Construction of TiO2@ZnO nanofibers with beads-on-a-string heterostructures for photoelectrochemical detection of lactic acid

Abstract

Photoelectrochemical sensing is a promising solution for health monitoring and food safety guarantee, and developing novel strategies for the facile preparation of advanced photoelectrochemical sensors is challenging. In this work, we report a novel strategy for preparing TiO2 nanofibers threaded ZnO heterostructures and the selective photoelectrochemical detection of lactic acid. Cascade electrospinning and hot-pressing technologies were employed to prepare TiO2 nanofibers threaded ZIF-8 precursor, and subsequent pyrolysis of ZIF-8 nanocrystals afforded beads-on-a-string heterostructures of TiO2@ZnO. The bead-like TiO2@ZnO heterostructures exhibit significantly enhanced charge transfer activity, photocurrent density and the smallest overpotential compared against that of ZnO and TiO2. The resultant photoelectrochemical sensors demonstrate a low detection limit of 0.031 μM, a high sensitivity of 29.18 μA mM−1, a wide linear range between 0.1 and 1.0 mM, and excellent reproducibility. Furthermore, GC-MS and in situ FTIR studies confirm the mechanistic pathway of photoelectrochemical oxidation. This work provides a facile strategy for developing MOFs derived heterostructures, and advances in various high performance photoelectrochemical applications could be envisioned.