CuInS2/Sb2S3 heterostructure modified with noble metal co-catalyst for efficient photoelectrochemical water splitting

In order to improve the water splitting efficiency of CuInS2 in a photoelectrochemical (PEC) cell, the novel CuInS2/Sb2S3 heterostructure photocathodes modified with Pt noble metal co-catalyst were prepared on the ITO substrate by the hydrothermal and electrochemical deposition method for the first time. The mechanism of the synthesis reaction for the CuInS2/Sb2S3 and CuInS2/Sb2S3/Pt were investigated. With the photoelectrochemical measurements, the photocurrent density of CuInS2/Sb2S3/Pt photoelectrode (−2.48 mA/cm2 at −0.6 V vs. RHE) is about 3.13 times relatively higher than that of the corresponding the pure CuInS2 photoelectrode (−0.79 mA/cm2 at −0.6 V vs. RHE). The excellent PEC behaviors profit from the modification by Sb2S3 that forms the heterostructure which broadens the response of visible light and increases the separation and transfer of photo-generated carriers. Moreover, after introducing Pt co-catalyst onto the surface of CuInS2/Sb2S3 photoelectrode, photo-generated electrons can be captured quickly which further effectively promotes the separation of photo-generated carriers and greatly improve the PEC performance. This work manifests that the structure of CuInS2/Sb2S3/Pt photocathodes has a guiding suggestion to provide a promising approach to designing a highly stabilized efficient device for photoelectrochemical water splitting.