Chen, Z.

Guo, W.

Kübel, C.

Neumann, T.

Pfleging, W.

Redel, E.

Shekhah, O.

Welle, A.

Wenzel, W.

Wöll, C.

Yang, C.

English

KITopen

Bi2O3 nanoparticles encapsulated in surfacemounted metal–organic framework thin films†Wei Guo,a Zhi Chen,b Chengwu Yang,a Tobias Neumann,b Christian Kübel,b,cWolfgang Wenzel,b Alexander Welle,a,c Wilhelm Pfleging,c,d Osama Shekhah,eChristof Wölla and Engelbert Redel*aWe describe a novel procedure to fabricate a recyclable hybrid-photocatalyst based on Bi2O3@HKUST-1 MOF porous thin films.Bi2O3 nanoparticles (NPs) were synthesized within HKUST-1(or Cu3(BTC)2) surface-mounted metal–organic frame-works(SURMOFs) and characterized using X-ray diffraction (XRD), a quartzcrystal microbalance (QCM) and transmission electron microscopy(TEM). The Bi2O3 semiconductor NPs (diameter 1–3 nm)/SURMOFheterostructures exhibit superior photo-efficiencies compared toNPs synthesized using conventional routes, as demonstrated via thephotodegradation of the nuclear fast red (NFR) dye.Photocatalysts carry huge potential for the removal of contami-nations from the environment and have been demonstrated toshow an impressive performance in decomposing organic pol-lutants under UV-light irradiation.1 Among the numeroussemiconducting materials under investigation, recently, muchattention has been given to Bi2O3 photocatalysts. Bi2O3exhibits narrow electronic band gaps (2.8 eV or less) andshows p-type behavior with high photocatalytic activity.2Straightforward applications, however, are hampered by thefact that the fabrication of monodisperse Bi2O3 nanoparticles(NPs) with well defined-diameters represents a major chal-lenge. Conventional NP synthesis methods typically yieldrather broad NP size distributions.3 For the fabrication of highperformance photocatalysts as well as for a more detailedunderstanding of the fundamental photocatalytic process, thedevelopment of a novel synthesis allowing the production ofBi2O3 clusters and NPs with narrow size distributions andlarge surface areas is urgently required.A very appealing strategy to attain this goal is the synthesisof NPs inside the voids of metal–organic frameworks (MOFs).4Since the pore-walls of the MOF can be used to control the sizeof the NPs, as a result of their pore sizes and large loadingcapacity for guest species, this class of highly porous, crystal-line materials provides an ideal platform for the encapsulationof catalytically active compounds (such as Pt,5 Au,6 Ti-based7)as well as of photosensitizers.8 MOFs are typically insulators,the size of the band-gap strongly depends on the nature of theorganic ligands used to build the molecular frameworks.9 Overthe past decade, an increasing number of studies have beenreported using MOFs as a host matrix, which after loadingwith appropriate compounds act as a high-yield photocatalystwith a number of interesting properties, e.g. for hydrogenevolution (Pt@MOF),5 light-driven α-alkylation reactions(BCIP@MOF)10 and enantiomer recognition and separation inchiral MOC@SURMOF.11The present work is based on a particular MOF, HKUST-1,which is grown in the form of thin, monolithic coatings onmodified Au substrates using liquid-phase epitaxy (LPE), yield-ing so-called SURMOFs, surface-mounted metal–organicframeworks. Liquid-phase epitaxy (LPE) is a quite attractivemethod for depositing MOFs in a layer-by-layer controlledfashion, yielding very homogeneous, highly oriented and crys-talline MOF thin films. SURMOFs can be manufactured withthicknesses ranging from the nanometer up to the micrometer-regime, and they allow for straightforward characterization oftheir mechanical,12 optical,13 photonic14 and optoelectronic15as well as their magnetic,16 electrical17 and electrochemical18properties. In addition, SURMOFs provide a direct path to thefabrication of MOF-based membranes,19 which is of profoundinterest also in the area of water purification.Here, we use the pores within the HKUST-1 SURMOFs forthe synthesis of Bi2O3 clusters/NPs, yielding a novel Bi2O3@HKUST-1 (or Cu3(BTC)2, BTC = 1,3,5-benzenetricarboxylic acid)hybrid-photocatalyst. The layer-by-layer strategy is used tofabricate this hybrid material. These final hybrid-photocata-aKarlsruhe Institute of Technology, Institute of Functional Interfaces (IFG), Hermann von Helmholtz Platz 1, 76344 Eggenstein Leopoldshafen, Germany.E mail: Engelbert.Redel@kit.edubKarlsruhe Institute of Technology, Institute of Nanotechnology (INT),Hermann von Helmholtz Platz 1, 76344 Eggenstein Leopoldshafen, Germany cKarlsruhe Institute of Technology, Karlsruhe Nano Micro Facility (KNMF), Hermann von Helmholtz Platz 1, 76344 Eggenstein Leopoldshafen, Germany dKarlsruhe Institute of Technology, Institute of Advanced Materials (IAM), Hermann von Helmholtz Platz 1, 76344 Eggenstein Leopoldshafen, Germany eAdvanced Membranes and Porous Materials Center, King Abdulah University of Science and Technology, Kingdom of Saudi Arabia† Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00532b

Bi₂O₃ nanoparticles encapsulated in surface mounted metal-organic framework thin films

https://publikationen.bibliothek.kit.edu/1000054525/149905485

Bi₂O₃ nanoparticles encapsulated in surface mounted metal-organic framework thin films

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