PbO2decorated ZnO-TiO2core-shell nanoflower structures by zinc anodising for photo- and anodic degradation of Reactive Black-5 dye

Abstract This work shows that metallic zinc can be used as a low-cost substrate or electrode for photocatalyst and electrocatalyst use by anodising in mild bicarbonate solution. Electrochemical anodising was used to produce ZnO nanowires by controlling operational conditions and dip-coating the anodised surface with TiO 2 to produce a core-shell coating with photocatalytic properties. The PbO 2, which is known as good electrocatalyst, was electrodeposited over the ZnO-TiO 2 core-shell structure to alter its surface for electrocatalytic degradation of dye. The electrochemical and photocatalytic behaviours of the coatings were analysed for the removal of RB-5 dye as model pollutant. For the ZnO-TiO 2 core-shell, the photocatalytic removal mechanism was driven by the heterojunction photocatalytic effect of photocatalytically active anatase TiO 2 and wurtzite ZnO. Photocatalysis was switched to electrocatalytic behaviour after incorporation of PbO 2. Although the UV light might be blocked by PbO 2 , the electrochemical degradation was enhanced due to the creation of · OH free radicals over the PbO 2 particles decorating a ZnO-TiO 2 core-shell composite coating.