Facile preparation of NH2-functionalized black phosphorene for the electrocatalytic hydrogen evolution reaction

A new facile and green solid exfoliation method using urea-assisted ball milling is reported here to prepare NH2-functionalized few-layer black phosphorus (BP) nanosheets. The thickness of the obtained nanosheets is about 2.15-4.87 nm. The NH2-BP nanosheets exhibit enhanced electrocatalytic hydrogen evolution reaction (HER) performance with an overpotential of 290 mV at -10 mA cm(-2), a Tafel slope of 63 mV dec(-1) and a turnover frequency of 3.21 s(-1) at an over-potential of 290 mV, which drastically surpass those of the bulk BP. This electrocatalytic activity of NH2-BP nanosheets in alkaline electrolyte greatly outperforms that in acidic electrolyte, making it a promising metal-free HER catalyst.