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Mixed oxide
About: Mixed oxide is a research topic. Over the lifetime, 5224 publications have been published within this topic receiving 115567 citations.
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TL;DR: In this article, a combination of effective charge carrier separation and improved electron transfer in highly crystalline barium tantalate composites modified with Rh-Cr2O3 core-shell co-catalyst systems induces enhanced activity for overall water splitting (OWS) with stoichiometric amounts of H2 and O2.
Abstract: The combination of effective charge carrier separation and improved electron transfer in highly crystalline barium tantalate composites modified with Rh–Cr2O3 core–shell co-catalyst systems induces enhanced activity for overall water splitting (OWS) with stoichiometric amounts of H2 and O2 (2 : 1). A sol–gel route employing complexing reagents was investigated to prepare selectively defined mixed oxide materials with improved surface areas and smaller particle sizes compared to the conventional solid state reaction (SSR). The catalytic activities of the materials are investigated in photocatalytic test reactions for hydrogen production and overall water splitting. The formation of Rh–Cr2O3 core–shell co-catalyst systems for water splitting is evidenced by transmission electron microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). Moreover, we developed new and highly active barium tantalate composites for hydrogen generation from aqueous methanol solutions under UV-light, which show the highest hydrogen evolution rate for a three-component composite consisting of Ba5Ta4O15/Ba3Ta5O15/BaTa2O6. Hydrogen rates of more than 6 mmol h−1 can be achieved without any co-catalyst. Using Rh–Cr2O3 core–shell co-catalysts on these three-component composites simultaneous generation of H2 and O2 from pure water splitting reaches rates up to 70% higher than for the pure Ba5Ta4O15.
47 citations
TL;DR: In this paper, thin films of uranium cerium mixed oxides have been prepared by DC sputtering and characterized by X-ray photoelectron spectroscopy (XPS) for reduction and oxidation properties.
47 citations
TL;DR: In this paper, a spinel-structured, mixed oxide called CoxCryO4 was prepared by electro-deoxidation in molten calcium chloride at 1123 K. Constant voltage chronoamperometry was used both to prepare the alloy and to investigate its mechanism of formation.
47 citations
TL;DR: A series of titania and silica mixed metal oxide samples modified by H2SO4 has been characterized by BET, XRD, XPS, FT-IR and compared with non sulfated samples as discussed by the authors.
Abstract: A series of titania and silica mixed metal oxide samples modified by H2SO4 has been characterized by BET, XRD, XPS, FT-IR and compared with non sulfated samples. The XPS results show the appearance of a titanium silicate phase in all samples. After sulfuric acid treatment the decrease of BET surface area, the appearance of the TiO2 crystalline in XRD and the enrichment of Si on the surface in XPS indicate that the strong bond between TiO2 and sulfate ions induces the migration of Ti ions from the titanium silicate phase. The total contents of sulfate ions depend on the TiO2-SiO2 mole ratio. The shift of the S=O characteristic peak in FT-IR shows that the bond strength of S=O is influenced by the TiO2-SiO2 microstructure. (C) 2001 Elsevier Science B.V. All rights reserved.
47 citations
TL;DR: The high activity and low cost of the Co-Mn mixed-oxide catalysts prepared by solid-state grinding make it promising for industrial application for the manufacturing of polyethylene furanoate, a bioreplacement for polyethylenes terephthalate, from sustainable bioresources.
Abstract: A highly active and inexpensive Co-Mn mixed-oxide catalyst was prepared and used for selective oxidation of 5-hydroxymethylfurfural (HMF) into 2, 5-furandicarboxylic acid (FDCA). Co-Mn mixed-oxide catalysts with different Co/Mn molar ratios were prepared through a simple solid-state grinding method-a low-cost and green catalyst preparation method. The activity of these catalysts was evaluated for selective aerobic oxidation of HMF into FDCA in water. Excellent HMF conversion (99 %) and FDCA yield (95 % ) were obtained under the best reaction conditions (i.e., 120 °C, 5 h, Co-Mn mixed-oxide catalyst with a Co/Mn molar ratio of 0.25 calcined at 300 °C (Co-Mn-0.25) and 1 MPa O2 ). The catalyst could be reused five times without a significant decrease in activity. The results demonstrated that the catalytic activity and selectivity of the Co-Mn mixed-oxide catalysts prepared through solid-state grinding were superior to the same Co-Mn catalyst prepared through a conventional coprecipitation method. The high catalytic activity of the Co-Mn-0.25 catalyst was attributed to its high lattice oxygen mobility and the presence of different valence states of manganese. The high activity and low cost of the Co-Mn mixed-oxide catalysts prepared by solid-state grinding make it promising for industrial application for the manufacturing of polyethylene furanoate, a bioreplacement for polyethylene terephthalate, from sustainable bioresources.
47 citations