Novel synthesis of graphene oxide/In2S3/TiO2 NRs heterojunction photoanode for enhanced photoelectrochemical (PEC) performance

Novel heterostructure photocatalyst built from titanium dioxide (TiO2), graphene oxide (GO) and indium sulfide (In2S3) has been successfully prepared for photoelectrochemical hydrogen production. The stepwise introduction of three materials on conductive glass substrate has been realized through hydrothermal, electrochimical and spin coating deposition methods, respectively. The structure, morphology, composition, optical and photoelectrochemical properties of the resultant photoanodes were investigated in detail. The presence of GO in the heterostructure film was confirmed by Raman analysis with D and G band intensity. Surface morphology analysis of the GO/In2S3/TiO2 NRs structure reveal the homogenous distribution of graphene oxide on In2S3/TiO2 NRs surface. From UV–Vis analysis, band gap energy of the samples decreases gradually from 3.34 eV (TiO2 NRs) to 3.12 eV, with In2S3 and GO addition. The electrochemical impedance spectroscopy (EIS) further confirmed that GO/In2S3/TiO2NRs heterostructure possessed the lowest charge-transfer resistance, revealing that In2S3 and GO could significantly accelerate the electron mobility compared with bare TiO2. From Mott-Schottky plots, several parameters such as flat-band potential and free carrier concentration were determined. Next, The GO/In2S3/TiO2 NRs electrode achieved remarkably improved current density (0.45 mAcm2 at 0.8 V vs Ag/AgCl) compared to pure TiO2 NRs or In2S3/TiO2 NRs electrodes, which attributes to the uniform structure and excellent electrical conductivity of GO, which could reduce the combination rate of the photo electron-hole pairs. These results reveal that GO/In2S3/TiO2 NRs possesses great potential toward the development of newly synthesizable catalysts in the field of photoelectrochemical water splitting.