In-Situ Growth and Immobilization of CdS Nanoparticles onto Functionalized MoS : Preparation, Characterization and Fabrication of Photoelectrochemical Cells.

A facile strategy for the controllable growth of CdS nanoparticles at the periphery of MoS en route the preparation of electron donor-acceptor nanoensembles is developed. Precisely, the carboxylic group of α-lipoic acid, as addend of the modified MoS obtained upon 1,2-dithiolane functionalization, was employed as anchor site for the in situ preparation and immobilization of the CdS nanoparticles in an one-pot two-step process. The newly prepared MoS /CdS hybrid material was characterized by complementary spectroscopic, thermal and microscopy imaging means. Absorption spectroscopy was employed to register the formation of MoS /CdS, by observing a broad shoulder centered at 420 nm due to CdS nanoparticles, while the excitonic bands of MoS were also evident. Moreover, based on the efficient quenching of the characteristic fluorescence emission of CdS at 725 nm by the presence of MoS , strong electronic interactions at the excited state between the two species within the ensemble were identified. Photoelectrochemical assays of MoS /CdS thin-film electrodes revealed a prompt, steady and reproducible anodic photoresponse during repeated on-off cycles of illumination. A significant zero-current photopotential of -540 mV and an anodic photocurrent of 1 μA were observed, underlining improved charge-separation and electron transport from CdS to MoS . The superior performance of the charge-transfer processes in MoS /CdS is of direct interest for the fabrication of photoelectrochemical and optoelectronic devices.