Bandgap-energy-adjustable noble-metal-free MoS2-ZnxCd1-xS for highly efficient H2 production under visible-light

Background: Recognized for its high calorific value, clean and non-polluting properties, hydrogen is considered to be one of the most attractive solutions to the impending energy crisis. Photocatalytic water splitting has been widely investigated for its promise to produce hydrogen in a sustainable, environmentally friendly and low-cost approach. In pursuit of high photocatalytic efficiency, multiple strategies haven been explored such as doping, co-catalyst modification and heterojunction construction realizing promising improvements. Methods: We synthesized CdS doped with Zn ions and modified with MoS2 as co-catalyst to form ZnxCd1-xS solid solution and MoS2-Zn0.25Cd0.75S heterojunction using a simple one-step hydrothermal method. The synthesized catalyst was used water splitting under visible light irradiation. The structural and morphological characteristics of these materials, along with their photocatalytic mechanisms, were investigated using multiple techniques such as SEM, TEM, XPS, PL, etc. Findings: The photocatalyst consisting of 0.9 wt.% MoS2-Zn0.25Cd0.75S achieved a production rate of 6276 mu mol h-1 g-1, which is 17.4 times higher than that of pure CdS and 1.6 times higher than that of Zn0.25Cd0.75S. The composite also demonstrated a high apparent quantum yield of 11.1 % at 420 nm. The mechanism of the water splitting process, revealed through various techniques, introduces novel pathways for crafting high-efficiency photocatalysts with an internal electron-hole separation heterostructure.