Density functional theory study of platinum oxides: From infinite crystals to nanoscopic particles

Abstract

For over a century, platinum oxides find technologically relevant applications in various fields ranging from catalysis to electrochemistry and nanoelectronics. We have performed a density functional theory study of the PtO, Pt3O4, and PtO2 bulk oxide phases. In our calculations, PtO and Pt3O4 present metallic character at the simple generalized gradient approximation level. The application of Hubbard corrections to the Kohn-Sham Hamiltonian opens a small gap in the electronic band structure of PtO, but not of Pt3O4, in which metallic Pt-Pt bonds are revealed by a Bader analysis of the calculated electronic structure. These results, together with the noninteger oxidation number of the Pt ions, are indicative of metallicity of the Pt3O4 phase which may be consistent with the known metallic character of platinum bronzes. Moreover, we have calculated the relative thermodynamic stabilities of platinum oxide Wulff's particles and discussed the results in the context of catalysis. Finally, we have predicted that the formation of alpha-PtO2 nanotubes could be energetically feasible. This result is of potential interest both for nanotechnological and catalytic applications and may explain the formation of curled alpha-PtO2 sheets observed in high-resolution transmission electron microscopy images

In Situ Oxidation Study of Pt Nanoparticles on MgO(001)

“…Our results clearly show that the majority of bulk oxides formed on sample II displayed the structure of (110)-oriented Pt 3 O 4 which disagrees with DFT studies according to which α-PtO 2 bulk oxides are regarded to be thermodynamically more stable, especially for smaller particles 82 . Our findings partially agree with a recent XPS study on oxidized Pt nanoparticles in which α-PtO 2 and PtO were assigned to be the formed bulk oxides 54 .…”

Low‐Dimensional, Hinged Bar‐code Metal Oxide Layers and Free‐Standing, Ordered Organic Nanostructures from Turbostratic Vanadium Oxide

“…Concurrent curvature of the metal oxide on the molecular level has shown to be theoretically possible. [51] An increase in the interlaminar distance only occurs when tightly (chemically) bound water is removed during HT, due to the well documented condensation mechanism. [52] The cleavage of the lamina could also be attributed to the sheer stress induced by the loss of coordinated water during HT recrystallization from monoclinic to the more distorted orthorhombic V 2 O 5 [36] , which can accommodate structural distortion and bending.…”

Study of the Histamine Electrochemical Oxidation Catalyzed by Nickel Sulfate

“…Because the electrochemical response is strongly conditioned by the burning ( [26][27]) we choose to burn the electrode, during fifteen minutes after the blue flame appears. Indeed, several types of oxides can appears such PtO, Pt 3 O 4 , PtO 2 [28][29][30] and reactivity of the electrode, (platinum successive oxidations, catalytic ability) can change.…”

“…Curve 1 is the residual current, obtained from a solution of KCl (0.2 M) at pH 12.6 without histamine nor nickel; it shows a nicely resolute peak starting around 0.55 V for which the max current was located at~0.82 V, attributed to the platinum/platinum oxide electrode to higher platinum valences (Pt x O y ) [28][29][30].…”

“…0.6 V for which the maximum current was located at 0.75 V, followed by a shoulder (0.8-1 V). Signals were attributed respectively to the oxidation of Ni (II) to Ni (III) and to the platinum/platinum oxide electrode to higher platinum valences (Pt x O y ) [28][29][30].…”