A nanocomposite superstructure of metal oxides with effective charge transfer interfaces

Abstract

The alignment of nanoparticle building blocks into ordered superstructures is one of the key topics in modern colloid and material chemistry. Metal oxide mesocrystals are superstructures of assembled nanoparticles of metal oxides and have potentially tunable electronic, optical and magnetic properties, which would be useful for applications ranging from catalysis to optoelectronics. Here we report a facile and general approach for synthesizing metal oxide mesocrystals and developing them into new nanocomposite materials containing two different metals. The surface and internal structures of the mesocrystals were fully characterized by electron microscopy techniques. Single-particle confocal fluorescence spectroscopy, electron paramagnetic resonance spectroscopy and time-resolved diffuse reflectance spectroscopy measurements revealed that efficient charge transfer occurred between n-type and p-type semiconductor nanoparticles in the composite mesocrystals. This behaviour is desirable for their applications ranging from catalysis, optoelectronics and sensing, to energy storage and conversion.

Formation of ZnO/Ni_0.6Zn_0.4O Mixture Using Mechanical Milling of Zn-NiO

“…This is an indication of substitution of Ni (ionic radius: 0.69 Å) with Zn (ionic radius: 0.74 Å) 3) and formation of the SEM morphology of the 72000 seconds (20 hrs) as-milled sample and the isothermally-heated (Argon ow) 1800 seconds milled Zn-NiO mixtures are depicted in Fig. 5(a) and 5(b), (c) respectively.…”

“…The coordination environment of the Zn 2+ sites in ZnO is suitable for nickel ions (Ni 2+ ) and this is the reason why NiO and ZnO form a solid solution. [1][2][3] The resulting complex structure depends on the x value. To the best of our knowledge, work on the solid state synthesis of such structures is quite limited.…”

Facile synthesis of SiO2@TiO2 crystallite photocatalysts with enhanced interaction level and high light absorption efficiency

“…In general condition, anatase TiO 2 crystallite grows with the preferential exposure of {101} facet with a lower surface energy, which leads to the formation of tetragonal bipyramidal TiO 2 nanocrystals. It was reported that fluorine-containing species can favor the preferential exposure of {001} facet of anatase and thus the formation of TiO 2 nanoplate [6,12,21]. TS20 and TS40 without regular TiO 2 crystal shape show mullein-like morphology as shown in clearly shows an amorphous covering on an exposed crystallographic plane of TiO 2 crystallite, which confirms the formation of core-shell microstructure.…”

“…Moreover, TiO 2 absorbs UV light that is the tiny portion of solar spectrum but has meager response to visible light due to a wide band gap of TiO 2 [6,7]. Fortunately, many novel approaches like doping with impurities [8][9][10], noble metal deposition [11,12], sensitizing with narrow band gap absorption materials [13,14] and hydrogenation process [15,16] have been found to be effective in enabling visible light absorption, while several inventive techniques such as heterostructuring with other semiconductors [17,18], integrating with carbon nanostructures [19,20], designing with exposed reactive facets [12,21] and hierarchical morphologies [22,23] have been developed to improve structural stability and charge carrier separation kinetics.…”

TiO2 mesocrystal with nitrogen and fluorine codoping during topochemical transformation: Efficient visible light induced photocatalyst with the codopants

“…The samples were synthesized with some modifications according to the previous reports [22][23][24]. A precursor solution containing TiF 4 , H 2 O, NH 4 NO 3 , and NH 4 F (molar ratio = 1:503.4:4.9:2.4) was prepared, and were placed on a silicon wafer to form a thin layer.…”