Prof. Brian Laird named December 2023 Sutton Family Research Impact Award recipient

The Department of Chemistry congratulates Professor Brian Laird on receiving the December 2023 Sutton Family Research Impact Award!

The Sutton Award is a monthly competition among chemistry faculty. Every month, the Chemistry Department Chair and Associate Chairs review the peer-reviewed papers published by chemistry faculty from the three previous months to select a winner. The recipient receives a $500 cash prize and is featured on the departmental website.

For a full list of winners, visit our Sutton Family Research Impact Award webpage.

Generation of Amorphous Silica Surfaces with Controlled Roughness

By Nuong “Joyce” Nguyen and Brian B. Laird

Published in J. Phys. Chem. A., 127, 9831-9841 (2023)

Amorphous silica (a-SiO₂) surfaces, when grafted with select metals onto their surface, can act as useful heterogeneous catalysts. From a molecular modeling perspective, one challenge has been generating a-SiO₂ slab models with controllable surface roughness to facilitate the study of the effect of surface structure on the material properties. Previous computational methods either generate relatively flat surfaces or periodically corrugated surfaces that do not mimic the full range of potential surface roughness of the amorphous silica material. In this work, we present a new method, inspired by the capillary fluctuation theory of interfaces, in which rough silica slabs are generated by cleaving a bulk amorphous sample using a randomly generated cleaving surfaces with controlled roughness that can be tuned by varying a surface roughness parameter α – this is in contrast to the usual procedure to create the surfaces from bulk silica using a flat cleaving plane. Using a standard model of silica, we create a large number of silica slabs using cleaving surfaces of varying roughness (α). These surfaces are then characterized to determine their roughness and surface structure. This analysis shows a higher concentration of surface defects as the surface roughness increases. To examine the effect of the roughness on surface reactivity, we re-equilibriate a subset of these slabs using a simulation model that allows for reaction (ReaxFF ) and then expose the slabs to water to observe the formation of surface silanol groups (-Si-OH) We observe that the rougher surfaces exhibit higher silanol concentrations as well as bimodal surface acidity.

Caption: A technique for the generation of stochastically rough amorphous silica surfaces with tunable roughness for molecular simulation is presented. Graphic shows the difference among planar, corrugated and stochastically rough surfaces, as well as examples of silica slabs of varying roughness produced by the method and an example of a rough surface functionalized with silanol groups.