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.