Hierarchical TiO2/SnS2 heterostructure film with enhanced photoelectrochemical performance for self-powered photodetectors

Photoelectrochemical-type photodetectors have attracted extensive attention due to their simple and low-cost fabrication process, without external power sources, high photoresponsivity and fast response speed. Heterostructures can efficiently enhance interfacial carrier transfer and improve the photoelectrochemical performance of the photoelectrode. In this work, two-dimensional TiO2 nanosheets array film exposed {001} facets was firstly synthesized on fluorine -doped tin oxide conductive glass by hydrothermal method. Subsequently, a SnS2 nanoflakes layer was fabricated by chemical bath deposition to form a SnS2/TiO2 composite film considering band alignment and structural design. The morphology, composition and structure of the composites film were characterized. Under simulated sunlight irradiation, the photocurrent density of the SnS2/TiO2 heterojunction photoanode significantly increased to 1.3 mA/cm2, which is approximately 4.7 times and 2.6 times larger than that of the pristine SnS2 and TiO2 film, respectively. Moreover, the photoresponsivity of SnS2/TiO2 composite film reaches up to 12.44 mA/W. The boosted photoelectrochemical performance of SnS2/TiO2 PEC-type photodetectors can be mainly attributed to synergistic effect resulting from efficient light utilization and efficient charge transfer at the interface between SnS2 and TiO2. This work provides new insights for designing twodimensional optoelectronic and photoelectrochemical devices with improved performance through heterostructure construction.