Single-crystal TiO2/SrTiO3 core–shell heterostructured nanowire arrays for enhanced photoelectrochemical performance  

作　　者：Ying Chen Shi Li Ruo-Yu Zhao Wei Li Zhao-Hui Ren Gao-Rong Han 

机构地区：[1]State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Cyrus Tang Center for Sensor Materials and Application, Zhejiang University

出　　处：《Rare Metals》2019年第5期369-378,共10页稀有金属（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (Nos. 51232006, 51472218 and 11474249);the National Basic Research Program of China (No. 2015CB654900)

摘　　要：Vertically aligned TiO2/SrTiO3 core–shell heterostructured nanowire arrays with different shell thicknesses(5–40 nm)were fabricated on fluorine-doped tin oxide substrate via a hydrothermal process.Microstructural characterization demonstrated that the TiO2 nanowires were uniformly coated by the singlecrystal SrTiO3 shell,where continuous and large-area interface could be clearly observed.By this means,significantly enhanced photoelectrochemical water splitting properties(0.78 mA·cm^-2 at 1.23 V vs.RHE)were successfully realized in well-designed sample(with a shell thickness of 5–10 nm)compared with those of pristine TiO2(0.38 mA·cm^-2 at 1.23 V vs.RHE).The improvement of photoelectrochemical properties was attributed to the improved charge injection and charge separation,which are calculated by the results of water oxidation and sulfite oxidation measurements.Based on these results,a mechanism was proposed that SrTiO3 shell acted as an electron–hole separation layer to improve the photocurrent density.On the other hand,the sample with an over-thick SrTiO3 shell(20–40 nm)exhibited slightly reduced photoelectrochemical properties(0.66 mA·cm^-2),which could be explained by the increase of the recombination rate in thethicker SrTiO3 shell.This work provided a facile strategy to improve and modulate the photoelectrochemical performance of heterostructured photoanodes.Vertically aligned TiO2/SrTiO3 core–shell heterostructured nanowire arrays with different shell thicknesses（5–40 nm） were fabricated on fluorine-doped tin oxide substrate via a hydrothermal process.Microstructural characterization demonstrated that the TiO2 nanowires were uniformly coated by the singlecrystal SrTiO3 shell, where continuous and large-area interface could be clearly observed. By this means, significantly enhanced photoelectrochemical water splitting properties（0.78 mAácm-2 at 1.23 V vs. RHE） were successfully realized in well-designed sample（with a shell thickness of 5–10 nm） compared with those of pristine TiO2（0.38 mAácm-2 at 1.23 V vs. RHE）. The improvement of photoelectrochemical properties was attributed to the improved charge injection and charge separation, which are calculated by the results of water oxidation and sulfite oxidation measurements. Based on these results, a mechanism was proposed that SrTiO3 shell acted as an electron–hole separation layer to improve the photocurrent density.On the other hand, the sample with an over-thick SrTiO3 shell（20–40 nm） exhibited slightly reduced photoelectrochemical properties（0.66 mAácm-2）, which could be explained by the increase of the recombination rate in thethicker SrTiO3 shell. This work provided a facile strategy to improve and modulate the photoelectrochemical performance of heterostructured photoanodes.

关 键 词：TiO2/SrTiO3 heterostructured nanowire arrays PHOTOELECTROCHEMICAL water splitting SHELL thickness Band alignment 

分 类 号：TB383.1[一般工业技术—材料科学与工程] O646[理学—物理化学]