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Homogeneous platinum alloy nanoparticles (NPs) are of great interest to the electrocatalytic community for potential use in various fuel cell electrodes. Increasing the surface area available per unit mass by decreasing the size of NPs while maintaining or improving activity is one of the key tasks of fuel cell catalysis. Achieving both in a synthesis of multielement NPs is still a challenging workup. In this investigation, we report the use of glycine as a size control agent to make ultrasmall homogeneous trimetallic PtNiCu NPs within 2-5 nm range. The mechanistic roles of dimethyl formamide (DMF), formaldehyde, water, and glycine are explored to understand the formation of these small NPs. Interestingly, it was observed that these PtNiCu NPs exhibited substantially enhanced mass activities toward the electro-oxidation of ethanol in comparison to commercial Pt black.

Nearly monodispersed spherical silver nanoparticles (Ag NPs) were synthesized by using tannic acid (TA) as both reductant and stabilizer in a 30 °C water bath. The size of the as-prepared Ag NPs could be tuned in a range of 7-66 nm by changing the molar ratio of TA to silver nitrate and pH of the reaction solutions. UV-vis spectra, TEM observations, and temporal evolution of the monomer concentrations for the reactions carried out at different experimental conditions showed that the improved size distribution and size tunability of the Ag NPs were mainly attributed to the use of TA, which could promote the balance of nucleation and growth processes of the NPs effectively. The size of the Ag NPs was extendable up to 200 nm in one-pot fashion by the multi-injection approach. The size-dependent surface-enhanced Raman scattering (SERS) activity of the as-prepared Ag NPs was evaluated, and the NPs with size around 100 nm were identified to show a maximum enhanced factor of 3.6 × 10(5). Moreover, the as-prepared TA-coated Ag NPs presented excellent colloidal stability compared to the conventional citrate-coated ones.