectroscopy, fluorescence spectroscopy, FT-IR spectroscopy, and TEM were used to determine optical and structural features.

Q: What does the Huang-Rhys factor indicate in the context of these CQDs?

The Huang-Rhys factor, derived from PL spectral analysis and the Stokes shift, quantifies electron-phonon coupling strength and helps interpret recombination dynamics.

Sep 30, 2026

Upload by Theodore

Carbon quantum dots synthesized from orange peels are produced via a sustainable hydrothermal route and systematically characterized to clarify optical and structural behavior. UV-Vis, fluorescence, FT-IR, and TEM reveal emission features that are resolved using multi-Gaussian fitting, separating zero-phonon line contributions from phonon sidebands linked to a ~0.21 eV carbonyl (C=O) stretching mode. Huang-Rhys factors from PL analysis and Stokes shift quantify electron-phonon coupling and electron recombination dynamics. Results show excitation-dependent tunable blue fluorescence, enhanced quantum yield versus prior orange-peel-derived CQDs, and stable radiative lifetimes, supporting bioimaging, optoelectronics, and sensing while validating fruit waste as a high-quality fluorescent nanomaterial precursor with defined vibronic signatures.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages14

Reading Time35 min

AccessFree to download

Introduction

Carbon nanomaterials and limitations

Carbon quantum dots as an alternative

Biomass and hydrothermal synthesis

Orange peel as a precursor

Methodology and characterization approach

Spectroscopic and microscopic characterization

Multi-Gaussian PL deconvolution

Huang-Rhys factor evaluation

Results and implications

Tunable blue fluorescence and quantum yield

Phonon interactions and recombination dynamics

Potential applications

[www. nature.com/scientificreports](www. nature.com/scientificreports) OPEN Green synthesis and multiGaussian analysis of carbon quantum dots from orange peels: optical properties, phonon interactions, and Huang-Rhys factor characterization ThiThao Vu1, Bao Long Hoang1, Thi Hoa Hoang1, Van Duong Pham2, The Nam Dao3, Thi Hong Thao Trinh4 & Duc Cuong Nguyen1􀀍 Carbon quantum dots (CQDs) have garnered considerable interest due to their distinctive optical properties, cost-effectiveness, and eco-friendly synthesis routes. This study investigates CQDs synthesized from orange peels through a sustainable hydrothermal method. The CQDs were characterized using UV-Vis spectroscopy, fluorescence spectroscopy, Fourier Transform Infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM) to elucidate their optical and structural properties. Multi-Gaussian fitting of the photoluminescence (PL) spectra was employed to deconvolute the emission profiles, revealing the contributions of the zero-phonon line (ZPL) and phonon sidebands, which correlate closely with the characteristic carbonyl (C=O) stretching mode at approximately 0.21 eV, as identified by FT-IR. The Huang-Rhys factor, calculated from both the PL spectral analysis and the Stokes shift, quantifies the electron-phonon coupling strength, providing insights into the recombination dynamics. The synthesized CQDs exhibited robust blue fluorescence under UV excitation, with excitation-wavelength-dependent tunable emission. Moreover, the CQDs achieved a significantly enhanced quantum yield compared with previously reported orange peel– derived counterparts, together with stable radiative lifetimes, demonstrating efficient radiative recombination. These features confirm their strong potential for bioimaging, optoelectronic, and sensing applications and reinforce the viability of fruit waste as a sustainable precursor for high-quality fluorescent nanomaterials with well-defined vibronic characteristics. Carbon is a key element in organic matter, giving carbon-based nanomaterials inherent biocompatibility, sustainability, availability, and low cost1. Advances in recent years have led to the development of diverse carbon nanomaterials such as fullerenes, carbon nanotubes (CNTs), graphene, and nanodiamonds. These materials have gained attention for their nanoscale structures and exceptional physicochemical properties, especially in microelectronics. However, their practical use is limited by challenges such as difficult synthesis (e.g., nanodiamonds), poor solubility (CNTs, graphene, fullerenes), and weak visible-light luminescence, which restricts their applications in optoelectronics and bioimaging1. Carbon quantum dots (CQDs) have emerged as a promising alternative. These zero-dimensional, fluorescent nanoparticles (typically < 10 nm) exhibit strong luminescence, water solubility, chemical stability, low toxicity, 1Faculty of Engineering Physics and Nanotechnology, VNU University of Engineering and Technology, Vietnam National University, 144 Xuan Thuy Street, Cau Giay, Hanoi 100000, Vietnam. 2Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan Street, Giang Vo, Hanoi 100000, Vietnam. 3Institute of Materials, Biology and Environment, Academy of Military Science and Technology, 17 Hoang Sam Street, Nghia Do, Hanoi 100000, Vietnam. 4National Institute of Drug Quality Control, Ministry of Health of Vietnam, 48 Hai BaTrung Street, Cua Nam, Hanoi 100000, Vietnam. 􀀍 email: [cuongnd@vnu.edu.vn](cuongnd@vnu.edu.vn) [www. nature.com/scientificreports/](www. nature.com/scientificreports/) and tunable optical properties2. Discovered in 2004 and formally synthesized in 20063,4, CQDs address many limitations of traditional carbon nanomaterials. Their abundant surface functional groups (e.g., –OH, – COOH,–NH2) and size-dependent electronic properties make them suitable for bioimaging, drug delivery, photocatalysis, energy devices, and more5–7. C

FAQs

How were carbon quantum dots synthesized from orange peels in this study?

They were synthesized using a sustainable hydrothermal method from carbonized orange peel waste.

Which techniques were used to characterize the optical and structural properties?

UV-Vis spectroscopy, fluorescence spectroscopy, FT-IR spectroscopy, and TEM were used to determine optical and structural features.

What does the Huang-Rhys factor indicate in the context of these CQDs?

The Huang-Rhys factor, derived from PL spectral analysis and the Stokes shift, quantifies electron-phonon coupling strength and helps interpret recombination dynamics.

Sep 30, 2026

Upload by Theodore