Exploring the versatility of liquid phase exfoliation: producing 2D nanosheets from talcum powder, cat litter and beach sand

Abstract Liquid phase exfoliation (LPE) has proven to be a versatile technique to produce uncharged 2D nanosheets from layered crystals. However, almost all studied starting materials consist of pure powder or crystals purchased from chemical suppliers. To test the true versatility of this process, we have attempted to process three starting materials with varying degrees of purity and composition. We subjected talcum powder (principle component: the layered compound talc), Fuller’s earth cat litter (known to contain layered silicate compounds, most notably palygorskite and montmorillonite/bentonite) and beach sand (suspected to contain small amounts of layered clays) to a standard LPE procedure (sonication in a surfactant solution followed by centrifugation). In all cases, we produced dispersions containing large quantities of nanosheets with almost all non-nanosheet material removed by the centrifugation step. Powder x-ray diffraction identified the nanosheets produced to be talc, a bentonite/palygorskite mixture and mica for the three starting materials respectively. Particularly interesting is the fact that bentonite, palygorskite and mica sheets are charged and are always accompanied by charge balancing counterions. We believe this is the first example of LPE being used to exfoliate and purify charged layered crystals.