Insights into the Solution Processing of Non-van der Waals Boron Carbide.

Exfoliation of non-layered materials is crucial to unleash their enormous potential in wide range of applications. However, the presence of strong non-van der Waals interactions in all three dimensions makes exfoliation challenging. Boron carbide (B4C), known for its high hardness, holds great potential for diverse applications. In this work, B4C is exfoliated in 29 solvents to determine its Hansen solubility parameters (HSP) and understand the dispersion stability. The experimentally determined HSP values are 19.6, 15.3 and 15.1 MPa1/2 for dispersive interactions (δD), polar interactions (δP) and hydrogen bonding interactions (δH), respectively. Subsequently, in situ dispersion stability is analyzed qualitatively and quantitatively from the space-time resolved extinction profiles employing an analytical centrifuge. The sedimentation kinetics of B4C dispersions are analyzed using instability index, integral extinction and sedimentation velocity. B4C dispersions in solvents like ε-caprolactone, isopropyl alcohol, propylene carbonate and formamide exhibited excellent stability. Additionally, B4C nanosheets are utilized to investigate their field emission properties. These nanosheets exhibit a turn-on electric field of 3.35 V/μm at an emission current density of 1 μA cm-2, and it delivered a large emission current density of ~ 375 μA cm-2 at an applied electric field of 5.7 V/μm.