In-situ formation of electron acceptor to inhibit charge separation of photo-electrochemical sensor of dopamine-based CdS/Au/GQDs

•In-situ formation of PDA occurs on CdS/Au/GQDs electrode in a weak alkaline solution.•Abundant of electron acceptors groups in PDA has reduced the photocurrent signal.•The photocurrent decreased when the DA concentration increased in a range 0.1–350 µM.•The indirect detection of DA shows the lowest...

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Bibliographic Details
Published in:Electrochimica acta 2020-11, Vol.360, p.137013, Article 137013
Main Authors: Ibrahim, Izwaharyanie, Lim, Hong Ngee, Huang, Nay Ming
Format: Article
Language:English
Subjects:
Benzoquinone
Cadmium sulfide
CdS/Au/GQDs photoelectrode
Chemical sensors
Dopamine
Electron acceptor
Electrons
Graphene
Photo-electrochemical (PEC) sensor
Photoelectric effect
Photoelectric emission
Photoelectrons
Poly(dopamine)
Quantum dots
Sensors
Separation
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Summary:•In-situ formation of PDA occurs on CdS/Au/GQDs electrode in a weak alkaline solution.•Abundant of electron acceptors groups in PDA has reduced the photocurrent signal.•The photocurrent decreased when the DA concentration increased in a range 0.1–350 µM.•The indirect detection of DA shows the lowest LoD of 0.0078 μM.•CdS/Au/GQDs exhibits 1-fold lower LoD than the amount of DA in biological tissue. A versatile photo-electrochemical (PEC) sensor protocol was established to quantitatively monitor dopamine (DA) levels by utilizing a triple interconnected structure of cadmium sulfide (CdS) modified with gold and graphene quantum dots (Au/GQDs). The introduction of Au and GQDs on the photocatalytic active center of CdS act as a charge separation mediator and photosensitizer, respectively, which are favorable for charge separation and transportation and PEC conversion. When the CdS/Au/GQDs photoelectrode was utilized for DA sensing in a weak alkaline solution, DA was oxidized and converted to poly(dopamine) (PDA), which possesses abundant benzoquinone (BQ) groups that act as electron acceptors. Consequently, the electron acceptors formed in-situ on the surface of the photoelectrode, reducing the anodic photocurrent signal. Under the optimal conditions, the photocurrent decreased when the DA concentration increased in a dynamic working range from 0.1 to 350 µM and with a limit of detection (LoD) of 0.0078 μM. Herein, the proposed strategy involving photoelectron transfer between the electron acceptor and semiconductor provides a new and versatile protocol for PEC sensor development. [Display omitted]
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2020.137013