Reduced Graphene Oxide/MXene-Derived TiO2 Hybrid Interface Layer for the Improvement of Zinc Oxide Nanorod Growth and Their Applications in Glutathione Sensing

Photoelectrochemical (PEC) sensor is an important type of biosensor widely used in glutathione (GSH) sensing. The PEC properties of the photoanode present in the sensor are critical to its sensing performance. Zinc oxide (ZnO) is an excellent semiconductor with a suitable band gap and light absorption ability for photoanode applications. Meanwhile, the interfacial layer is also important in the separation and transportation process of the excitons. In this work, high-quality ZnO nanorods were grown on the indium tin oxide (ITO) substrates. An interfacial layer consisting of reduced graphene oxide (RGO) or MXene (a two-dimensional transition metal carbide)-derived TiO2 was introduced. Our results show that the introduction of the RGO/TiO2 hybrid interfacial layer can promote both the high-quality growth of ZnO nanorods and also provides suitable band gap grading for efficient excitons separation and transportation. The GSH sensing performance of the PEC sensor based on the ZnO nanorods grown on the RGO/TiO2 hybrid layer-coated ITO photoanode can dramatically improve the photocurrent strength and linearity.