Synthesis of Magnetite-Semiconductor-Metal Trimer Nanoparticles through Functional Modular Assembly: A Magnetically Separable Photocatalyst with Photothermic Enhancement for Water Reduction

Hybrid nanoparticles have intrinsic advantages to achieve better activity in photocatalysis compared to single component materials, as it can synergistically combine functional components, which promote light absorption, charge transportation, surface reaction, and catalyst regeneration. Through functional modular assembly, a rational and stepwise approach has been developed to construct Fe3O4-CdS-Au trimer nanoparticles and its derivatives as magnetically separable catalysts for photothermo-catalytic hydrogen evolution from water. In a typical step-by-step synthetic process, Fe3O4-Ag dimers, Fe3O4-Ag2S dimers, Fe3O4-CdS dimers, and Fe3O4-CdS-Au trimers were synthesized by seeding growth, sulfuration, ion exchange, and in situ reduction consequently. Following the same reaction route, a series of derivative trimer nanoparticles with alternative semi-conductor and metal were obtained for water-reduction reaction. The experimental results show that the semiconductor acts as an active component for photocatalysis, the metal nanoparticle acts as a cocatalyst for enhancement of charge separation, and, the Fe3O4 component helps in the convenient separation of catalysts in magnetic-field and improves photocatalytic activity under near-infrared illumination due to photothermic effect.