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Novel Visible-Light-Driven Photocatalysts for Efficient Hydrogen Generation: Hybrid Composites of Ti-Based MOF and Low-Dimensional Nanoparticles

Wednesday, 3 October 2018
Universal Ballroom (Expo Center)
T. W. Kim, M. Sohail, and H. Kim (Korea Institute of Energy Research (KIER))
A novel visible-light-driven photocatalyst, hybrid composites of MIL-125-NH2(Ti-MOF) and low-dimensional nanostructures(i.e, 0D CdS nanoparticles (NPs) and 2D ZnCr-LDH nanosheets(NSs)), has been developed for H2 generation from water under visible light irradiation. For synthesis, ZnCr-LDH and CdS nanoparticles are first prepared according to the previous studies. The hybrid composites was synthesized by growing Ti-MOF in a colloidal suspension of ZnCr-LDH NSs or CdS NPs under solvothermal reaction. The obtained hybrid composites were systematically characterized by various tools such as powder XRD, XAFS, FESEM, TEM/EDX, BET, UV-Vis, and so on. In case of hybrid composites of Ti-MOF/ZnCr-LDH NSs, according to powder XRD and FESEM, the crystallinity and morphology of Ti-MOF after the hybridization with ZnCr-LDH NSs became lower and irregular in comparison with pure Ti-MOF. This result implies that ZnCr-LDH NSs limit the crystal growth of Ti-MOF. The hybrid composites were performed photocatalytic test for H2 generation under visible light irradiation (λ≥420 nm). From the test, we found that the hybrid material has a photocatalytic performance for hydrogen generation much better than each component. More interestingly, in this work the highly efficient H2 production of the present hybrid material was achieved without a co-catalyst such as Pt. Through deep investigations using XPS, PL, and electrochemical analyses, we found that the improved photocatalytic activity results from the increase of the lifetime of the photoinduced electrons and holes by strong coupling of two components and their proper band alignment. In addition, hybridization of Ti-MOF with ZnCr-LDH NSs or CdS NPs improves a photo- and chemical stability compared to each component before hybridization. In this work, we will discuss in detail about synthesis procedure, structural formation, photocatalytic ability, and mechanism for the present hybrid composites.