Delafossite oxides

Delafossite CuCr02 has attracted considerable attention as a p-type transparent conductive oxide (TCO), and is appealing for use in several applications, such as transparent diodes and solar cells [1-3], Relevant studies on delafossite oxides have not only examined the properties of TCOs, but have also explored the application of delafossite oxides as photocatalysts for hydrogen evolution [4] and NO2 removal [5], catalysts for steam reforming processes [6] and exhaust gas purification [7], room temperature ozone sensors [8], magnetics [9], and thermoelectric devices [10]. 

The interest in the synthesis and properties of delafossite structured compounds that have the general formula of ABO2 have grown due to their p-type conductivity and optical transparency. The application of ultrasound for the synthesis of ternary oxide AgMC>2 (M = Fe, Ga) has been investigated by Nagarajan and Tomar [44]. Above materials were obtained in crystalline form within 40-60 min of sonication. 

Sheets, W.C., Mugnier, E., Barnabe, A., Marks, T.J. and Poeppelmeier, K.R. (2006) Hydrothermal synthesis of delafossite-type oxides. Chemistry of Materials, 18, 7-20. 

Relatively few ternary palladium oxides have been reported in the literature. Various alkali metal-palladium oxides are known (14,15,16). Intermediate compounds have been found in several Ln203-Pd0 systems with Ln = La, Nd, Sm, Eu, Gd, and Dy (3). At high pressures, pyrochlores of the type Ln2Pd207 can be prepared (19). Recently, the delafossite-like compounds PdCo02, PdCr02, and PdRhOo have been studied (18). 

On the basis of both interatomic distances and physical properties it would seem justifiable to subdivide the compounds with structure (b) of Table 6.7 (Fig. 6.22(d)) into two classes. There are numerous oxides with this structure, sometimes called the delafossite structure after the mineral CuFe02 ... 

Azides also present interesting analogies to other compounds with linear groups, and we have pointed out the structural similarities of some azides with oxides with O-Cu-O groups (delafossites) and with linear F-H-F groups. 

The latest systems appear to work under visible light illumination without a noble metal-based H2 and/or O2 catalyst There have been reported photocatalysts such as delafossite CuFe02, without a separate H2 or O2 catalyst, or In/NiAra-oxides coated with NiO, or RUO2 for visible-light activated water-splitting processes. However, all reported water-splitting systems are controversial and require confirmation [3]. 

In their ab initio study on CUMO2 (M=A1, Ga, Y) delafossite-type oxides Buljan et a/. analysed the bonding in the Cu layers. The topological analysis revealed the existence of weak attractive d -d interactions that were suggested... 

In 2012, Burlet et al. showed that strong spectroscopic evidence proved that the mineral structure could be better described by the chemical formula HC0O2 instead of CoO.OH [5]. The mineral should be thus considered as a cobaltic acid [12] instead of a cobalt oxy-hydroxide [3]. Heterogenite was in consequence categorized as a layered oxide with a delafossite-type structure [5]. 

Delafossite Type Oxide, Method for Manufacturing the Exhaust Gas Purification Catalyst, Japanese Patent No.2008-156130. 

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