Synthesis of α-Bi2Mo3O12/TiO2 Nanotube Arrays for Photoelectrochemical COD Detection Application.

One-dimensional anodic TiO2 nanotube arrays hold great potential as a photoelectrochemical sensor for the determination of chemical oxygen demand (COD). In this work, we report a warm synthesis of modified TiO2 nanotube arrays with enhanced photoelectrochemical determination performance. Herein, a bismuth-based semiconductor (α-Bi2Mo3O12) was introduced into TiO2 nanotube arrays by sequential chemical bath deposition (CBD) at room temperature. Field-emission scanning electron microscopy, X-ray diffraction, Raman, and X-ray photoelectron spectroscopy were used to investigate the morphologies, structures, and elemental analysis of the products. The photoelectrochemical properties of TiO2 and α-Bi2Mo3O12/TiO2 NTAs were measured by amperometry and cyclic votammetry methods. The α-Bi2Mo3O12/TiO2 nanotube arrays decrease the background photocurrent and increase the current response to organics at the same time, both of which are beneficial to enhancing the photoelectrochemical detection performance. The optimized α-Bi2Mo3O12/TiO2 NTAs with enhanced photoelectrochemical detection performance can achieve a detection sensitivity of 2.05 μA·cm-2/(mg·L-1) and a COD detection range of 0.366-208.9 mg/L respectively. With the α-Bi2Mo3O12 modification, the surface electrochemical reactions of TiO2 NTAs were regulated, the mechanisms of which were also further studied.