A real-time on-line photoelectrochemical sensor toward chemical oxygen demand determination based on field-effect transistor using an extended gate with 3D TiO2 nanotube arrays

• Published in: Sensors and actuators. B, Chemical Chemical, 2019-06, Vol.289, p.106-113
• Main Authors: Si, Hewei, Pan, Nengqian, Zhang, Xidong, Liao, Jianjun, Rumyantseva, M.N., Gaskov, A.M., Lin, Shiwei
• Format: Article
• Language: English
• Subjects: 3D TiO2 nanotube arrays; Change detection; Chemical oxygen demand; Chemical oxygen demand (COD); Chromates; Continuous flow; Extended-gate field-effect transistor; Field effect transistors; Flow velocity; Nanoparticles; Nanotubes; Organic chemistry; Photoelectrochemical sensor; Quality assessment; Real time; Real-time on-line detection; Reproducibility; Semiconductor devices; Stability analysis; Titanium dioxide; Transistors; Variations; Water quality
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2019.03.071

[Display omitted] •A photoelectrochemical sensor based on extended-gate FET was proposed with a 3D Pt-NPs/TNTAs/Ti sensing electrode.•A photoelectrochemical thin-layer reactor was designed for real-time on-line COD determination.•Low detection limit of 0.12 mg/L COD and wide linear range from 1.44 to 672 mg/L at a flow rate of 1.0 mL/s were obtained.•An onsite measurement technique especially suits for COD slight fluctuations. Chemical oxygen demand (COD) is one of the most widely used parameters for water quality assessment. Quantification and detection of COD slight fluctuations is crucial for an early detection of abnormal change in the water environment. Here we report a real-time on-line photoelectrochemical method for sensitive COD detection using an extended-gate field-effect transistor (EGFET) sensor. The FET gate consists of a Ti mesh electrode with 3D TiO2 nanotube arrays modified by Pt nanoparticles. The device shows a COD detection limit down to 0.12 mg/L and a wide dynamic linear range from 1.44 mg/L to 672 mg/L at a continuous flow rate of 1.0 mL/s. The method reported also displays excellent stability, accuracy and reproducibility. More importantly, real water samples analyses with the proposed method are in a good agreement with the standard dichromate method. The results suggest that the EGFET-based photoelectrochemical sensors are potential candidates for practical COD onsite measurement.