UW Professors Recently Publish Two Research Papers in Journal of American Chemical Society

Two-dimensional (2D) materials, such as graphene, have numerous practical applications in areas that include electronics in transistors, sensors and detectors; as battery and fuel cell electrodes; and as nanocomposites.

Three faculty members in the University of Wyoming Department of Chemistry were part of back-to-back articles that focused on 2D materials research that was recently published in the Journal of the American Chemical Society, the flagship journal of the American Chemical Society.

Laura de Sousa Oliveira, an assistant professor of chemistry and the UW Derecho Professor; John Hoberg, a UW professor of chemistry; and Bruce Parkinson, a UW professor emeritus of chemistry; were authors on both papers.

Two-dimensional materials grow via nucleation of a small sheet that then expand in two dimensions with the addition of more atoms or molecules on the edges of the 2D island. As the 2D islands grow, they can eventually join with other islands along the boundaries, overlap at the boundaries or are subjected to a variety of defects.

The first paper, titled "Engineering Screw Dislocations in Covalent Organic Frameworks," was published in late September. Hoberg was the corresponding author. The paper's authors reported the first-ever screw dislocation in these 2D materials, also known as covalent organic frameworks.

A screw dislocation occurs when the growing island tilts vertically up or down, such that growth continues as a helical, or spiral shape, to produce a screw or spiral staircase. This result produces three-dimensionality on the boundaries of the 2D material.

"By controlling the growth of screw dislocations in 2D materials, unique architectures and properties can result that influence physical and electronic properties of the material," Hoberg says.

The researchers were able to synthetically build the 2D materials. Using UW's Center for Advanced Scientific Instrumentation equipment, the research group was able to locate these screws throughout the 2D-covalent organic framework materials. These high-resolution images appeared as atomic-sized seashells that provided direct evidence of the screw dislocations.

UW students who contributed to the research are Kira Coe-Sessions, a Ph.D. student from Sheridan studying chemistry; Michael Wenzel, a Ph.D. student from Mount Horeb, Wis., studying chemistry; Alathea Davies, a Ph.D. student from Moscow, Idaho, studying chemistry; and Taylor Kelsey, a spring 2024 UW graduate from Englewood, Colo., with a bachelor's degree in chemistry.

Jonathan Brant, a UW professor of civil and architectural engineering, and Bhausaheb Dhokale, a UW research scientist, also were part of the study.

The study was funded by grants from the National Science Foundation's (NSF) Designing Materials to Revolutionize and Engineer our Future (DMREF), UW Center of Energy Materials and the National Center for Atmospheric Research (NCAR)-Wyoming Supercomputing Center.

The second paper, titled "Functionalized Graphene via a One-Pot Reaction Enabling Exact Pore Sizes, Modifiable Pore Functionalization and Precision Doping," was published in late November. Hoberg and de Sousa Oliveira were corresponding authors on the paper.

During this study, researchers incorporated a small synthetic modification and were able to control the 2D growth, such that planar, graphene-like materials were constructed. Graphene is a single layer of carbon atoms arranged in 2D honeycombs that has revolutionized the field of material science with its extraordinary electrical conductivity and mechanical strength, Hoberg says.

"Previous researchers have found that, when attempting to modify graphene to change its properties, a host of problems arise that produce random-sized holes and only incremental incorporation of other desired elements, which are randomly placed in the honeycomb structure," Hoberg explains. "These modifications generally change graphene's behavior, such as transforming it from a conductor to an insulator."

During their work, UW researchers synthesized a new, highly ordered, 2D nanoporous graphene-like material in which exact pore sizes were incorporated with 100 percent of the desired elements -- such as nitrogen and oxygen -- in the structure. The electronic behavior of these new graphitic materials was shown to be similar to graphene itself.

Masoumeh Gahrouei, a Ph.D. student from Isfahan, Iran, studying chemistry; Nikiphoros Vlastos, a junior from Casper majoring in physics and environmental science; Jordan Klaassen, a spring 2024 UW graduate from Gillette who received his bachelor's degree in chemistry; Coe-Sessions, Davies, Wenzel and Dhokale all contributed to this study.

The study was funded by grants from NSF's DMREF, UW Center of Energy Materials, the NCAR-Wyoming Supercomputing Center and the Department of Energy's Office of Basic Energy Sciences.