Anchoring of polymeric precursor on oxygen deficient ZnO nanotubes: A chelation assisted combined nucleation-growth-dissolution synthesis strategy

Abstract

A template-free method has been adopted to synthesize predominantly oxygen deficient and morphologically tuned zinc oxide nanotubes. A relatively simple sol-gel route was chosen for the same using zinc acetate dihydrate and beta-aminoethylamine as precursors and the feasibility of the photocatalytic activity of the nanotubes was analyzed comprehensively. Etching of the nanotubes was fine-tuned effortlessly by changing the ratio of precursor concentration during synthesis. Here, polymeric precursor plays multiple roles and controls the shape and roughness of the formed nanotubes by serving as a co-ordination assisted precipitation, dissolution, etching and reducing agent. Nonpolar, chelating bi-dentate polymeric precursor anchors both heterogeneous nucleation and dissolution controlled growth in single stretch. Oxygen deficient ZnO nanotubes with varying surface properties were obtained from zinc to beta-aminoethylamine ratio of 2:1, 1:2 and 1:1 (21ZE, 12ZE, 11ZE). Structure, morphology and optical properties of the ZnO nanotubes were systematically examined. Nanotubes with etched surface showed better photocatalytic activity in methylene blue degradation compared to those with non-etched surface. ZnO nanotubes synthesized from equimolar concentration of the precursors (11ZE) showed stable photocurrent in chronoamperometric study with more than 60 percentage degradation of methylene blue within 90min.