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.