Ultrasonication-assisted liquid-phase exfoliation enhances photoelectrochemical performance in α-FeO/MoS photoanode.

This study successfully manufactured a p-n heterojunction hematite (α-FeO) structure with molybdenum disulfide (MoS) to address the electron-hole transfer problems of conventional hematite to enhance photoelectrochemical (PEC) performance. The two-dimensional MoS nanosheets were prepared through ultrasonication-assisted liquid-phase exfoliation, after which the concentration, number of layers, and thickness parameters of the MoS nanosheets were respectively estimated by UV-vis, HRTEM and AFM analysis to be 0.37 mg/ml, 10-12 layers and around 6 nm. The effect of heterojunction α-FeO/MoS and the role of the ultrasonication process were investigated by the optimized concentration of MoS in the forms of bulk and nanosheet on the surface of the α-FeO electrode while measuring the PEC performance. The best photocurrent density of the α-FeO/MoS photoanode was obtained at 1.52 and 0.86 mA.cm with good stability at 0.6 V vs. Ag/AgCl under 100 mW/cm (AM 1.5) illumination from the back- and front-sides of α-FeO/MoS; these values are 13.82 and 7.85-times higher than those of pure α-FeO, respectively. The results of electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis showed increased donor concentration (2.6-fold) and decreased flat band potential (by 20%). Moreover, the results of IPCE, ABPE, and OCP analyses also supported the enhanced PEC performance of α-FeO/MoS through the formation of a p-n heterojunction, leading to a facile electron-hole transfer.