Enhanced Photoelectrocatalytic and Photoelectrochemical Properties by High-Reactive TiO2/SrTiO3 Hetero-Structured Nanotubes with dominant {001} Facet of Anatase TiO2

Abstract

High-reactive TiO2 crystals with controllable facets have been widely investigated in photocatalysis, photoelectrocatalysis, solar energy conversion and other related fields due to their unique structure-dependent properties. In this work, high-reactive TiO2/SrTiO3 (TSr) hetero-structured nanotubes with dominant TiO2 {001} facet are fabricated in a Sr(OH)2 solution by varying the hydrothermal time, utilizing anodizing TiO2 nanotubes on a Ti substrate as both a “structure-directed” template and an initial reagent to obtain these hetero-structured composites. Based on XRD, FE-SEM with EDS, FE-TEM, XPS and Raman characterization, the high-reactive TSr hetero-structured nanotubes with dominant {001} facet of anatase TiO2 are definitely synthesized and well-dispersed, crystallized SrTiO3 are acquired on the surface of TiO2 nanotubes after the hydrothermal treatment. Compared with the reference TiO2 nanotubes, transient photocurrent (I-t) and open circuit voltage (V-t) measurements indicate that the photoelectrochemical properties of these resulting composites are distinctly enhanced by controlling the hydrothermal time to regulate SrTiO3 coverage on the surface of nanotubes. In particular, photoelectrocatalytic (PEC) degradation of “target molecules” MB are further implemented to evaluate their PEC activities, and these data reveal the significant improvement of their corresponding activities over the reference TNT2, and this TiO2/SrTiO3 composite with the hydrothermal time of 30min (TSr3) possesses the highest PEC rate of 99.93% for MB after the degradation of 20min. These above results are attributed to the high-reactive TiO2 {001} facet of TiO2/SrTiO3 interior and the hetero-structured interfaces by SrTiO3 generated on TiO2 nanotubes in a hydrothermal process. In addition, the mechanism of PEC degradation is also simply discussed in comparison to the relevant photocatalytic (PC) and electrocatalytic (EC) reaction. This work demonstrates that a synergetic mechanism between high-reactive {001} facet of anatase TiO2 and hetero-structured characteristics contributes to enhancing their PEC activities and according photoelectrochemical properties, which can be extended to other binary compounds with high-reactive facets.