1D/2D/0D Mixed-Dimensional TiO2/ZnO/Ag Core–Shell Nanowires for High-Performance UV–Vis Photoelectrochemical Photodetectors

Abstract

One-dimensional (1D) TiO2 nanowires (NWs) have potential applications in photoelectrochemical (PEC) photodetectors due to their unique 1D geometries and optical and electrical properties. However, the wide bandgap and insufficient surface area of TiO2 NWs hinder their response spectra and responsivity. Constructing mixed-dimensional heterostructures may improve their PEC performance by controllably tuning the structure and properties of materials with different dimensionalities. In this strategy, mixed-dimensional TiO2/ZnO/Ag core–shell NWs were prepared by employing 1D TiO2 NWs with exposed {001} facets, 2D ZnO nanosheets (NSs), and 0D Ag quantum dots (QDs). The mixed-dimensional NW-based PEC photodetector exhibited a high responsivity (R = 730 and 490 mA/W) and a fast response speed (τr/τd = 1.10/0.91 and 1.52/0.61 s), with a broad response from the ultraviolet (380 nm) to visible (420 nm) region. The localized surface plasmon resonance of the 0D Ag QDs and unique type-II band alignment of 1D TiO2 NWs/2D ZnO NSs enhanced the light absorption and also the generation and separation of photogenerated carriers. These combined effects greatly enhanced the photodetector’s performance, showing that this approach can be used to fabricate mixed-dimensional heterostructures for high-performance optoelectronic devices.