doi:10.1038/s41598-019-47704-5engAzevedo, JoãoFernández-García, M.P.Magén, CésarMendes, AdélioAraújo, João P.Sousa, Célia T.Double-walled iron oxide nanotubes via selective chemical etching and Kirkendall processART-2019-113546Double-walled oxide nanotube structures are interesting for a wide range of applications, from photocatalysis to drug delivery. In this work, a progressive oxidation method to fabricate double-walled nanotube structures is reported in detail. The approach is based on the electrodeposition of metallic iron nanowires, in porous alumina templates, followed by a selective chemical etching, nanoscale Kirkendall effect, a fast oxidation and out-diffusion of the metallic core structure during thermal annealing. To validate the formation mechanism of such core-shell structure, chemical composition and atomic structure were assessed. The resulting hematite nanotubes have a high degree of uniformity, along several microns, and a nanoscopic double-walled structure.2019http://zaguan.unizar.es/record/9683110.1038/s41598-019-47704-5http://zaguan.unizar.es/record/96831oai:zaguan.unizar.es:96831info:eu-repo/grantAgreement/ES/FEDER/POCI-01-0141-032527info:eu-repo/grantAgreement/ES/FEDER/POCI-01-0145-006939info:eu-repo/grantAgreement/ES/FEDER/POCI-01-0145-016387info:eu-repo/grantAgreement/ES/FEDER/POCI-01-0145-030510info:eu-repo/grantAgreement/EC/H2020/734801/EU/Novel magnetic nanostructures for medical applications/MAGNAMEDThis project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 734801-MAGNAMEDinfo:eu-repo/grantAgreement/ES/MINECO/RTI2018-094683-B-C52Scientific Reports 9 (2019), 11994 [8 pp]byhttp://creativecommons.org/licenses/by/3.0/es/info:eu-repo/semantics/openAccess