Hydrothermal Synthesis to Water-stable Luminescent Carbon Dots from Acerola Fruit for Photoluminescent Composites Preparation and its Application as Sensors

Joston Carvalho,Fernando Júnior Quites,Jéferson Aparecido Moreto,Liélia Rodrigues Santos,Renato Garcia Freitas,José Carlos Germino,Ailton José Terezo

doi:10.1590/1980-5373-mr-2018-0920

Abstract

Carbon dots (C-dots) possess the attractive properties of high stability, low toxicity, good water solubility, simple synthetic routes as well as size and excitation-dependent photoluminescence (PL).The aim of this work was to synthesize photoluminescent C-dots by hydrothermal method using acerola fruit (Malpighiaemarginata) as a row material, since this fruit contains large number of organic molecules. Studies about the optimal synthesis conditions were performed, where these organic molecules were converted into C-dots by hydrothermal carbonization at 180 ºC for 18 h. The C-dots exhibited a green emission light at 459 nm when excited under UV-light ( λ ex= 370 nm). These nanomaterials were also successfully used to prepare C-dots/poly (vinyl alcohol) luminescent composites (C-dots/PVA). Both C-dots and C-dots/PVA composite films were investigated by using colorimetric visual sensor for Fe3+ metal ions detection. The results show that the prepared C-dots and C-dots/poly presented strong green emission light. The emission spectra of above materials were quenched in the presence of Fe3+ ions. Thus, highly specific “turn off” fluorescence sensing of Fe3+ was achieved using fluorescent C-dots. Regarding, this work describe that the polymeric films as sensors of metallic ions in aqueous solution appears as a new perspectives to design new composite materials.

Highlights

Photoluminescent carbon dots (C-dots), a relatively new member of the carbon nanomaterial family, were firstly produced during purification of single-walled carbon nanotubes by Xu et al[1] in 2004
Carbon dots (C-dots) were synthesized at different times and temperature via the hydrothermal carbonization method, using acerola fruit as carbon source . 8,10,25 In order to obtain C-dots with highest fluorescence intensity, the synthesis conditions such as the hydrothermal temperature and the reaction time were optimized and the results of optical properties are shown in Supporting Information (SI) as Figures S1, S2, S3 and S4
Based on the optical properties of C-dots obtained from acerola fruit, it can be seen that the absorption intensity continuously increased (Figure S1) with the increasing hydrothermal reaction temperature and the maximum of emission PL intensity was observed to reaction time of 18 h (Figures S1, S2 and S4)

Summary

Introduction

Photoluminescent carbon dots (C-dots), a relatively new member of the carbon nanomaterial family, were firstly produced during purification of single-walled carbon nanotubes by Xu et al[1] in 2004. C-dots.[2,4] it is still desirable to obtained luminescent C-dots by an easy and eco-friendly benign method with lowcost and readily available starting materials, such as using plant as raw materials[6,7,8,9]. In this sense, Jiang et al.[10] produced fluorescent carbon nanoparticles derived from natural materials of mango fruit, by the controlled carbonization method, for bio-imaging probes. Mehtaa et al.[13] and Sahu et al.[14] synthesized C-dots from apple and orange juices, respectively, using hydrothermal treatment for bio-imaging applications

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Conclusion