Abstract
The hierarchical nanostructured CdS@MoS2 core shell was architectured using template free facile solvothermal technique. More significantly, the typical hexagonal phase of core CdS and shell MoS2 has been obtained. Optical study clearly shows the two steps absorption in the visible region having band gap of 2.4 eV for CdS and 1.77 eV for MoS2. The FESEM of CdS@MoS2 reveals the formation of CdS microsphere (as a core) assemled with 40–50 nm nanoparticles and covered with ultrathin nanosheets of MoS2 (Shell) having size 200–300 nm and the 10–20 nm in thickness. The overall size of the core shell structure is around 8 µm. Intially, there is a formation of CdS microsphre due to high affinity of Cd ions with sulfur and further growth of MoS2 thin sheets on the surface. Considering band gap ideally in visible region, photocatalytic hydrogen evolution using CdS@MoS2 core shell was investigated under natural sunlight. The utmost hydrogen evolution rate achieved for core shell is 416.4 µmole h−1 with apparent quantum yield 35.04%. The photocatalytic activity suggest that an intimate interface contact, extended visible light absorption and effective photo generated charge carrier separation contributed to the photocatalytic enhancement of the CdS@MoS2 core shell. Additional, the enhanced hole trapping process and effective electrons transfer from CdS to MoS2 in CdS@MoS2 core shell heterostructures can significantly contribute for photocatalytic activity. Such core shell heterostructure will also have potential in thin film solar cell and other microelectronic devices.
Highlights
The transition metal chalcogenide semiconductor catalyst such as CdS reported as one of the promising semiconductor catalyst for hydrogen generation due to its narrow band gap 2.4 eV, proper valence band position and excellent stability[15,16]
The conduction band edge of CdS is more negative than the reduction potential of H+/H2, making it more suitable for the H2 generation[17,18]
The experimental and computational results disclosed that the edges of ultrathin MoS2 nanosheets act as an active sites for the photocatalytic H2 generation[25]
Summary
The transition metal chalcogenide semiconductor catalyst such as CdS reported as one of the promising semiconductor catalyst for hydrogen generation due to its narrow band gap 2.4 eV, proper valence band position and excellent stability[15,16]. The experimental and computational results disclosed that the edges of ultrathin MoS2 nanosheets act as an active sites for the photocatalytic H2 generation[25]. Yan et al demonstrated the CdS/MoS2 core shell nano rod synthesis for efficient hydrogen production by a facile chemical deposition method[19]. CdS@MoS2 core shell fabrication was demonstrated by simple solvothermal route. The hierarchical heterostructures of few layered ultrathin nanosheets of MoS2 uniformly grown on the surface of CdS microsphere is demonstrated. The as-prepared CdS@MoS2 core shell heterostructures show much higher photocatalytic activity and better stability toward water splitting compared with pristine CdS and MoS2 under natural solar light. Our superior photocatalytic hydrogen generation results suggest CdS@MoS2 core shell is promising cost effective photocatalyst for the clean energy fuel
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