Ag/black phosphorus composite based on multilayer black phosphorus: Its preparation and photocatalytic methyl orange degradation performance

Abstract

In this study, a new method is proposed for the preparation of Ag/black phosphorus composite in an anhydrous system. Before the preparation, black phosphorus (BP) bulk is firstly preprocessed by a wet ball milling method combined with sodium hydroxide, so that BP can be functionalized and a large proportion (80%) of micro-multilayer BP flakes (MBP) with hydroxyl groups can be used. Then the addition of ethylene glycol and polyvinylpyrrolidone into the synthesis system prevents agglomeration of hydroxylated MBP flakes and enables the uniform distribution of Ag+ on BP flakes, thereby yielding an Ag/MBP composite with Ag nanoparticles uniformly dispersed on BP flakes. XRD, Raman, and XPS results indicate that the BP with its lattice structure is retained in Ag/MBP. In fact, neither Ag nor hydroxylated MBP shows photocatalytic activity; however, in the presence of Ag/MBP, methyl orange (MO) is completely degraded within 85 min under irradiation with light of wavelength 300–2500 nm. The well dispersed Ag nanoparticles enhance the absorption of high-intensity light and facilitate the transfer of photogenerated e− from BP, finally facilitating the separation of h+ and e−. Superoxide radical (·O2−) and holes (h+) are identified to be the active radicals directly involved in the degradation of MO.