Red phosphorus as a novel visible-light-responsive and metal-free photocatalyst has attracted extensive attention in the area of energy conversion and environmental remediation. Herein, nano-sized red phosphorus photocatalyst was synthesized via a hydrothermal and ultrasonic method and used for reduction of Cr (VI) for the first time. The as-prepared photocatalysts were characterized by XRD, UV-Vis-DRS, XPS, SEM, TEM and photoelectrochemical measurements. Compared to bulk red phosphorus, nano-sized red phosphorus exhibit a significantly enhanced photocatalytic activity for reduction of Cr (VI) due to the greatly reduced charge transfer resistance and enhanced adsorption capability of Cr (VI). (C) 2018 Elsevier Inc. All rights reserved.