SnS2 Nanosheets/H‐TiO2 Nanotube Arrays as a Type II Heterojunctioned Photoanode for Photoelectrochemical Water Splitting

Improving the separation efficiency of photogenerated electron–hole pairs and the conductivity of electrons to photoanode substrates are critical to achieve high‐performance photoelectrochemical (PEC) water splitting. Here, a SnS2/H‐TiO2/Ti heterojunction photoanode was fabricated with SnS2 nanosheets vertically grown on hydrogen‐treated TiO2 (H‐TiO2) nanotube arrays on a Ti substrate. It showed a significantly enhanced photocurrent of 4.0 mA cm−2 at 1.4 V (vs. reversible hydrogen electrode) under AM 1.5 G illumination, 70 times higher than that of SnS2/TiO2/Ti. Kelvin probe force microscopy measurements indicated that photogenerated electrons could be easily transported through the SnS2/H‐TiO2 interface but not through the SnS2/TiO2 interface. Through hydrogen treatment, defects were created in H‐TiO2 nanotubes to convert type I junctions to type II with SnS2 nanosheets. As a result, a high efficiency of electron–hole separation at the SnS2/H‐TiO2 interface and a high electron conductivity in H‐TiO2 nanotubes were achieved and improved PEC performance. These findings show an effective route towards high‐performance photoelectrodes for water splitting.