RESUMO
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-2at 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.
RESUMO
The effect of lead sulfide (PbS) quantum dots (QDs) on the photoelectrochemical properties of TiO2 with a varied number of SILAR cycles has been investigated. The study has also highlighted physical processes including band alignment, charge recombination and transportation for a PbS QDs/TiO2 interface. The inclusion of PbS QDs underneath TiO2 thin film has significantly enhanced the PEC response due to a higher number of photogenerated charge carriers along with the efficient separation and facilitation of these carriers towards their respective electrodes. The uniqueness of the work lies in the high stability of the system as PbS QDs lie beneath the TiO2 thin film, compared to the commonly used QDs sensitization over metal oxide, along with a good photoresponse.