Hydrothermal synthesis of a 3-D SnO2 nanoflower electrode with C and N co-doped interlayer for the degradation of real cyanide wastewater

[Display omitted] •Constructed Ti/TiONC/Sb-SnO2-NFs electrode by hydrothermal method.•The TiONC interlayer enhanced electrocatalytic activity and stability of electrode.•The Ti/TiONC/Sb-SnO2-NFs electrode had high degradation efficiency for cyanides.•The possible mechanism of electrocatalytic degradation of cyanides was proposed. In this study, a novel three-dimensional SnO2 nanoflower structure (SnO2-NFs) with carbon and nitrogen co-loaded interlayer was prepared via hydrothermal method and used to remove metal-cyanide complexes from real cyanide wastewater. Compared with a pure SnO2-NFs electrode, the C and N co-doped interlayer resulted in the electrode providing a higher oxygen evolution potential (2.30 V vs SCE), smaller crystal size, larger active specific surface area and lower charge transfer resistance. A lifetime acceleration test showed that the fortified lifetime of this new electrode was about 38 times that of the Ti/Sb-SnO2 electrode prepared by the conventional thermal decomposition method. Hence, the Ti/TiONC/Sb-SnO2-NFs electrode exhibited good electrocatalytic activity and stability. The electron spin resonance analysis and quenching of active radical experiments revealed that the generation of •OH, 1O2, •O2− and SO4•− species in this system, among them •OH was the most active species for the oxidation of cyanides. Further analysis using X-ray diffraction and X-ray photoelectron spectroscopy showed that cyanide was finally oxidized to CO2 and NO3–, and the released Cu(I) was mainly deposited on the cathode surface in the form of Cu0 and CuO.