Optical properties of chitosan/hydroxyl-functionalized graphene quantum dots thin film for potential optical detection of ferric (III) ion

• Published in: Optics and laser technology 2019-12, Vol.120, p.105724, Article 105724
• Main Authors: Anas, Nur Ain Asyiqin, Fen, Yap Wing, Omar, Nur Alia Sheh, Ramdzan, Nur Syahira Md, Daniyal, Wan Mohd Ebtisyam Mustaqim Mohd, Saleviter, Silvan, Zainudin, Afiq Azri
• Format: Article
• Language: English
• Subjects: Affinity; Atomic force microscopy; Carboxylic acids; Chitosan; Ferric ion; Ferric ions; Fourier transforms; Graphene; Hydroxyl groups; Morphology; Optical properties; Photoluminescence; Quantum dots; Sensing; Spectrum analysis; Spin coating; Surface chemistry; Surface plasmon resonance; Thin films
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2019.105724

•The preparation of Cs/HGQDs composite thin film has been proposed.•The Cs/HGQDs thin film was characterized using FTIR, UV–Vis, PL and AFM.•The study proved that Cs/HGQDs thin film can detect Fe3+ using SPR spectroscopy. In this research, the preparation of chitosan and hydroxyl-functionalized graphene quantum dots (HGQDs) composite has been described. The spin coating technique was used to prepare the chitosan/hydroxyl-functionalized graphene quantum dots (Cs/HGQDs) thin film. The Cs/HGQDs thin film was then characterized using the Fourier transform infrared spectroscopy which confirmed the existence of amino groups, carboxylic acid groups, carboxyl groups and hydroxyl groups in Cs/HGQDs. UV–Vis absorption spectroscopy and photoluminescence (PL) were used to study the optical properties of the thin film. The absorption of Cs/HGQDs thin film was high with optical band gap of 3.797 eV. The intensity of PL spectra of the thin film was observed around wavelength of 420 nm. The incorporation of Cs/HGQDs thin film with surface plasmon resonance spectroscopy produced positive responses towards the Fe3+ ion solutions of different concentration and it was found that Cs/HGQDs thin film able to detect Fe3+ as low as 0.5 ppm with a sensitivity of 0.11396° ppm−1. Subsequently, Cs/HGQDs layer have high potential as sensing layer to detect Fe3+ due to high affinity of Fe3+ ion towards the thin film with a value of binding affinity constant, K equals to 5.79 ppm−1. Atomic force microscopy was used to observe the surface morphology of the thin film and the result indicates that the thin film is relatively smooth and homogenous which also confirmed the interaction of Fe3+ with the thin film. Thus, Cs/HGQDs thin film shows potential for the detection of Fe3+ in solution.