CuInS<sub>2</sub> Nanosheet Arrays with a MoS<sub>2</sub> Heterojunction as a Photocathode for PEC Water Splitting
Mohit Kumar, Bhagatram Meena, Palyam Subramanyam, Govind Ummethala, Sairam K. Malladi, Shourya Dutta‐Gupta, Challapalli Subrahmanyam
Abstract
Developing cost-effective noble metal-free co-catalysts as alternatives to platinum group metals is an impeccable strategy to enhance photoelectrochemical (PEC) water splitting. In this report, we successfully fabricated CuInS 2 nanosheet array-based photocathode modified with CdS and co-catalyst MoS 2 in a green approach to improve water splitting under solar irradiation. The visible light absorption of the modified hybrid photocathode (CIS/CdS/MoS 2 ) was significantly enhanced due to introducing CdS and MoS 2 . Photoluminescence, impedance spectroscopy, and Mott–Schottky analysis depicted improved separation of excited electron–hole pairs, minimized resistance of charge transfer, and increased excited-state charge carrier concentration, resulting in increased photocurrent. Typical results indicated that composite photoelectrodes delivered higher photocurrent (−1.75 mA/cm 2 at 0 V vs RHE) and HC-STH conversion efficiency (0.42% at 0.49 V vs RHE) than those of CIS and CIS/CdS photoelectrodes. This improved PEC performance is accredited to the synergetic impact of CdS in charge generation and transfer and MoS 2 as a cocatalyst with active surface sites for proton reduction. This study not only reveals the promising nature of CuInS 2 -based light absorber photocathodes for solar energy utilization but also recommends the use of MoS 2 as a cocatalyst for the proton reduction reactions for widespread applications in solar to hydrogen conversion.