First row transition metal oxides

Preparation and properties of high valent first row transition metal oxides and halides. C. Rosen-blum and S. L. Holt, Transition Met. Chem. (N.Y.), 1972, 7,87-182 (303). 

It should be mentioned that, of the other first-row transition metal oxides crystallizing with the NaCl structure, none has been found to superconduct down to 2.5 K. Some of these oxides undergo magnetic ordering at low temperature and most behave as semiconductors at all temperatures. These would include MnO, FeO, CoO, and NiO. Studies performed on CuO, which has a different crystalline structure, showed only semiconducting behavior to very low temperatures (1.9 K). 

A review of recent research, as well as new results, are presented on transition metal oxide clusters, surfaces, and crystals. Quantum-chemical calculations of clusters of first row transition metal oxides have been made to evaluate the accuracy of ab initio and density functional calculations. Adsorbates on metal oxide surfaces have been studied with both ab initio and semi-empirical methods, and results are presented for the bonding and electronic interactions of large organic adsorbates, e.g. aromatic molecules, on Ti02 and ZnO. Defects and intercalation, notably of H, Li, and Na in TiC>2 have been investigated theoretically. Comparisons with experiments are made throughout to validate the calculations. Finally, the role of quantum-chemical calculations in the study of metal oxide based photoelectrochemical devices, such as dye-sensitized solar cells and electrochromic displays, is discussed. 

The first row transition metal oxides are also surprisingly volatile (Figure 6). Iron (primarily relying on estimates based on the relatively limited data for halides), appears to possess the most stable oxide with acceptable volatility to temperatures as high as 1000°C. Ruthenium and copper oxides are extremely volatile and caimot be tecoimnended as active components in combustion catalysts. The least volatile transition metal oxide is iron (based primarily on estimated enthalpies of formation). A trend is observed for the more active transition metal oxides of increasing volatil-... 

Andreev, A. Idakiev, V. Mihajlova, D. Shopov, D. Iron-based catalysts for the water-gas shift reaction promoted by first-row transition metal oxides. Appl. Catal. 1986, 22 (2), 385-387. 

Band Theory A Case Study of the First-row Transition Metal Oxides... 

ToF-SlMS is mainly referenced in the characterization of polymers and organic additives and blends [19-26] only few investigations of catalysts are reported in the litterature [27-29]. However, inorganic applications of ToF-SIMS were illustrated by Aubriet et al. [30] who studied the behaviour of the first row transition metal oxides and proposed, for each of them, a reliable methodology of speciation. 

Fig. 15. Activities of first-row transition-metal oxide perovskites for CO oxidation in a 2 1 mixture of CO and 02 at atmospheric pressure (a) or in a 1 1 mixture of CO and 02 at 227°C at atmospheric pressure (b). The activities of vanadates ( ), chromates ( ), manga-nates (A), ferrates (O), cobaltates ( ), and nickelates ( ) are plotted at the appropriate d-orbital occupation corresponding to the average valence of the transition-metal ion. (Redrawn by permission from Refs. 14 and 176.)...

A number of recent calculations have compared the classical result with quantum mechanical calculations. In many cases, the results from the latter techniques confirm those from classical calculations with a gratifying accuracy. However, one topic on which there is continuing controversy is the nature of the polarons in transition metal oxides. Since the classical method subsumes all the quantum mechanics of the problem into the potential function, it can only tackle problems of electronic structure in a few specific cases, the most common example of which is in non-stoichiometric oxides. Here the question is the location of the electronic hole when the system is metal deficient. The only way such a problem can be tackled by classical methods is to use the small polaron approximation and assume that the hole resides on an ion to produce a new (in effect substitutional) ion with an extra positive charge. This can be successful and the use of the small polaron approximation in crystals is discussed in detail by Shluger and Stoneham (1993). However, all calculations on the first-row transition metal oxides have assumed that the extra charge resides on the metal ion. Recent quantum calculations (Towler et al., 1994) have thrown doubt on this assumption, suggesting that the hole is on the oxide ion. Moreover, the question of whether the hole is a small polaron for all these oxides is, at present, quite uncertain. Further discussion is given in Chapter 8. 

Synthesize mixed metal oxides consisting of CuO/Cu20 and another first-row transition metal oxide based on thermodynamic calculations. 

Mixed metal oxides consisting of a combination of Cu and another first-row transition metal oxide, such as Co, Mn, and Ni, were synthesized by various techniques, including coprecipitation and glycine-nitrate combustion. Some of the mixed metal oxides were dispersed on a high-surface-area 6-alumina. The H2S uptake of the candidate metal oxides was evaluated using a microreactor system with an online gas chromatograph equipped with a flame... 

Fig. 1. Activity patterns of first row transition metal oxides at 300° C for (1) homo-molecular exchange of oxygen, (2) oxidation of hydrogen, (3) oxidation of methane and (4) nitrogen oxide decomposition. Adapted from reference [10] with permission.

Fig. 6. Relationship between Tamman temperature and the rate of R1 + R2 exchange for some first row transition metal oxides. Reproduced from reference [17] with permission.

Ponec and co-workersl l have recently demonstrated a relationship between the Tamman temperature and the Ri and R2 exchange rate for some first row transition metal oxides as shown in Fig. 6. In this study, the Tamman temperature plotted is the ratio of the exchange reaction temperature to the Tamman temperature of the oxide. This was taken to be indicative of the importance of diffusion, with surface diffusion occurring in the 0.2-0.5 temperature range and a bulk diffusion beyond 0.5. 

This chapter presents a critical review on the newly developed procedures for multidimensional electrode nanoarchitecturing for Li- and Na-ion batteries. Starting from nt-Ti02 utilization, first-row transition metal oxide nanocomposites are examined. Metal foams for 2D and 3D battery architectures and graphene-transition metal oxide heterostructures with unusual performance for battery applications are discussed. 

First-Row Transition Metal Oxide Nanocomposites with Unusual Performance... 

After the success of the Li-Ion battery, the research for cathode-active materials has been concentrating on Uthinm-containing first-row transition-metals oxide with 4 V-class high electromotive force, because it can serve as a Uthium source to a carbon-negative electrode. Unfortunately, all 4 V-cIass rechargeable cathodes, LiCoO, LiNiOj, and LiMn O, have the essential problans of cost and environmental impact, because these cathodes commonly include rare metals as redox center. As shown in Table 9.1, these problems become serious especially for LiCoO along with the further rapid growth of the market for electric vehicles expected in the near future. 

Biesinger MC, Payne BP, Grosvenor AP, Lau LW M, Gerson AR, Smart RSC (2011) Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides Cr, Mn, Fe, Co and Ni. Appl Surf Sci 257 (7) 2717-2730... 

The spinel structure, named from the mineral spinel, MgAl204, is very common for many of the first row transition metal oxides. It has an O/M ratio of 1.33, and numerous transition metal oxides adopt this structure when they have this M/0 ratio. In fact, the structure is so stable that even stoichiometries substantially differ-... 

A FIGURE 24.4 First-Row Transition Metal Oxidation States The transition metals exhibit many more oxidation states than the main-group elements. These oxidation states range from -1-7 to -H. 

Layered materials possess a two-dimensional structure that provides the path for intercalation/de-intercalation of lithium ions along the interlayer planes. First-row transition-metal oxides and chalcogenides used to be considered as seminal hosts for reversible intercalation/de-intercalation of lithium ions. But it is also desirable that the two-dimensional material possess a high Li insertion/de-insertion range (Ax). Usually achieving Ax value of 1/transition metal ion is considered as the maximum limit since it involves the change of the oxidation state of all metal ions by 1-unit. 

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