Citrate-Coated, Size-Tunable Octahedral Platinum Nanocrystals: A Novel Route for Advanced Electrocatalysts

Abstract

The development of green and scalable syntheses for the preparation of size-and shape-controlled metal nanocrystals is of high interest in many areas, including catalysis, electrocatalysis, nanomedicine, and electronics. In this work, a new synthetic approach based on the synergistic action of physical parameters and reagents produces size-tunable octahedral Pt nanocrystals, without the use of catalyst-poisoning reagents and/or difficult-to-remove coatings. The synthesis requires sodium citrate, ascorbic acid, and fine control of the reduction rate in aqueous environment. Pt octahedral nanocrystals with particle size as low as 7 nm and highly developed {111} facets have been achieved, as demonstrated by transmission electron microscopy, X-ray diffraction, and electrochemical methods. The absence of sticky molecules together with the high quality of the surface renders these nanocrystals ideal candidates in electrocatalysis. Notably, 7 nm bismuth-decorated octahedral nanocrystals exhibit superior performance for the electro-oxidation of formic acid in terms of both specific and mass activities.

Dispersion state phase diagram of citrate-coated metallic nanoparticles in saline solutions

“…etal nanoparticles (NPs) with different composition, morphology, and surface chemistry can be used for applications like NP-mediated catalysis [1][2][3][4] , cancer therapy [5][6][7] , and chemosensing [8][9][10][11] . To ensure the solubility of pristine metallic NPs in polar solvents, stabilizing agents like citrate and tetraoctylammonium bromide must be introduced into the mixture.…”

Atomic Carbon Layers Supported Pt Nanoparticles for Minimized CO Poisoning and Maximized Methanol Oxidation

“…Besides their high prices, Pt-based catalysts are susceptible to carbonaceous intermediates, especially CO. For example, the CO adsorption on the Pt surface is especially serious in acidic electrolytes, leading to severe poisoning effect or short life time of these catalysts towards MOR. [4][5][6][7] Design and synthesis of high-performance Pt electrocatalyst for MOR (namely maximized catalytic ability towards MOR but minimized CO poisoning effect during MOR) is thus highly demanded.For such a demand, numerous Pt nanostructures (e.g., hollow nanospheres, [8] nanorods or wires, [9,10] nanoclusters, [11] nanoflowers, [12] octahedral, [13,14] nanosponges, and etc. [15] ) have been synthesized using various approaches.…”

“…For such a demand, numerous Pt nanostructures (e.g., hollow nanospheres, [8] nanorods or wires, [9,10] nanoclusters, [11] nanoflowers, [12] octahedral, [13,14] nanosponges, and etc. [15] ) have been synthesized using various approaches.…”

Intracellular Antioxidant Activity of Biocompatible Citrate-Capped Palladium Nanozymes

“…TEM micrographs mostly show small particle aggregates dispersed into endo/lysosomes, with some single NPs also present (especially for Pd4). Interestingly, analyzing the size of the internalized particles, we observed that PdNPs typically maintain their pristine size after 24 h. This suggests that the particles do not undergo significant dissolution when exposed to the acidic and degradative environment of lysosomes, unlike for instance silver NPs [40,57]. In light of these results, the biocompatibility of PdNPs could be ascribed to the stability of the material (i.e., resistance to the acidic corrosion) in the cellular environment and absence of significant Pd ion release.…”

“…The application of nanomaterials in nanomedicine and nanodiagnostics requires a strict control of their physico-chemical properties, achievable by a careful design of the synthetic procedure [5,7,28,[31][32][33][34][35][36][37][38][39][40]. To this purpose, we developed a new protocol for the synthesis of PdNPs that provides low polydispersity along with size tunability, combined with reagents known to be biocompatible, green, or easy to remove after synthesis.…”