Could you explain the significance of your article to the non-specialist?

The problem of metal-support interactions is of great importance to many fields, including coating technologies and heterogeneous catalysis. In most cases the materials are synthesized and used in the conditions, which are neither "clean", nor equilibrium. This makes many of the modern results obtained with sophisticated surface-science techniques hardly applicable to the "real" systems. In this work the classical method of contact angle measurement routinely used for gas bubbles and liquid drops was first successfully applied to crystalline copper nanoparticles supported on two different oxides in catalytic materials.

What has motivated you to conduct this work?

Our group has been involved in studying Cu-based catalytic materials for many years. With a variety of experimental techniques it has been shown that the strained state of metal particles affects the catalytic activity of these materials significantly. The strain may arise from different factors, including strong metal-support interaction (SMSI). That is why quantitative characterization of SMSI was always an important step and a challenge in our work. Since the metal particles in our materials seldom (or never) had the equilibrium shape, the Wulff analysis widely used in surface science was not applicable. In spite of some limitations and drawbacks, the classic technique of contact angle measurement proved to be useful for the systems that are not under thermodynamic control.

Where do you see this work developing in the future?

We think that this work may be further developed in the field of heterogeneous catalysis research.

Are there any particular challenges facing future research in this area?

In the present state the method developed here can be used for semi-quantitative trend comparison. To take it to the fully quantitative level, a careful analysis of various factors affecting the results and a comparison of the results with those obtained with other methods (such as the surface-science techniques) is requir