Plasma-assisted electrolytic synthesis of In(OH)3 nanocubes for thermal transformation into In2O3 nanocubes with a controllable Sn content

In addition to conventional wet-chemical methods for producing Sn-doped indium oxide (ITO) nanostructures, structural transformation from an ionic compound of indium hydroxide (In(OH)3) into indium oxide (In2O3) is a facile route for tailoring the dimensions, morphologies and compositions of In2O3 nanostructures. As a novel wet-chemical approach for the synthesis of In(OH)3 nanostructures, here we report a plasma-assisted electrolytic process where the In3+ and Sn4+ generated by plasma discharges on the surface of an In/Sn alloy anode hydroxylate, nucleate and grow to form single crystal In(OH)3 nanocubes. It was found that the In(OH)3 nanocubes reconstructively decomposed into small crystallites of bixbyite-type c-In2O3 with a diameter of ∼5–10 nm during the thermal transformation while the parent cube-shaped morphology of the In(OH)3 nanocubes remained unchanged. Compositional analysis revealed that the content of Sn in the final ITO nanocube product could be effectively controlled by the starting In/Sn ratio of the alloy anode. As a result, the doping-level of Sn significantly influenced the electrical conductivity of the ITO nanocubes with the optimal conductivity of 10.47 S cm−1 with a 15 wt% Sn content. The liquid-phase plasma technique is cost-effective and a continual process, and a high yield of 3.6 g hour−1 could be achieved in our simple lab-scale synthetic setup, suggesting great potential for industrial mass-production of high-quality ITO nanoparticles.