Transparent Black Phosphous Nanosheet Film for Photoelectrochemical Watrer Oxidation

Abstract

Although monolayer black phosphorus (BP) and few-layer BP nanosheets (NSs) have been extensively studied as promisingalternatives to graphene, research has focused primarily on atomically thin-layered BP in an isolated form. In order to realize thepractical applications of BP-related devices, a BP film based on continuous networking of few-layer BP NSs should bedeveloped. In this study, a transparent BP film with high quality was fabricated via a vacuum filtration method. An oxygen-freewater solvent was used as an exfoliation medium to avoid significant oxidation of the few-layer BP NSs in liquid-phaseexfoliation. The exfoliation efficiency from bulk BP to the few-layer BP NSs was estimated at 22%, which is highly efficient forthe production of continuous BP film. The characteristics of the high-quality BP film were determined as 98% transparency,minimum oxidation of 18%, structural stability, and an appropriate bandgap of about 1.8 eV as a semiconductor layer. In order todemonstrate the potential of the BP film for photocatalytic activity, we performed photoelectrochemical water oxidation of thetransparent BP film. Although its performance should be improved for practical applications, the BP film could function as aphotoanode, which offers a new potential semiconductor in water oxidation. We believe that if the BP film is adequatelyengineered with other catalysts the photocatalytic activity of the BP film will be improved.