Redox dynamics of 2D crystalline vanadium oxide phases on high-index anatase facets.

Vanadium oxides exist in a multitude of phases with varying structure and stoichiometry. This abundance of phases can be extended through the use of other oxides as supports, and through redox treatments. However, the combined effects of different supports and redox treatments can be difficult to identify, particularly when present as different terminating facets on nanoparticles.

Probing surface-sensitive redox properties of VO/TiO catalyst nanoparticles.

Redox processes of oxide materials are fundamental in catalysis. These processes depend on the surface structure and stoichiometry of the oxide and are therefore expected to vary between surface facets. However, there is a lack of direct measurements of redox properties on the nanoscale for analysing the importance of such faceting effects in technical materials.

Ab Initio Cyclic Voltammetry on Cu(111), Cu(100) and Cu(110) in Acidic, Neutral and Alkaline Solutions.

Electrochemical reactions depend on the electrochemical interface between the electrode surfaces and the electrolytes. To control and advance electrochemical reactions there is a need to develop realistic simulation models of the electrochemical interface to understand the interface from an atomistic point-of-view. Here we present a method for obtaining thermodynamic realistic interface structures, a procedure we use to derive specific coverages and to obtain ab initio simulated cyclic voltammograms.

Activity-Selectivity Trends in the Electrochemical Production of Hydrogen Peroxide over Single-Site Metal-Nitrogen-Carbon Catalysts.

Nitrogen-doped carbon materials featuring atomically dispersed metal cations (M-N-C) are an emerging family of materials with potential applications for electrocatalysis. The electrocatalytic activity of M-N-C materials toward four-electron oxygen reduction reaction (ORR) to HO is a mainstream line of research for replacing platinum-group-metal-based catalysts at the cathode of fuel cells. However, fundamental and practical aspects of their electrocatalytic activity toward two-electron ORR to HO, a future green "dream" process for chemical industry, remain poorly understood.

Electrochemical CO Reduction: A Property of the Electrochemical Interface.

Electrochemical CO reduction holds the promise to be a cornerstone for sustainable production of fuels and chemicals. However, the underlying understanding of the carbon-carbon coupling toward multiple-carbon products is not complete. Here we present thermodynamically realistic structures of the electrochemical interfaces, determined by explicit ab initio simulations.

Fundamental limitation of electrocatalytic methane conversion to methanol.

The electrochemical oxidation of methane to methanol at remote oil fields where methane is flared is the ultimate solution to harness this valuable energy resource. In this study we identify a fundamental surface catalytic limitation of this process in terms of a compromise between selectivity and activity, as oxygen evolution is a competing reaction. By investigating two classes of materials, rutile oxides and two-dimensional transition metal nitrides and carbides (MXenes), we find a linear relationship between the energy needed to activate methane, i.

Visualizing atomic-scale redox dynamics in vanadium oxide-based catalysts.

Surface redox processes involving oxygen atom exchange are fundamental in catalytic reactions mediated by metal oxides. These processes are often difficult to uncover due to changes in the surface stoichiometry and atomic arrangement. Here we employ high-resolution transmission electron microscopy to study vanadium oxide supported on titanium dioxide, which is of relevance as a catalyst in, e.

Facile embedding of single vanadium atoms at the anatase TiO(101) surface.

To understand the structure-reactivity relationships for mixed-metal oxide catalysts, well-defined systems are required. Mixtures of vanadia and titania (TiO) are of particular interest for application in heterogeneous catalysis, with TiO often acting as the support. By utilizing high-resolution scanning tunneling microscopy, we studied the interaction of vanadium (V) with the anatase TiO(101) surface in the sub-monolayer regime.

The reaction mechanism for the SCR process on monomer V(5+) sites and the effect of modified Brønsted acidity.

The energetics, structures and activity of a monomeric VO3H/TiO2(001) catalyst are investigated for the selective catalytic reduction (SCR) reaction by the use of density functional theory (DFT). Furthermore we study the influences of a dopant substitute in the TiO2 support and its effects on the known properties of the SCR system such as Brønsted acidity and reducibility of vanadium. We find for the reduction part of the SCR mechanism that it involves two Ti-O-V oxygen sites.