Electrochemistry of Solvent-Exfoliated Red Phosphorus Nanosheets

Commercially available and stable red phosphorus (RP) is a promising material to produce two-dimensional RP nanomaterials. In this work, RP nanosheets are produced using a liquid-phase exfoliation approach with aid of ultrasonication. The RP nanosheets exfoliated in the solvents of ultrapure water, isopropanol, and N,N-dimethylformamide (DMF) exhibit different sizes and thicknesses. More uniform and thinner RP nanosheets are obtained in DMF (ERP-DMF), due to optimized surface energies between RP nanosheets and DMF. These RP nanosheets show varied activities towards electrooxidation of one case molecule of 4-nitrophenol (4-NP). ERP-DMF features a larger active area and a higher electron transfer rate than those produced in water and isopropanol. Sensitive, reproducible, stable, and selective monitoring of 4-NP is then achieved using ERP-DMF as the sensing material. This study provides a general approach to produce two-dimensional nanomaterials from bulk materials as well as the guidance to explore their potential applications.