{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:05:09Z","timestamp":1760148309934,"version":"build-2065373602"},"reference-count":34,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2023,4,19]],"date-time":"2023-04-19T00:00:00Z","timestamp":1681862400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002347","name":"Federal Ministry of Education and Research","doi-asserted-by":"publisher","award":["13FH6I02IA","ZW6-85007434","INST 196\/8-1 FUGG"],"award-info":[{"award-number":["13FH6I02IA","ZW6-85007434","INST 196\/8-1 FUGG"]}],"id":[{"id":"10.13039\/501100002347","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100008530","name":"European Regional Development Fund","doi-asserted-by":"publisher","award":["13FH6I02IA","ZW6-85007434","INST 196\/8-1 FUGG"],"award-info":[{"award-number":["13FH6I02IA","ZW6-85007434","INST 196\/8-1 FUGG"]}],"id":[{"id":"10.13039\/501100008530","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001659","name":"German Research Foundation","doi-asserted-by":"publisher","award":["13FH6I02IA","ZW6-85007434","INST 196\/8-1 FUGG"],"award-info":[{"award-number":["13FH6I02IA","ZW6-85007434","INST 196\/8-1 FUGG"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>The influence of plasma-reduction treatment on iron and copper compounds at different oxidation states was investigated in this study. For this purpose, reduction experiments were carried out with artificially generated patina on metal sheets and with metal salt crystals of iron(II) sulfate (FeSO4), iron(III) chloride (FeCl3), and copper(II) chloride (CuCl2), as well as with the metal salt thin films of these compounds. All the experiments were carried out under cold low-pressure microwave plasma conditions; the main focus was on plasma reduction at a low pressure in order to evaluate an implementable process in a parylene-coating device. Usually, plasma is used within the parylene-coating process as a supporting tool for adhesion improvement and micro-cleaning efforts. This article offers another useful application for implementing plasma treatment as a reactive medium in order to apply different functionalities by an alteration in the oxidation state. The effect of microwave plasmas on metal surfaces and metal composite materials has been widely studied. In contrast, this work deals with metal salt surfaces generated from a solution and the influence of microwave plasma on metal chlorides and sulfates. While the plasma reduction of metal compounds commonly succeeds with hydrogen-containing plasmas at high temperatures, this study shows a new reduction process that reduces iron salts at temperatures between 30 and 50 \u00b0C. A novelty of this study is the alteration in the redox state of the base and noble metal materials within a parylene-coating device with the help of an implemented microwave generator. Another novelty of this study is treating metal salt thin layers for reduction purposes in order to provide the opportunity to include subsequent coating experiments to create parylene metal multilayers. Another new aspect of this study is the adapted reduction process of thin metal salt layers consisting of either noble or base metals, with an air plasma pre-treatment prior to the hydrogen-containing plasma-reduction procedure.<\/jats:p>","DOI":"10.3390\/ma16083221","type":"journal-article","created":{"date-parts":[[2023,4,20]],"date-time":"2023-04-20T02:01:11Z","timestamp":1681956071000},"page":"3221","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Low-Pressure Microwave Plasma Reduction of Iron and Copper Salt Compounds at Low Temperatures for Oxidation State Alteration and Functional Applications"],"prefix":"10.3390","volume":"16","author":[{"given":"Mirco","family":"Weber","sequence":"first","affiliation":[{"name":"Faculty of Engineering and Health, HAWK University of Applied Sciences and Arts, Von-Ossietzky-Stra\u00dfe 98\/100, 37085 G\u00f6ttingen, Germany"},{"name":"Institute of Inorganic Chemistry, Georg August University of G\u00f6ttingen, Tammannstra\u00dfe 4, 37077 G\u00f6ttingen, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anna","family":"Scheglov","sequence":"additional","affiliation":[{"name":"Faculty of Engineering and Health, HAWK University of Applied Sciences and Arts, Von-Ossietzky-Stra\u00dfe 98\/100, 37085 G\u00f6ttingen, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wiebke","family":"D\u00f6rries","sequence":"additional","affiliation":[{"name":"Faculty of Engineering and Health, HAWK University of Applied Sciences and Arts, Von-Ossietzky-Stra\u00dfe 98\/100, 37085 G\u00f6ttingen, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Johann Benedikt","family":"Meyer","sequence":"additional","affiliation":[{"name":"Institute of Inorganic Chemistry, Georg August University of G\u00f6ttingen, Tammannstra\u00dfe 4, 37077 G\u00f6ttingen, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3425-9937","authenticated-orcid":false,"given":"Wolfgang","family":"Vi\u00f6l","sequence":"additional","affiliation":[{"name":"Faculty of Engineering and Health, HAWK University of Applied Sciences and Arts, Von-Ossietzky-Stra\u00dfe 98\/100, 37085 G\u00f6ttingen, Germany"},{"name":"Application Center for Plasma and Photonics, Fraunhofer Institute for Surface Engineering and Thin Films, Von-Ossietzky-Stra\u00dfe 100, 37085 G\u00f6ttingen, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,19]]},"reference":[{"key":"ref_1","unstructured":"Bertini, I., Gray, H.B., Stiefel, E.I., and Valentine, J.S. (2007). Biological Inorganic Chemistry: Structure and Reactivity, University Science Books. [1st ed.]."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Wiberg, E., and Holleman, A.F. (1971). Lehrbuch der Anorganischen Chemie, De Gruyter.","DOI":"10.1515\/9783111520285"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"727","DOI":"10.1007\/s10544-013-9758-8","article-title":"The effects of annealing on mechanical, chemical, and physical properties and structural stability of Parylene C","volume":"15","author":"Stieglitz","year":"2013","journal-title":"Biomed. Microdevices"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1016\/j.sna.2013.12.038","article-title":"Parylene-based 3D high performance folded multilayer inductors for wireless power transmission in implanted applications","volume":"208","author":"Sun","year":"2014","journal-title":"Sens. Actuators A Phys."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2000864","DOI":"10.1002\/aelm.202000864","article-title":"Homogeneous 3D Vertical Integration of Parylene-C Based Organic Flexible Resistive Memory on Standard CMOS Platform","volume":"7","author":"Chen","year":"2021","journal-title":"Adv. Electron. Mater."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"593","DOI":"10.1109\/TBCAS.2013.2282318","article-title":"Opto- \u03bcECoG array: A hybrid neural interface with transparent \u03bcECoG electrode array and integrated LEDs for optogenetics","volume":"7","author":"Kwon","year":"2013","journal-title":"IEEE Trans. Biomed. Circuits Syst."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Li, W., Rodger, D.C., Meng, E., Weiland, J.D., Humayun, M.S., and Tai, Y.-C. (2006, January 9\u201312). Flexible Parylene Packaged Intraocular Coil for Retinal Prostheses. Proceedings of the 2006 International Conference on Microtechnologies in Medicne and Biology, Okinawa, Japan.","DOI":"10.1109\/MMB.2006.251502"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"465","DOI":"10.1016\/j.snb.2010.06.059","article-title":"Low Voltage Electrowetting-on-Dielectric Platform using Multi-Layer Insulators","volume":"150","author":"Lin","year":"2010","journal-title":"Sens. Actuators B Chem."},{"key":"ref_9","unstructured":"Maeng, J., Kim, B.G., Ha, D., and Chappell, W.J. (2011, January 5\u201310). In Proceedings of the 2011 IEEE MTT-S International Microwave Symposium-MTT 2011, Baltimore, MD, USA. held as part of Microwave Week 2011."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"301","DOI":"10.1007\/BF02657422","article-title":"The parylene-aluminum multilayer interconnection system for wafer scale integration and wafer scale hybrid packaging","volume":"18","author":"Majid","year":"1989","journal-title":"J. Electron. Mater."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"897","DOI":"10.1243\/09544119JEIM543","article-title":"Zirconia-parylene multilayer thin films for enhanced fracture resistance of dental ceramics","volume":"223","author":"Teixeira","year":"2009","journal-title":"Proc. Inst. Mech. Eng. Part H J. Eng. Med."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1900296","DOI":"10.1002\/aelm.201900296","article-title":"Nonvolatile Electric Control of Exchange Bias by a Redox Transformation of the Ferromagnetic Layer","volume":"5","author":"Zehner","year":"2019","journal-title":"Adv. Electron. Mater."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"519","DOI":"10.1149\/08613.0519ecst","article-title":"Oxygen Reduction Reaction Properties for Dry-Process Synthesized Pt\/TaC x Nanoparticles","volume":"86","author":"Myochi","year":"2018","journal-title":"ECS Trans."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2101","DOI":"10.1039\/C8GC00200B","article-title":"Microplasma-assisted electrochemical synthesis of Co3O4 nanoparticles in absolute ethanol for energy applications","volume":"20","author":"Ni","year":"2018","journal-title":"Green Chem."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Tasche, D., Weber, M., Mrotzek, J., Gerhard, C., Wieneke, S., M\u00f6bius, W., H\u00f6fft, O., and Vi\u00f6l, W. (2020). In Situ Investigation of the Formation Kinematics of Plasma-Generated Silver Nanoparticles. Nanomaterials, 10.","DOI":"10.3390\/nano10030555"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"105206","DOI":"10.1088\/1361-6463\/aa5608","article-title":"A comparative study of the reduction of silver and gold salts in water by a cathodic microplasma electrode","volume":"50","author":"Vos","year":"2017","journal-title":"J. Phys. D Appl. Phys."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"215205","DOI":"10.1088\/1361-6463\/aabf2c","article-title":"Formation of metal (nano-)particles in drying latex films by means of a reducing plasma: A route to auto-stratification","volume":"51","author":"Bomhardt","year":"2018","journal-title":"J. Phys. D Appl. Phys."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2155","DOI":"10.1002\/adfm.201100093","article-title":"Direct Writing of Metal Nanoparticles by Localized Plasma Electrochemical Reduction of Metal Cations in Polymer Films","volume":"21","author":"Lee","year":"2011","journal-title":"Adv. Funct. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/j.cattod.2013.03.023","article-title":"Fabrication of Ir nanoparticle-based biosensors by plasma electrochemical reduction for enzyme-free detection of hydrogen peroxide","volume":"211","author":"Lee","year":"2013","journal-title":"Catal. Today"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1021\/acsanm.7b00125","article-title":"Low-Pressure Plasma Synthesis of Ni\/C Nanocatalysts from Solid Precursors: Influence of the Plasma Chemistry on the Morphology and Chemical State","volume":"1","author":"Haye","year":"2018","journal-title":"ACS Appl. Nano Mater."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"D818","DOI":"10.1149\/2.0541713jes","article-title":"Quantitative Study of Electrochemical Reduction of Ag+ to Ag Nanoparticles in Aqueous Solutions by a Plasma Cathode","volume":"164","author":"Ghosh","year":"2017","journal-title":"J. Electrochem. Soc."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1241","DOI":"10.1109\/TPS.2006.876486","article-title":"Treatment of Metal Surface by Atmospheric Microwave Plasma Jet","volume":"34","author":"Shin","year":"2006","journal-title":"IEEE Trans. Plasma Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s11090-013-9484-2","article-title":"Reduction of Oxide Minerals by Hydrogen Plasma: An Overview","volume":"34","author":"Sabat","year":"2014","journal-title":"Plasma Chem. Plasma Process."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1016\/j.cej.2017.05.114","article-title":"Non-thermal discharge plasma promoted redox transformation of arsenic(III) and chromium(VI) in an aqueous medium","volume":"329","author":"Chandana","year":"2017","journal-title":"Chem. Eng. J."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1139","DOI":"10.1071\/CH12163","article-title":"Cold Plasma Metallization of Supported Metal Salt Layers","volume":"65","author":"Crowther","year":"2012","journal-title":"Aust. J. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1885","DOI":"10.1016\/j.surfcoat.2009.01.018","article-title":"Surface-silvered polyimide films prepared by plasma-induced grafting of viologen and electroless plating","volume":"203","author":"Cui","year":"2009","journal-title":"Surf. Coat. Technol."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Weber, M., Vorobev, D., and Vi\u00f6l, W. (2022). Microwave Plasma-Enhanced Parylene-Metal Multilayer Design from Metal Salts. Nanomaterials, 12.","DOI":"10.3390\/nano12152540"},{"key":"ref_28","unstructured":"Martin, W.C., Musgrove, A., Kotochigova, S., Sansonetti, J.E., and Kramida, A. (2023, February 16). Ground Levels and Ionization Energies for the Neutral Atoms, NIST Standard Reference Database 111, Available online: https:\/\/www.nist.gov\/pml\/ground-levels-and-ionization-energies-neutral-atoms."},{"key":"ref_29","unstructured":"GESTIS-Stoffdatenbank (2023, February 16). Entry of Copper(I)-oxide. Available online: https:\/\/gestis.dguv.de\/data?name=004790."},{"key":"ref_30","unstructured":"GESTIS-Stoffdatenbank (2023, February 16). Entry of Copper(II)-oxide. Available online: https:\/\/gestis.dguv.de\/data?name=001990."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"G348","DOI":"10.1149\/1.1477209","article-title":"Effects of Plasma Activation on Hydrophilic Bonding of Si and SiO2","volume":"149","author":"Suni","year":"2002","journal-title":"J. Electrochem. Soc."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"138","DOI":"10.1116\/1.1247732","article-title":"CuCl by XPS","volume":"2","author":"Vasquez","year":"1993","journal-title":"Surf. Sci. Spectra"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"160","DOI":"10.1116\/1.1247736","article-title":"CuCl2 by XPS","volume":"2","author":"Vasquez","year":"1993","journal-title":"Surf. Sci. Spectra"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2441","DOI":"10.1016\/j.apsusc.2007.09.063","article-title":"Analysis of XPS spectra of Fe2+ and Fe3+ ions in oxide materials","volume":"254","author":"Yamashita","year":"2008","journal-title":"Appl. Surf. Sci."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/16\/8\/3221\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:18:51Z","timestamp":1760123931000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/16\/8\/3221"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,4,19]]},"references-count":34,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2023,4]]}},"alternative-id":["ma16083221"],"URL":"https:\/\/doi.org\/10.3390\/ma16083221","relation":{},"ISSN":["1996-1944"],"issn-type":[{"type":"electronic","value":"1996-1944"}],"subject":[],"published":{"date-parts":[[2023,4,19]]}}}