A one-step hydrothermal route to fabricate a ZnO nanorod/3D graphene aerogel-sensitized structure with enhanced photoelectrochemistry performance and self-powered photoelectrochemical biosensing of parathion-methyl

Abstract

Developing a new functional sensitized structure for improving the inherent property of photoactive materials and selecting an efficient electron donor as a photoelectrochemical (PEC) signal amplification strategy are crucial for achieving excellent PEC biosensors. Herein, we present a facile one-pot hydrothermal strategy for fabricating ZnO nanorod-decorated 3D graphene aerogels (ZnO/GAs). In this nanoarchitecture, GAs act as a new generation enhanced carrier, which can effectively improve the photoactivity of ZnO under visible light by enhancing the interfacial charge transfer. In addition, the as-prepared ZnO/GA nanocomposites exhibited two times higher photocurrent intensity than that of ZnO/graphene. Furthermore, we developed a novel self-powered PEC biosensor based on a ZnO/GAs sensitized structure with the amplification of enzymolysis products for the detection of parathion-methyl. Thiocholin, as a sacrificial electron donor, which is produced from the hydrolysis of acetylthiocholine catalyzed by acetylcholinesterase (AChE), can further significantly improve the photocurrent. Then, the inhibition of AChE activity by parathion-methyl prevented the production of thiocholine, resulting in an obvious decrease in photocurrents. Based on the above results, we fabricated an AChE-based self-powered PEC biosensor for the sensitive and selective determination of parathion-methyl with a linear range of 0.1 ng mL⁻¹ to 0.1 μg mL⁻¹ and a detection limit of 0.03 ng mL⁻¹ (S/N = 3). This PEC biosensing strategy not only gives insights into using GAs as a novel sensibilizer to improve the PEC nature of semiconductors but also provides a promising flexible platform for organophosphorus pesticide detection.