Polyoxometalate-stabilized Pt nanoparticles and their electrocatalytic activities

Abstract

The synthesis of long-term stable polyoxometalate (POM)-stabilized Pt nanoparticles (NPs) is described here. By means of controlled bulk electrolysis, the reduced POM anions, SiW(12)O(40)(4-) (or SiW(12)) and H(2)W(12)O(40)(6-) (or H(2)W(12)), respectively, served the dual role of reductant and protecting/stabilizing ligand for the Pt NPs. Transmission electron microscopy (TEM) images confirmed the formation of 3 to 4 nm sized Pt NPs, which coincidently was in the same size range of the commercial Pt black that was used as a reference. Elemental XPS analyses showed W/Pt ratios of 0.12 for the SiW(12)- and 0.18 for the H(2)W(12)-stabilized Pt NPs, but found no evidence of the presence of Cl(-) anion in the samples. Controlled electrochemical (EC), UV-Vis, and IR data provided unambiguous evidence for the structural integrity of the POM anions on the Pt NP surface. CO stripping, methanol oxidation reaction (MOR), and oxygen reduction reaction (ORR) were used to assess their electrocatalytic activities. It was found that both SiW(12)- and H(2)W(12)-stabilized Pt NPs showed enhanced activities in MOR and ORR as compared to that of Pt black, with the latter having higher enhancement. These observations clearly demonstrated that the stabilizing POM anions have a profound influence on the electrocatalytic activity of the underlying Pt NPs.

Investigation of a Silicotungstic Acid Functionalized Carbon on Pt Activity and Durability for the Oxygen Reduction Reaction

“…Thus, we would expect the stability provided by HPA that has been observed by others 17,20,24,32 to also aid in the uniform spatial distribution of Pt in this case, due to the support functionalization. This can be seen to some extent in the lower magnification TEM images (Supporting Figure 3, 31 ), but the argument is fairly subjective.…”

Highly selective detection of cellular guanine and xanthine by polyoxometalate modified 3D graphene foam

“…It has been confirmed that the introduction of POM into hybrid structures was beneficial to proton conduction and electrocatalytic activity [66][67][68]. Previous studies also illustrated that there were strong hydrogen bonding or ionic interaction between POMs and graphene, making it promising for selective detection of biomolecules or even in accurate evaluation for metabolic levels of intracellular biomolecules [69,70]. Herein, by using classical Keggin type polyoxometalate of dodecamolybdophosphate acid and 3DGF, an ultrastable and highly selective GCE modified with POM@3DGF hybrid was successfully fabricated and used as new type biosensor to detect cellular Xan and Gua simultaneously for the first time.…”

Phosphomolybdate@Carbon‐Based Nanocomposites as Electrocatalysts for Oxygen Reduction Reaction

“…[6,7] Mbomekalle and co-workers published several works reporting the application of several pristine POMs (Cu(II)- [25] and Mn(II)- [26] substituted polyoxoanions) as ORR electrocatalysts and promising results were obtained, with significant positive shifts in potentials of oxygen reduction, that occurs in the potential range E =-0.5 to 0.0 V (vs. Ag/AgCl) accordingly with the POM employed. As cocatalysts, the combination of POMs with a porphyrin [6] and Au, [7] Pd [27] and Pt [28,29] nanoparticles (NPs) was also described, resulting in enhanced ORR performances with a significant positive shift of the ORR potential for E = 0.5 -0.7 V (vs. Ag/ AgCl).…”