Platinum nanoparticles have been selectively deposited on composites of titanium oxide-carbon and tungsten oxide-carbon. Selectivity of the deposition made it possible to investigate changes in electronic properties of both platinum and oxide support, induced by the so-called strong metal–support interactions (SMSI). X-ray photoelectron spectroscopy (XPS) was used, and changes in binding energy of Pt 4f, Ti 2p, and W 4f core-levels and Pt 4f peak asymmetry were determined. These parameters allowed us to state the changes in local electron density, when Pt is deposited on oxide support. In all cases the binding energy of the Pt 4f signal for platinum deposited on an oxide support was significantly lower in comparison to samples where Pt was solely supported onto carbon. The increase in Pt 4f XPS signal asymmetry was observed. This suggests an increased electron density on Pt. No electron donor could be identified from the analysis of the oxide supports. To explain the observed data, at least two effects mu...

Metal–Support Interactions between Nanosized Pt and Metal Oxides (WO3 and TiO2) Studied Using X-ray Photoelectron Spectroscopy

A review of the analysis of multiple nucleation with diffusion controlled growth

Nucleation and diffusion-controlled growth of electroactive centers Reduction of protons during cobalt electrodeposition

Platinum dendrimer-encapsulated nanoparticles (DENs) were prepared within fourth-generation, hydroxyl-terminated, poly(amidoamine) dendrimers and immobilized on glassy carbon electrodes using an electrochemical coupling strategy. X-ray photoelectron spectroscopy, electron microscopy, and electrochemical experiments confirmed that the Pt DENs were about 1.4 nm in diameter and that they remained within the dendrimer following surface immobilization. The resulting Pt DEN films were electrocatalytically active for the oxygen reduction reaction. The films were also robust, surviving up to 50 consecutive cyclic voltammograms and sonication.

Electrocatalytic O2 reduction at glassy carbon electrodes modified with dendrimer-encapsulated Pt nanoparticles

Platinized Cu, Ni, and Co deposits have been formed on glassy carbon (GC) electrode substrates by a two-step process, whereby a controlled amount of the transition metal was electrodeposited onto GC and subsequently partially exchanged for Pt upon immersion of the Cu/GC, Ni/GC, and Co/GC electrodes into a chloroplatinic acid solution. The spontaneous partial replacement of the transition metal by Pt resulted in Pt(Cu)/GC, Pt(Ni)/GC, and Pt(Co)/GC electrodes whose composition and depth profile were obtained by energy-dispersive spectrometry (EDS) and sputter-etch Auger electron spectroscopy (AES). Following electrochemical conditioning (involving electrode exposure to the oxygen and hydrogen evolution potential regimes), all deposits displayed typical Pt surface electrochemistry in acid solutions. Pt(Cu) catalysts exhibited enhanced electrocatalytic activity for methanol oxidation both during voltammetric and constant potential experiments. The behavior of Pt(Ni) and Pt(Co) depended on the method of assess...

Vesselin Lazarov

Papers

Electrochemical nucleation and growth of rhodium on gold substrates

Electroless deposition of Pt on Ti. Part II. Catalytic activity for oxygen reduction

Electrocrystallisation of metal catalysts: nucleation and growth of platinum on a titanium electrode