Three-Dimensional Titania Arrays Coupled with Dopamine for Visible-Light-Induced Photoelectrochemical Sensing

Abstract

Photoelectrochemical sensing signals are highly dependent on photoelectrodes. It is of great significance yet challenge to develop high-performance photoelectrodes to achieve reliable photoelectrochemical sensing signals and low detection limit, especially via simple methods. In this study, three-dimensional TiO2 hierarchical nanowire arrays with nanocavities were synthesized through a hydrogen peroxide-assisted wet chemical reaction followed by a facile liquid-phase deposition process. Subsequently, dopamine with enediol ligand was decorated on the TiO2 arrays by chelation. Reduced nicotinamide adenine dinucleotide and its oxidized form constitute a cofactor system of over 300 dehydrogenases, playing a crucial role in the biological systems. Therefore, it was used as a model target compound to evaluate the PEC sensing performances. The sensor presents a liner concentration range of 0.05–50 µM with a high sensitivity of 0.29 μA∙μM−1∙cm−2 and a low detection limit of 0.03 μM (the signal-to-noise ratio is 3). The excellent sensing performances can be attributed to the multiple advantages: the TiO2 hierarchical nanowire arrays with nanocavities provide abundant active sites for surface adsorption/reaction to increase photoconversion efficiency; coupling TiO2 with dopamine enhances the visible light harvesting capacity and regulates the charge transfer. This work demonstrates the feasibility of a 3D TiO2 array coupled with dopamine as a highly sensitive photoelectrode for the detection of nicotinamide adenine dinucleotide under visible light illumination. The findings can provide a new route to design high-performance 3D nanoarchitectures for PEC sensing applications in biomedical and environmental detections.

Keywords: PEC sensors, Titanium dioxide, 3D nanoarchitectures, Dopamine coupling, NADH detection