Improved Interfacial Charge Transfer on Noble Metal-Free Biomimetic CdS-Based Tertiary Heterostructure @ 2D MoS2-CdS-Cu2O with Enhanced Photocatalytic Water Splitting

Abstract

High charge separation efficiency with a wide optical absorption window is the prime requirement for the scale up of a stable solar photocatalytic hydrogen generation process. A new noble metal-free heterostructure of 2D MoS2-CdS-Cu2O is designed by depositing cauliflower-shaped CdS and nanosized Cu2O on exfoliated 2D MoS2. Characterization by XPS, high-resolution transmission electron microscopy (HRTEM), and UV-visible spectra confirms the formation of nanosized Cu2O with desired interface formation with MoS2 sheet and CdS thus extending the optical absorption range up to 900 nm. Water splitting activity in the presence of lactic acid is found to be 7.89 and 11.53 mmol g(-1) h(-1) on MoS2-CdS and MoS2-CdS-Cu2O, respectively, with good repeatability under visible light. Efficient interfacial charge separation is manifested from demised photoluminescence (PL) intensity which supports the suppression of hole-electron recombination in the tertiary heterostructure. In addition, the formation of dual p-n junction as indicated from Mott-Schottky analysis further strengthen the faster electron and holes separation objective. Compared to the pure CdS, hydrogen efficiency is 20.96 times higher on a noble metal-free tertiary catalyst with an apparent quantum efficiency of 8.75%. Hopefully, the 2D material-based architecture of dual p-n junction with desired interface engineering will facilitate the catalyst design with increased water splitting activity under solar/visible light.