Switchable synthesis of p- and n-type Cu-In-S grooved pyramid-like microcrystals for unassisted photoelectrochemical water splitting
Abstract
Herein, p- and n-type switchable Cu-In-S microcrystals with grooved pyramid-like morphology are facilely synthesized by transforming binary In2S3. A cation exchange and in-situ growth mechanism is proposed to illustrate the generation of grooved pyramid-like Cu-In-S samples. It is demonstrated that the structure, composition, and semiconducting property of Cu-In-S films could be controlled by maneuvering the rate of cation exchange, which can be simply adjusted by varying the amount of sulfur precursor. With the increased amount of added thiourea, p-type CuInS2, n-type CuIn5S8, as well as the mixture of CuInS2 and CuIn5S8 are prepared. The p-type CuInS2 and n-type CuIn5S8 photoelectrodes respectively exhibit a cathodic photocurrent of -0.18 mA·cm-2 at -0.4 V vs. RHE and an anodic photocurrent of 0.61 mA·cm-2 at 0.7 V vs. RHE in 0.1 M Na2SO4 solution (pH=3) under AM 1.5G illumination. More importantly, an unassisted water splitting system using parallel mode composed of CoOx/CuIn5S8 photoanode and Pt/CuInS2 photocathode is constructed, which shows a photocurrent density of 0.015 mA·cm-2. The present work could provide a new idea for constructing efficient unassisted photoelectrochemical water splitting devices using copper-based chalcogenides. Meanwhile, the capability to switch p-n semiconducting properties has a great inspiration to enable the development of novel semiconductor materials for photoelectric applications.
