Binary alloys, electrodeposited

The electrodeposition of alloys at potentials positive of the reversible potential of the less noble species has been observed in several binary alloy systems. This shift in the deposition potential of the less noble species has been attributed to the decrease in free energy accompanying the formation of solid solutions and/or intermetallic compounds [61, 62], Co-deposition of this type is often called underpotential alloy deposition to distinguish it from the classical phenomenon of underpotential deposition (UPD) of monolayers onto metal surfaces [63],... 

Electrodeposited binary alloys may or may not be the same in phase structure as those formed metallurgically. By way of illustration, we note that in the case of brass (Cu-Zn alloy), x-ray examination reveals that apart from the superstructure of... 

Electrodeposited binary alloys may or may not be the same in phase structure as those formed metallurgically. By way of illustration, we note that in the case of brass (Cu-Zn alloy), X-ray examination reveals that, apart from the superstructure of /3-brass, virtually, the same phases occur in the alloys deposited electrolytically as formed in the melt. Phase limits closely agree with those in the bulk. Debye-Scherrer interference rings indicate the presence of a strong distortion of the lattice, particularly in the a-phase brass. Electrodeposited a-brass, for instance, is... 

Srivastava RD, Mukerjee RC (1976) Electrodeposition of binary alloys an account of recent developments. J Appl Electrochem 6 321-331... 

The generalized thermodynamic condition for electrodeposition of A Bi binary alloy is defined as ... 

This is the general behavior that may be expected whenever there are two possible reactions in a given potential range. Most of the time in metal electrodeposition, these two reactions are the reduction of metal cations and the discharge of hydrogen ions, but other cathodic processes are also possible, e.g., the discharge of dissolved oxygen. A similar behavior is to be expected in the electrodeposition of binary alloys when the difference between the equilibrium potential of the two metal redox couples is remarkable. The typical shape of the polarization curve as briefly discussed... 

Yao K, Cheng YF (2007) Electrodeposited Ni-Pt binary alloys as electrocatalysts for oxidation of ammonia. J Power Sources 173 96-101... 

Bismuth-film electrodes (BiFEs), consisting of a thin bismuth-film deposited on a suitable substrate, have been shown to offer comparable performance to MFEs in ASY heavy metals determination [17]. The remarkable stripping performance of BiFE can be due to the binary and multi-component fusing alloys formation of bismuth with metals like lead and cadmium [18]. Besides the attractive characteristics of BiFE, the low toxicity of bismuth makes it an alternative material to mercury in terms of trace-metal determination. Various substrates for bismuth-film formation are reported. Bismuth film was prepared by electrodeposition onto the micro disc by applying an in situ electroplating procedure [19]. Bismuth deposition onto gold [20], carbon paste [21], or glassy carbon [22-24] electrodes have been reported to display an... 

Tellurium is a constituent common to several definite compounds having semiconducting properties which can be obtained by electrolytic deposition (e.g. CdTe, ZnTe,...). The low solubility of tellurium oxide in acidic aqueous solutions explains why its kinetics of electrodeposition, in the binary of tertiary alloys involved, is mainly controlled by mass transport. 

Since on pure platinum, methanol oxidation is strongly inhibited by poison formation, bimetallic catalysts such as PtRu or PtSn, which partially overcome this problem, have received renewed attention as interesting electrocatalysts for low-temperature fuel cell applications, and consequently much research into the structure, composition, and mechanism of their catalytic activity is now being undertaken at both a fundamental and applied level [62,77]. Presently, binary PtRu catalysts for methanol oxidation are researched in diverse forms PtRu alloys [55,63,95], Ru electrodeposits on Pt [96,97], PtRu codeposits [62,98], and Ru adsorbed on Pt [99]. The emphasis has recently been placed on producing high-activity surfaces made of platinum/ruthenium composites as a catalyst for methanol oxidation [100]. 

The model based on metal-hydroxide ions ([MOH]+) was further developed by Grande and Talbot [71]. Sasaki and Talbot [72] demonstrated the extendibility of this model to the electrodeposition of Co—Fe and Ni—Co alloys. They found that there is a slight inhibition of the more positive metal deposition and a promotion (acceleration) of the less positive metal deposition for all binary iron-group alloys. 

Ga(III) leads first to Ga(I), then upon further reduction the elemental Ga forms from Ga(I). On glassy carbon the electrodeposition involves instantaneous three-dimensional nucleation with diffusion-controlled growth of the nuclei. No alloying with A1 was reported if deposition of Ga was performed in the Ga(I) diffusion regime. Reproducible electrodeposition of Ga is a promising route to binary and ternary compound semiconductors. A controlled electrodeposition of GaX quantum dots (X = P, As, Sb) would be very attractive for nanotechnology. 

Pt-Ru electrocatalysts are generally considered to be the most active binary catalysts for the MOR. Several commercial Pt-Ru alloy nanoparticles supported on carbon black have been available for applications in DAFCs. The catalytic effect has been observed using different kinds of Pt-Ru materials, such as adsorbed Ru on bulk Pt [46, 47], UHV-evaporated Ru on bulk Pt [46, 47], Pt-Ru electrodeposits [48, 49], Pt-Ru alloys [50-60], and Pt-RuOj [63-66]. 

Without the colloid present (i.e., electrodeposition from pure aqueous media), a Pt-rich catalyst was formed, typically only on the outer surface of the three-dimensional support, without significant penetration into the matrix. For codeposition throughout the thickness of the support of binary and ternary catalyst formulations, with atomic compositions relevant to fuel cell application, the presence of the colloidal system was essential. The mechanism of action for the surfactant or water-in-oil microemulsion is believed to be related to selective blocking of the surface, creating a high-Pt electrocrystallization overpotential, thereby lowering the Pt electrodeposition rate relative to the alloying elements (e.g., Ru, Mo, or Sn). 

In the following, we discuss the PtRu system as a model catalyst. Binary PtRu electrocatalysts are presently studied in many different forms, PtRu alloys [65-68], Ru electrodeposits on Pt [69, 70], PtRu... 

Sulfite electrolytes for colored gold alloys are also in use for decorative deposition thanks to their excellent distribntion and leveling properties and also for their superior ductility compared to gold alloy deposits from acid cyanide electrolytes giving similar shades and colors [90], Alloy plating from snlflte electrolytes comprises binary and ternary compositions, such as Au-Cu, Au-Pd, and An-Cn-Pd—already reported by Rapson [3] and later incorporated into proprietary processes [91-93], The later is an alloy finish widely used in the electroplating of spectacle frames. Example formnlations of nentral and alkaline sulflte baths for the electrodeposition of gold alloy deposits are reported in Table 11.8. 

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