A University of Birmingham research team has developed a novel vibration-based technique for producing graphene and other 2D materials that achieves production rates over six times higher than current methods while functioning at concentrations up to 1000 mg mL⁻¹. The work demonstrates a sustainable approach that operates at room temperature without requiring toxic solvents.
The researchers employed a resonant acoustic mixing system that vibrates dispersions at frequencies of 60 Hz and accelerations up to 100g, delivering energy density two orders of magnitude lower than shear exfoliation. Using electron microscopy combined with multiphase computational models, the team revealed that vibrational motion causes graphite particles to fold at the edges, followed by particle fracture and sheet peeling. In the liquid phase, mechanical forces exceed the interlayer binding energy between layers, facilitating molecular-scale sheet delamination into atomically thin graphene.
Unlike conventional liquid phase exfoliation methods such as shear mixing and sonication, which are sensitive to solid loadings and mixture rheology, vibrational exfoliation maintains consistent yields across a broad range of concentrations. Dr. Jason Stafford from the Department of Mechanical Engineering, who led the team, said: "Our work shows a new way of making 2D materials that overcomes the production capacity issues of current methods, while simultaneously embedding sustainable manufacturing practices". The earliest stages of graphene production were detected as early as five minutes, and spectroscopic analyses confirmed the approach does not introduce defects into the graphene nanosheets.
The team successfully applied the technique to other layered materials including hexagonal boron nitride (h-BN), molybdenum disulfide (MoS₂), and tungsten disulfide (WS₂) . While these materials present challenges due to their larger binding energies compared to graphite, the researchers identified optimization opportunities through solvent design, dispersing agents, vessel features, and acceleration level adjustments.
The researchers demonstrated the method using water and tannic acid rather than toxic solvents, emphasizing sustainability and low cost. Dr. Stafford said, "By creating alternate, more sustainable synthetic routes for these exciting materials, we have an opportunity to lower the barrier for industrial translation. This will help facilitate future electronic devices, composites, and catalysts, while also avoiding unintended environmental consequences as production is scaled up".
A patent application was filed through University of Birmingham Enterprise for this high-throughput method for 2D and nanomaterial processing. The research team is seeking commercial partners for licensing and further development of the technology.
