Facile fabrication of alpha-FeOOH nanorod/RGO composite: a robust photocatalyst for reduction of Cr(VI) under visible light irradiation

Abstract

A facile one step hydrothermal route has been adopted for in situ deposition of alpha-FeOOH nanorods over reduced graphene oxide sheets (RGO) where sodium hydroxide plays a dual role in the growth of alpha-FeOOH nanorods and reduction of graphene oxide (GO) to RGO. The crystallographic, microscopic, and spectroscopic properties of the as-synthesized alpha-FeOOH nanorod/RGO composites were explored by XRD, Raman, DRUV-vis, PL, TRPL, XPS, FESEM, TEM, and photoelectrochemical measurement. The alpha-FeOOH nanorod/RGO composite displays superior photocatalytic activity towards the reduction of hexavalent chromium [Cr(VI)] compared with neat alpha-FeOOH nanorod under visible light irradiation. The extended pi-conjugated flat 2D layer of graphene plays a crucial role in enhancing the photocatalytic activity of alpha-FeOOH nanorod by channelizing the photoexcited electrons on its surface. This leads to minimization of the electron-hole recombination which is successfully derived from photoluminescence study, time-resolved photoluminescence spectra, and photoelectrochemical measurement of alpha-FeOOH nanorod/RGO composites. The time resolved decay measurements showed longer average decay time (<tau >) for 3 wt% RGO loaded alpha-FeOOH of the order of 4.13 ns, than that of the neat alpha-FeOOH (2.536 ns). The improved photocurrent generation (nearly three times higher than that of the neat alpha-FeOOH nanorod) and low photoluminescence (PL) intensity of alpha-FeOOH nanorod/RGO composite is a result of the well decoration and strong attachment of alpha-FeOOH nanorods over RGO sheets, which significantly enhance its photocatalytic activity.