Hierarchical assembly of TiO2-SrTiO3 heterostructures on conductive SnO2 backbone nanobelts for enhanced photoelectrochemical and photocatalytic performance.

Heterostructures can play a role in enhanced photoinduced electrochemical and catalytic reactions due to the advantageous combination of two compounds. Herein, we demonstrate the fabrication of Sb:SnO2@TiO2-SrTiO3 3D heterostructures via a simple hydrothermal method using a conductive Sb:SnO2@TiO2 nanobelt electrode as a template. XRD, FESEM, and TEM analyses confirm that a well-dispersed and crystalized SrTiO3 layer is formed on the surface of TiO2 nanorods. The photoelectrochemical (PEC) performance of the heterostructure is optimized by controlling the reaction time. Details about the effect of the hydrothermal reaction time on the PEC performance are discussed. The optimized Sb:SnO2@TiO2-SrTiO3 heterostructure exhibited a higher onset potential and a saturated photocurrent in comparison to the Sb:SnO2@TiO2 nanostructure. The result is attributed to a Fermi level shift and a blocking layer effect caused by the SrTiO3. Furthermore, the photocatalytic degradation of methylene blue was significantly enhanced on the optimized Sb:SnO2@TiO2-SrTiO3. This work demonstrates that a synergetic effect between three-dimensional nanoarchitecturing and a heterojunction structure is responsible for enhanced PEC as well as improved photocatalytic performance levels, both of which can be extended to other metal-oxide and/or ternary compounds.