Visible light driven CZTS QDs/α-Fe2O3-graphene p–n heterojunction for photoelectrochemical water splitting

Abstract This work investigates the implication of graphene and Cu2ZnSnS4 (CZTS) quantum dots (QDs) incorporation in the hematite thin film for its use in a photoelectrochemical cell. The thin film has been prepared by decorating the CZTS QDs over graphene-hematite composite by simple chemical approach. In Comparison to graphene modification and CZTS QDs modification separately over hematite thin film, the combination of both has produced more photocurrent. The photocurrent density obtained for CZTS QDs and graphene modified hematite thin film is 1.82 mA cm−2 at 1.23 V/RHE, which is 1.75 higher than pristine hematite. The presence of CZTS QDs over hematite-graphene composite enhances the absorption properties of composite along with creating the p–n junction heterostructure which aids the transportation of the charge carriers. The thin films have been characterized using x-ray diffractometer, Raman spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy, and diffuse reflectance UV–vis spectroscopy for phase, morphology and optical properties analysis. The enhancement in photoresponse has been justified by Mott-Schottky and transient open circuit potential analysis.