Hexamolybdenum Clusters Supported on Exfoliated h-BN Nanosheets for Photocatalytic Water Purification

Abstract

Nowadays, the development of new effective photocatalytic materials for the purification of real wastewaters and model systems containing organic molecules constitutes an important challenge. Here we present a preparation strategy for composite materials based on hexamolybdenum cluster complexes and exfoliated hexagonal boron nitride (h-BN) nanosheets. Cluster deposition on the nanosheet surface was achieved by impregnation of the matrix by a (Bu 4 N) 2 [{Mo 6 I 8 }(NO 3 ) 6 ]/acetone solution. Successful cluster immobilization and chemical composition of the samples were verified by inductively coupled plasma atomic emission spectroscopy, transmission electron microscopy with elemental mapping (TEM/EDS), X-ray photoelectron spectroscopy (XPS), and optical diffuse-reflectance spectroscopy. A small amount of water in acetone initiates the hydrolysis of a molybdenum cluster precursor with labile NO 3 − ligands, which are absent in the final composite, according to the XPS data. Intermediate hydrolyzed cluster forms anchor to the surface of h-BN nanosheets and promote growth of the insoluble compound [{Mo 6 I 8 }(H 2 O) 2 (OH) 4 ]•yH 2 O as the final hydrolysis product. TEM/EDS proves that the cluster exists at the nanosheet surface in the form of an X-ray diffraction amorphous thin film. The samples obtained show high photocatalytic activity in the degradation of a model pollutant rhodamine B under UV-and visible-light irradiation. The materials retain their initial photocatalytic efficacy during at least six cycles without the need for recovery.

Enhanced Photocatalytic Activity and Stability in Hydrogen Evolution of Mo6 Iodide Clusters Supported on Graphene Oxide

“…As molybdenum (and tungsten) is sufficiently cheap and abundant, their compounds constitute viable alternatives to costly noble metal-based luminophores, not to mention the environmentally hazardous lead-based hybrid perovskites and cadmium containing quantum dots [ 6 , 7 , 8 ]. Octahedral halide-bridged cluster compounds of Mo(II) and W(II), of the general type [M 6 X i 8 L a 6 ] (M = Mo, W; X i = Cl, Br, I (bridging or “inner”); L a = organic/inorganic ligand (terminal or “apical”, see Figure 1 ) show remarkable photoluminescence properties and emit red light in high quantum yields, which makes them particularly attractive in the design of functional hybrid nanomaterials [ 9 ] with potential applications in optoelectronic [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ], lighting [ 19 ], hydrogen storage [ 20 ], biomedicine [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ], catalysis [ 30 , 31 ], and photocatalysis [ 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ].…”

Zn–Al Layered Double Hydroxide Film Functionalized by a Luminescent Octahedral Molybdenum Cluster: Ultraviolet–Visible Photoconductivity Response

“…37,38 The photochemical and electrochemical properties of the MC come from the metal-metal and metal-ligand bonding, resulting in a strong absorption in both the UV-Vis lights and a prominent luminescent emission within the deep red/near-infrared (NIR) regions. The remarkable optical properties of the Mo6 MC are their i) high quantum yield, ii) large Stoke shift that avoids re-absorption losses, iii) strong luminescence, iv) phosphorescence in the infrared range, and v) UV-Vis absorption combined with an excellent photostability due to its through the recent developments of the optical-related inorganic devices, such as photocatalytic water purification, 39 nanoparticles for bioimaging, 40 photoelectrodes for solar cells 41 and photonic crystals. 34 The flexible interactions between the metal cluster core, apical ligand, and counter ion in the nanocomposite have become a challenge to figure out the right explanation for the optical property modification.…”

Zn-Al layered double hydroxide-based nanocomposite functionalized with an octahedral molybdenum cluster exhibiting prominent photoactive and oxidation properties

“…However, the Mo 6 cluster in the bulk powder state is limited in the applicability as well. Graphene oxide or h-BN are ones of the excellent candidates to enhance the photocatalytic applicability of the Mo 6 cluster has a proven highly catalytic efficiency for the hydrogen production from water [34], water purification [35], synthesis of dimethyl carbonate from CO 2 and methanol [36] or photoreduction of carbon dioxide into methanol [37]. A remarkable study has been progressing to simultaneously combine the gold nanoparticles and the Mo 6 cluster on the graphene oxide resulting in an excellent photoactive possibility for the degradation of rhodamine B under visible light irradiation [38].…”