Metallic salt precursor

Overview. Three approaches are used to make most sol—gel products method 1 involves gelation of a dispersion of colloidal particles method 2 employs hydrolysis and polycondensation of alkoxide or metal salts precursors followed by supercritical drying of gels and method 3 involves hydrolysis and polycondensation of alkoxide precursors followed by aging and drying under ambient atmospheres. 

In the case of MnO/ ( it is known to reduce on the surface of CNTs and graphene spontaneously to produce Mn02 NPs [182,183]. Solvothermal assisted precipitation of metal oxides can occur in milder solutions [184]. For example, mixed metal oxide NPs of CoFe204 have been deposited on GO from metallic salt precursors via the addition of ethanolamine followed by incubation at 180 °C in a sealed vessel [185]. Mixing GO with Cd2+ in DMSO followed by solvothermal treatment has been shown to both reduce GO to RGO and coat with CdS QDs [186]. 

Catalyst Metal Salt Precursor Molar ratio Mi Mo P Gas Flow / ml-min Reduction Temp. / K... 

Bimetallic DENs can be prepared using methodologies comparable to those for monometallic DENs. Important additional considerations are the interactions between metal salt precursors and the potential to control particle morphology... 

One approach for preparing carbon supported, non-noble metal core, Pt shell type particles is depicted in Fig. 9.11. First, a bulk alloy of Co(Ni)Au(Pd) is formed on the carbon support by reduction of the metal salt precursors. Surface segregation of the noble metal is achieved by hydrogen treatment at temperatures between 600 and 850°C. After this, a Cu monolayer is deposited at underpotential (Cu UPD) and displaced by Pt atoms. °... 

Only few works deal with films or nanoparticles covering the surface of a Nafion membrane. In the case of metal coated Nafion membranes surface nanoparticles were deposited on the surface by in situ reduction of a metal salt precursor [21], by adsorption of a colloidal dispersion of the metal [28], or by sputtering [22, 23]. 

Microwave-assisted methods have also been demonstrated by Tang and co-workers as an effective method to generate a versatile range of nanoarchitectures." Vertically aligned CNT-metal oxide hybrids, such as CNT/C03O4 shown in Fig. 13(a), have been reported whereby the CNT arrays are immersed in metal salt precursors and the metal oxide nanoparticles are formed after microwave irradiation for up to a minute. Particle ciystallinily and connectivity can be enhanced by an additional thermal annealing step. The potential for applications in supercapacitors... 

Cr, Mn, Co), from the nitridation of bimetallic oxide precursors with ammonia via TPR at the final reaction temperatures of 890-1110 K (70). The oxide precursors were prepared by conventional solid-state reactions. All the synthesized oxynitrides have face-centered cubic structures and large surface areas of 45-118 m /g. In addition, bimetallic and ternary-metallic oxynitrides were prepared by ammonolysis of metal salt precursors and NH3 gas in the various temperatures from 973 to 1023 K (71). 

Table 4 Metal salts precursors for electroless deposition and resulting metal morphology ...

Following the experimental procedure outlined for nonreactive surfactants, it was found that a range of R between 2 and 8, at fixed valnes of other microemulsion variables, snccessfully maintained stable colloidal particles of the different metal oxides. AtR<2, all the water was bounded to the snrfactant heads and no water was available to solubilize the metal salt precursor. For / > 8, on the other hand, cloudiness appeared indicating a shift towards Wmsor type n microemulsions. 

In addition, to facilitating the preparation of highly dispersed iron catalysts, the use of iron carbonyls and carbon supports facilitates the preparation of promoted catalysts to increase the selectivity to olefines. Thus, the use of mixed-metal carbonyl clusters as metal precursors allows the preparation of a variety of stoichiometric metal compositions, something difficult to reach by co-impregnation techniques. Furthermore, the mixed-metal carbonyl cluster should be activated by heating just to that minimum temperature which would decompose the cluster to yield reduced metal and CO, the temperature being <475 K. Hence, it is possible to obtain reduced metals under much less severe conditions than those used for conventional metal salt precursors. 

The ideal control on the structural and textural properties of perovskite-type oxides can be better achieved by exploiting aerosol spray synthesis methods to prepare highly dispersed and nanostructured materials from metal salt precursors. High-specific-surface-area (above 20m /g) crystalline perovskite-type oxides can be then obtained, which are suitable for a variety of applications. A major advantage of spray methods is that the material is directiy processed from the precursor solution with a reduced number of processing steps during powder synthesis (one-step approach), thus making them ideally suited for... 

There have been a number of synthetic protocols for the preparation of transition-metal nanoparticles, for example, vapor condensation, sonochemical reduction, chemical liquid deposition, reflux alcohol reduction, decomposition of organometallic precursors, hydrogen reduction, etc. Of these, the colloidal reduction route provides a powerful platform for the ready manipulation of particle structure and functionalization. One excellent example is the biphasic Brust method, in which nanoparticles are formed by chemical reduction of a metal salt precursor in the presence of stabilizing ligands. In a typical reaction, a calculated amount of a metal salt precursor is dissolved in water, and the metal ions are then transferred into the toluene phase by ion-pairing with a... 

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