Recent Research Highlights

The design of an active site towards optimal electrocatalysis: Overlayers, surface alloys and near-surface alloys of Cu/Pt(111)     Aliaksandr S. Bandarenka, Ana Sofia Varela, et al.   Published in Angewandte Chemie (2012)      Hydrogen Production from a Molybdenum Sulfide Catalyst on Ti-protected n+p -Silicon Photocathode     Brian Seger, Anders B. Laursen, et al.   Published in Angewandte Chemie International (2012)          Pt5Gd as a highly active and stable catalyst for oxygen electroreduction     Read more     Hydrogen Production Using a Molybdenum Sulfide Catalyst on a Titanium-Protected n+p-Silicon Photocathode     A low-cost substitute: A titanium protection layer on silicon made it possible to use silicon under highly oxidizing conditions without oxidation of the silicon. Molybdenum sulfide was electrodeposited on the Ti-protected n+p-silicon electrode. This electrode was applied as a photocathode for water splitting and showed a greatly enhanced efficiency. Read more.     Cathrine Frandsen – Science Publication: "Electron Small Polarons and Their Mobility in Iron (Oxyhydr)oxide Nanoparticles"     Together with American collaborators, associate professor Cathrine Frandsen from DTU Physics and CINF has just published a study on the kinetics of electron mobility, in rusty nanoparticles! Read more.     The effect of size on the oxygen electroreduction activity of mass-selected platinum nanoparticles In this paper, we demonstrate that the specific activity of the oxygen reduction reaction on Pt nanoparticles decreases with particle size, with a maximum in mass activity for 3 nm particles. The ORR activity roughly correlates with the proportion of terraces, where we conlude that the active sites for the ORR are located, which is in agreement with earlier theoretical predictions by Nørskov, Rossmeisl and coworkers. Read more.     The Sabatier principle illustrated by catalytic H2O decomposition on metal surfaces       This work presents a classroom demonstration experiment for high school and first year college students demonstrating the interplay between theory and experiments in modern catalysis research.  The Sabatier principle is used to interpret a volcano curve and to demonstrate the predictive power of theoretical calculations together with experiments. The well-known heterogeneous catalysis experiment of decomposing H2O2 over metal and metal oxide catalysts is used to demonstrate this.                                                 Gas phase photocatalytic water splitting with Rh2-yCryO3/GaN:ZnO in μ-reactors Rh2-yCryO3/GaN:ZnO has been tested for gas phase overall photocatalytic water splitting dosing water vapor. Read more                                                                      The influence of surface defects on the methanation reaction over a Ru single crystal  The influence of monoatomic steps and defects on the methanation reaction over ruthenium has been investigated. Read more

Site Specificity in Femtosecond Laser Desorption of Neutral H Atoms from Graphite(0001) A model for the velocity distributions of Hydrogen desorbed from Graphite(0001) using a femtosecond laser pulse, reveals site specific peaks as well as information on the vibrational states of the adsorbed atoms. Read more

Origin of Power Laws for Reactions at Metal Surfaces Mediated by Hot Electrons A wide range of experiments have established that certain chemical reactions at metal surfaces can be driven by multiple hot electron mediated excitations of adsorbates. Read more

Controlled Directional Growth of TiO2 Nanotubes We demonstrate how the anodization direction and growth rate of vertically aligned, highly ordered TiO2 nanotube (NT) arrays can be controlled and manipulated by the local concentration of O2 in the electrolyte. This leads to the growth of highly active TiO2 NT arrays directly on nonconducting substrates in a single step. Read more

Alloys of platinum and early transition metals as oxygen reduction electrocatalysts Polymer electrolyte membrane fuel cells (PEMFC’s) could potentially replace the internal combustion engine as the main source of power for automotive vehicles. Running on hydrogen as a fuel, they produce no harmful emissions as their only waste product is water. However, several challenges need to be overcome to enable the widespread use of PEMFC’s. In particular, large efficiency losses are incurred by the slow kinetics of the oxygen reduction reaction (ORR), even when platinum is used as a catalyst. Read more

Hot electrons interacting with molecules. An central research topic at CINF is hot electron assisted chemistry at surfaces, which is studied both theoretically and experimentally. In this paper, we use time dependent density functional theory (TDDFT) to calculate how an energetic (“hot”) electron in a metal may interact with a molecule adsorbed on the surface. Read more

Hydrogen-Deuterium exchange The splitting of hydrogen on metal alloys is investigated by measuring the rate of the H-D exchange reaction. The figure shows the mass spectrometer signal for 3 AMU (HD) as a gas sampling device is scanned over a sample with 8 spots with varying amounts of Pt deposited on top of 50 Å Ru. Read more

Pt on Au electrocatalyst Surface Exchange Reaction Effects on Electrocatalysis of Au-Pt Systems. The Pt-on-Au system, surface exchange reactions play an important role in determining the dominant materials species available for electrocatalytic reactions such as hydrogen evolution (HER) and hydrogen oxidation (HOR). Read more

Cubane-type electrocatalysts  Hydrogen Evolution on supported [Mo3S4]4+ cubane-type electrocatalysts. Electrocatalytic properties of biomimetic supported incomplete cubane-type [Mo3S4]4+ clusters were investigated. Read more

Theory of excited molecules on surfaces  Delta self-consistent field method to obtain potential energy surfaces of excited molecules on surfaces. To calculate the influence of hot electrons on adsorbed molecules, it is necessary to go beyond standard Density Functional Theory (DFT) which by construction is limited to ground states only. Read more

Structure sensitivity of the methanation reaction A combination of extensive density functional theory calculations, ultra-high vacuum experiments on well-defined single crystals, and catalytic activity measurements on supported catalysts in a study of the dissociation mechanism of CO on Ni surfaces. Read more