A new graphene bottom ash geopolymeric composite for photocatalytic H-2 production and degradation of dyeing wastewater

摘要

A novel Mn2+-doped and CuO loaded graphene bottom ash-based geopolymeric (Mn2+-CuO/GBAG) composite was firstly synthesized by a four-step experiment of alkaline activated geopolymerization, ion exchange, co-impregnation and calcinations. The composite was employed as the photocatalyst for production of hydrogen by solar photo-reduction and degradation of dye by photo-oxidation. XRD, XPS and N-2 adsorption-desorption equilibrium isotherms results revealed that Mn2+ ions implant into the lattice of CuO, and the CuO in the form of tenorite with average particle size of about 20 nm dispersed on the surface or inserted micro and mesoporous channels. The Mn2+-15CuO/GBAG composite exhibited the highest H-2 yield of 2853.7 mu mol g(-1). It was found that the activity of photocatalytic reduction for hydrogen production was proportional to the contents of the Mn2+ doping and CuO loading, and inverse proportional to the intensity of photoluminescence due to the enhancement of separation efficiency of photogenerated electron hole pairs. The Mn2+-15CuO/GBAG composite showed the highest photocatalytic degradation activity of 100% for direct sky blue 5B dye, and the degradation reaction fitted the first-order kinetics. A probable mechanism of photocatalytic reduction and oxidation was proposed in the paper. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.