Direct Z-Scheme Heterostructure of Vertically Oriented SnS2 Nanosheet on BiVO4 Nanoflower for Self-Powered Photodetectors and Water Splitting.

ABSTRACT

The construction of nanostructured Z-scheme heterostructure is a powerful strategy for realizing high-performance photoelectrochemical (PEC) devices such as self-powered photodetectors and water splitting. Considering the band structure and internal electric field direction, BiVO4 is a promising candidate to construct SnS2 -based heterostructure. Herein, the direct Z-scheme heterostructure of vertically oriented SnS2 nanosheet on BiVO4 nanoflower is rationally fabricated for efficient self-powered PEC photodetectors. The Z-scheme heterostructure is identified by ultraviolet photoelectron spectroscopy, photoluminescence spectroscopy, PEC measurement, and water splitting. The SnS2 /BiVO4 heterostructure shows a superior photodetection performance such as excellent photoresponsivity (10.43 mA W-1 ), fast response time (6 ms), and long-term stability. Additionally, by virtue of efficient Z-scheme charge transfer and unique light-trapping nanostructure, the SnS2 /BiVO4 heterostructure also displays a remarkable photocatalytic hydrogen production rate of 54.3 µmol cm-2 h-1 in Na2 SO3 electrolyte. Furthermore, the synergistic effect between photo-activation and bias voltage further improves the PEC hydrogen production rate of 360 µmol cm-2 h-1 at 0.8 V, which is an order of magnitude above the BiVO4 . The results provide useful inspiration for designing direct Z-scheme heterostructures with special nanostructured morphology to signally promote the performance of PEC devices.