Preparation of Ni(Zn)Cr-LDH/LDO coated magnetic-graphene composites using simulative electroplating wastewaters for oxygen evolution reaction

Abstract

Electroplating wastewaters (EWs) have to be treated due to their toxic property, which could bring many separation and economic problems. The generation of value-added products using low value and harmful EWs could decrease the economic cost on the treatment and the raw materials. In this work, polyaspartic acid modifying magnetic graphene composite (MG) was firstly prepared with promising magnetic separation and heavy metal ions uptake properties. Ni(Zn)-Cr layered double hydroxides coating magnetic-graphene composites (Ni(Zn)Cr-LDH/MG) were prepared by co-precipitation method using simulative electroplating wastewaters, which were further calcined to form layered double oxides (Ni(Zn)Cr-LDO/MG). The resulting materials were carefully examined by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometer and electrochemical techniques. The electro-catalysis of the resulting materials towards oxygen evolution reaction (OER) was investigated by various electrochemical methods in 1 M KOH. NiCr-LDO/MG formed at 500℃ showed promising electro-catalysis for OER, with good catalytic stability over long period of 50,000 s. The present results demonstrated that EWs could be reused to fabricating promising value-added catalyst on OER.