Role of graphene nanocomposite photocatalysts in photo-reduction of Cr (VI) for wastewater treatment

Among numerous heavy metals, hexavalent Chromium [Cr (VI)] place a potential threat and mostly seen in several industrial effluents such as leather tanning, printing, ceramics. For removal of Cr from waste water, reduction of Cr (VI) to Cr (III) is preferred due to less toxicity of Cr (III) than Cr (VI). Among various reduction processes, Cr (VI) reduction by photocatalysis is favoured owing to its greener approach and behaviour. Graphene nanocomposite photocatalysts show higher photo reduction efficiency due to large surface area and extraordinary electron conductance of graphene. As there is almost no resistance on the surface of graphene, so electrons move freely and faster resulting excellent surface charge transfer; therefore enhanced photocatalytic Cr (VI) reduction. We have systematically investigated the origin and enhancement of photo-reduction Cr (VI) by graphene nanocomposites photocatalysts. Graphene based metal oxides nanocomposites, metal sulphides, 0D/2D heterojunction nanocomposites, non-metallic nanocmposites, plasmonic nanocomposites and Z-scheme nanocomposites photocatalysts have been highlighted and discussed. (C) 2019 Elsevier Ltd. All rights reserved.

Automated summary

Hexavalent Chromium poses a potential threat in industrial effluents, and graphene nanocomposite photocatalysts demonstrate higher photo reduction efficiency in reducing Cr (VI) through photocatalysis.