E.J. Broker Jr., R. Davenport, J.D. Batteas
Texas A&M University,
United States
Keywords: atomic force microscopy, graphene, 2D materials, surface chemistry, mechanochemistry
Summary:
Two-dimensional (2D) materials are an exciting class of compounds through which new reaction mechanisms can be elucidated, and scanning probe microscopy is one of many ways in which these materials can be characterized or modified to reach those ends. The use of mechanical force to drive chemical reactions on 2D materials like graphene is studied by combining relevant and widely utilized techniques such as Raman microspectroscopy and atomic force microscopy (AFM) with a specially designed 2D-Materials Strain Reactor (2D-MSR). This system was previously utilized to achieve a mechanochemical reaction between water and a strained graphene surface. The in situ capabilities of the 2D-MSR allow for temporally resolved spectral analysis and morphological characterization. This initial proof-of-concept reaction has now inspired an acoustically driven approach, whereby a tapping mode probe is used as a resonator in an attempt to induce standing waves in suspended graphene. These standing waves act as tunable modulators through which the graphene’s surface geometry can be favorably altered, allowing for controllable patterning and localized reactivity. The 2D-MSR is a platform which provides novel routes to exploring the effects of out-of-plane distortions and applied forces on the nanoscale while also facilitating the study of reaction energetics and kinetics through nanolithography and microspectroscopy. Moving forward, attention will turn to other 2D materials, such as the transition metal dichalcogenide molybdenum disulfide (MoS2), in hopes that the lubricious and optoelectronic properties of interest in such materials can be facilely modified or tuned depending on the requirements of desired applications.