Effect of organic stabilizers on Pt–Cu nanoparticle structure in liquid-phase syntheses: control of crystal growth and copper reoxidation

Abstract

The effect of organic stabilizers on the structure of supported Pt-Cu nanoparticles was investigated for liquid-phase reduction methods. The crystallite size and copper content of Pt-Cu alloy nanoparticles decreased as the number of carboxylate groups in an employed stabilizer molecule increased (acetate [ succinate [ citrate). The steric and inductive effects of carboxylate groups suppress the reduction and crystal growth of platinum to increase the chance for copper to make alloy with platinum, but at the same time they destabilize metallic copper resulting in a segregation of copper as oxides. In a radiolytic synthesis method, the size and Cu content in Pt-Cu nanoparticles were similarly reduced in the presence of citrate, but the copresent reduction enhancer also had a strong influence. The final particle structure was controlled by the kinetics of reduction of metal precursors and the thermodynamics of metal-stabilizer complexes.

Nano-amorphous calcium phosphate doped with citrate: Fabrication, structure, and evaluation of the biological performance

“…The stretching vibration of the PO 4 3À group shifted to higher wave number of 1075 cm À1 (S 0.025 , S 0.050 and S 0.100 ), which could be from the strong electron-withdrawing role of citrate. 27 Moreover, the non-split peaks illustrated the features of n-ACP, 28 and the characteristic absorption bands of S c were also observed. Therefore, the FT-IR analysis combined with the XRD results confirmed the structure of n-ACP with the citrate stabilizer.…”

High-Efficiency Biocidal Solution Based on Radiochemically Synthesized Cu-Au Alloy Nanoparticles

“…To prevent the oxidation of Cu-Au alloy NPs, ethylene glycol is added to scavenge the hydroxyl radicals (Scheme 1). According to Kugai et al [17], the radical ethylene glycol could reduce metal ions forming glycolaldehydes or glycolates (Scheme 2). The glycolate is a good stabilizer and can be chemisorbed on the metal surface to suppress crystal growth and promote copper alloying with gold [17].…”

“…According to Kugai et al [17], the radical ethylene glycol could reduce metal ions forming glycolaldehydes or glycolates (Scheme 2). The glycolate is a good stabilizer and can be chemisorbed on the metal surface to suppress crystal growth and promote copper alloying with gold [17]. During gamma irradiation, the solution of SDS and ethylene glycol, containing dissolved Au and Cu salts, in previously established concentration ratios, changes color from yellow-green to ruby-red, due to the formation of Cu and Au-based NPs (Figure 2).…”

“…As in the case of the synthesis of monometallic NPs, the morphology and crystal structure of metal alloy NPs can be controlled in particular by choosing appropriate methods of synthesis and control of some reaction parameters, such as the concentration of precursor ions and reducing agents, stabilizing agents, temperature, and time [6,7]. Thus, the metal alloy NPs can be obtained using both top-down and bottom-up approaches [8] by different methods, such as: chemical (e.g., chemical and electrochemical reduction [9], hydrothermal [10], precipitation [11], sol-gel [12], micro-emulsion [13]), physical (e.g., sputtering [14], thermal decomposition [15], microwaves [16], radiolytic [17], and sonochemical [18]) and biological (bacteria, fungi, plants, agricultural and industrial wastes) [19][20][21][22] procedures. Metal alloy NPs have an advantage over monometallic nanoparticle systems due to the synergism between the individual component alloy nanoparticle's characteristics and a more stable structure [8].…”

Nanoparticle Alloy Formation by Radiolysis

“…The authors claimed that the ethylene glycol protects the Cu metallic clusters and prevents them from the competing oxidation reaction. The effect of carboxylate containing compounds on platinum growth has also been studied …”