2D ternary oxides – a new platform for substrate bound 2D materials

By Andy Massey on June 30, 2017

Today’s blog post comes from a group who recently published in Journal of Physics: Condensed Matter as part of the ongoing Special Issue on the Fundamentals of chemical functionalities at oxide interfaces. This Special Issue is aimed at displaying recent cutting-edge research into synergies between multi-component materials in several fields of catalysis, ranging from gas-solid reactions to electrocatalytic processes, and is being put together in collaboration with Guest Editors Prof. Stefano Agnoli and Prof. Matthias Batzill. Below, Doudin et al. explain in their own words their research into synthesis of two-dimensional ternary oxide nanolayers on a Pd(1 0 0) surface.

Figure 1: (a) Schematics of the preparation approach of 2D ternary MWO_x oxide layers; 2D MnWO_x phases on Pd(100) prepared in oxygen-rich (b) and oxygen-poor (c) environments. The left panels are STM images (b: 8×8 nm₂, 0.1 V, 50 pA, c: 7×7 nm₂, 0.3 V, 300 pA) and the right panels are structure models (top and side views) of the corresponding Mn₄W₂O₁₁ (b) and MnWO₃ (c) phases. Pd atoms are in gray, Mn atoms are in green, O atoms are in red and W atoms are in blue. Figure adapted from J. Phys.: Condens. Matter 29 234004 © Copyright 2017 IOP Publishing

The field of two-dimensional (2D) materials is continuously expanding due to their unique physical and chemical properties and their tremendous potential for applications in the emerging nanotechnologies. Amongst the plethora of 2D materials, 2D oxides stand out in creating new structure-property-function relationships, leading to a variety of applications as ultrathin capacitors and batteries, gas sensors, fuel cells, electronic and spintronic devices, and nanocatalysts. Here we present fundamental studies to generate a microscopic understanding of the heteroepitaxial growth and the properties of 2D ternary oxides on metal surfaces. Ternary and complex multi-component oxides have raised increasing interest recently as a result of their broad range of structural and compositional degrees of freedom and their related functionalities. In our work, we explore the structure-property relationship of artificially created 2D tungstate phases grown on noble metal single crystal surfaces and report a new fabrication strategy using on-surface synthesis.

The successful implementation of this new preparation method utilizes the on-surface solid state chemical reaction between well-defined 2D binary metal oxide and tungsten oxide phases (Fig. 1a) to create structurally well ordered 2D MnWO_x and FeWO_x tungstate layers on Pd(100) surfaces. The corresponding bulk compounds, MnWO₄ (huebnerite) and FeWO₄ (ferberite), are important materials with potential applications in photocatalysis, battery electrodes, magnetism and as multiferroics. We find that the structure and stoichiometry of the MnWO_x and FeWO_x phases on Pd(100) depend critically on the chemical potential of oxygen during preparation, ranging from an oxygen-rich layered hexagonal phase (Fig. 1b), weakly coupled to the substrate, to oxygen-poor bilayer commensurate structures (Fig. 1c). These 2D ternary oxides support completely different building architectures with no correspondence in the bulk, as a result of interfacial interactions and vertical confinement. Our model studies may open up exciting perspectives in the field of ternary oxides and could be transformative in creating new areas of research in more complex oxide systems.

Read the full Special Issue Article HERE

Or find out more about the Special Issue itself HERE

About the authors

Nassar Doudin and David Kuhness are former PhD students in the group of Prof. Svetlozar Surnev in Graz, and are presently Post-Doc fellows at the Pacific Northwest National Laboratory, Richland, Washington, USA, and at the Fritz Haber Institute of the Max Planck Society, Berlin, Germany, respectively.

Matthias Blatnik is a PhD student in the group of Prof. Svetlozar Surnev.

Falko P. Netzer is Professor Emeritus at the Institute of Physics of the Karl-Franzens University Graz. He led the Surface Science group in Graz over the last 25 years and initiated here the research on 2D oxide materials.

Svetlozar Surnev is Associate Professor at the Institute of Physics of the Karl-Franzens University Graz. His research is mainly focused on the fabrication and surface properties characterization of oxide nanostructures on metal surfaces.

This work is licensed under a Creative Commons Attribution 3.0 Unported License