Synthesis of Uniform Bi₂WO₆‑Reduced Graphene Oxide Nanocomposites with Significantly Enhanced Photocatalytic Reduction Activity

Abstract

In\nthis work, the uniform B₂WO₆-reduced graphene\noxide (BWO–RGO) nanocomposites are prepared via electrostatic\nself-assembly of positively charged BWO with negatively charged GO\nsheets and then the composited GO is reduced via the hydrothermal\ntreatment. The close interfacial contact and strong electronic interaction\nbetween BWO and RGO are achieved by this facile and efficient self-assembly\nroute. Photocatalytic degradation of pollutant bisphenol A, selective\noxidation of benzyl alcohol, removal of heavy metal ion Cr­(VI), and\nselective reduction of 4-nitrophenol are selected as the probe reactions\nto investigate the photocatalytic activities of as-obtained BWO–RGO\nnanocomposites. The experimental results demonstrate the photocatalytic\nredox activities of BWO–RGO composites are predominantly dependent\non the energy levels of photoinduced electrons or holes. In particular,\nthe upshift of the valence band and conduction band edge of catalysts\ninduced by the electronic interaction between BWO and RGO has an inconsistent\ninfluence on the photocatalytic reduction and oxidation reactions,\nrespectively. As a result, the photocatalytic activity of reduction\nreactions is significantly enhanced, owing to the synergetic effect\nof the upshift of conduction band edge and the improved separation\nof photogenerated electrons/holes, while the oxidation ability of\nBWO–RGO nanocomposite is improved to a slight extent compared\nwith bare BWO. The energy levels of photogenerated carriers should\nbe the origins accounting for the different enhancement of photocatalytic\nactivities for the different reactions. According to the discussion,\none important conclusion can be drawn, that is, the results should\nbe analyzed on the basis of specific reactions when discussing the\neffect of graphene or RGO on the photocatalytic properties of semiconductor\nparticles.