Three-Dimensional WO3 Nanoplate/Bi2S3 Nanorod Heterojunction as a Highly Efficient Photoanode for Improved Photoelectrochemical Water Splitting.

The rational design of semiconductor photoanodes with sufficient light absorption, efficient photogenerated carrier separation, and fast charge transport is crucial for photoelectrochemical (PEC) water splitting. Incorporating a small-band-gap semiconductor to a large-band-gap material with matched energy band position is a promising route to improve the light harvesting and charge transport. Herein, we report the fabrication of a three-dimensional heterojunction with uniform Bi2S3 nanorods on WO3 nanoplates by hydrothermal process and chemical bath deposition. The seed layer strategy was used to assist the growth of Bi2S3 nanorods for perfect interface contact between WO3 and Bi2S3. The as-prepared WO3/Bi2S3 composite exhibited a much enhanced photocurrent (5.95 mA/cm2 at 0.9 V vs reversible hydrogen electrode), which is 35 and 1.4 times higher than those of pristine WO3 and WO3/Bi2S3 composite without a seed layer, respectively. In addition, higher incident photon-to-current conversion efficiency (68.8%) and photoconversion efficiency (1.70%) were achieved. The enhancement mechanism was investigated in detail, and the sufficient light absorption, efficient charge transport, and high carrier density simultaneously contribute to the improved PEC activity. These findings will open up new opportunities to develop other highly efficient heterostructures as photoelectrodes for PEC applications.