A non-enzymatic photoelectrochemical sensor based on Co-Pi modified one-dimensional titanium oxide embedded microscale reactor

Abstract

Photoelectrochemical (PEC) sensing systems are promising candidates for detecting low concentrations of biological molecules; they are particularly encouraging when offered in a non-enzymatic format. A pitfall of non-enzymatic PEC sensors is their specificity. This, however, is often resolved by utilizing inorganic nanocatalyst. Here, we describe a novel non-enzymatic sunlight-driven PEC sensor based on cobalt phosphate (Co-Pi) deposition on a one-dimensional titanium dioxide (1D-TiO2) nanorod array for the ultra-low detection of glucose. The 1D-TiO2 nanorod array was prepared through a simple hydrothermal method and modified with Co-Pi using photo-assisted electrodeposition. The result was a microscale fluidic reactor. The modified electrodes with various Co-Pi thicknesses photocatalyst were characterized through a variety of techniques, including HRTEM, XRD, UV–vis spectroscopy, electrochemical impedance spectroscopy, and chronoamperometry. The characterization methods served to study and confirm the optimal electrode structure. The novel 1D-TiO2/Co-Pi electrode exhibited enhanced absorbance in the visual range of the nanorods with increased photoactivity and no drastic modification of the array’s surface. The PEC sensor microscale reactor exhibited a low limit of detection of 0.031 nM and a high sensitivity of 900 μA mM−1 cm−2 over a linear range of 0.1–10000 nM, demonstrating ultrasensitive detection of glucose. Overall, the surface modification of TiO2 by Co-Pi improved the sensor properties resulting in high selectivity, high stability, and high reproducibility.