Hollow 1D copper oxide nanostructures with enhanced activity for catalytic reduction and photocatalytic degradation of organic pollutants

Abstract

Catalytic reduction and photocatalytic degradation are two important methods used for remediation of organic pollutants in waste water streams. Copper oxide is a fascinating material that can exhibit catalytic activity in both reactions. In this study we created various 1D copper oxide nanostructures using thermal oxidation of pre-synthesized copper nanowires. The process yield wire like, rod like and tubular wire like copper oxide nanostructures. The tubular morphology is formed by the classic Kirkendall effect. The BET surface area follows the order copper nanowire precursor > 400 °C annealed sample (tube structure) > 150 °C annealed sample (wire like structure)> 180 °C annealed sample (rod like structure). The efficiency of the synthesized materials in catalytic reduction reaction is tested using para nitrophenol reduction reaction. The visible light photocatalytic activity of the materials is tested using the degradation of methyl orange reaction. The synthesized materials show promising activity in both reactions. Interestingly, the copper oxide nanostructures outperform precursor copper nanowires, which possess the highest surface area, in both reactions. The sample calcined at 400 °C exhibits almost twice the catalytic activity than that of metallic copper in the hydride reduction reaction. The photocatalytic degradation rate exhibited by the same copper oxide nanostructure is 23 times higher than that of copper nanowires. The copper oxide nanostructure prepared in this study show catalytic activity almost an order of magnitude higher than copper oxide nanoparticles reported in literature. Catalytic cycling studies show that the synthesized materials show little reduction in property even after three cycles. The macroscopic wire like morphology, and high catalytic activity in reduction reaction and visible light photoactivity make the synthesized materials multipronged for applications like waste water remediation.