{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,3]],"date-time":"2026-03-03T12:33:40Z","timestamp":1772541220254,"version":"3.50.1"},"reference-count":29,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2021,9,27]],"date-time":"2021-09-27T00:00:00Z","timestamp":1632700800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nanomaterials"],"abstract":"<jats:p>Dielectric properties and spectral dependence of the photocatalytic constant of Co doped P25 Degussa powder were studied. Doping of TiO2 matrix with cobalt was achieved by precipitation method using of Tris(diethylditiocarbamate)Co(III) precursor (CoDtc\u2013Co[(C2H5)2NCS2]3). Five different Co contents with nominal Co\/Ti atomic ratios of 0.005, 0.01, 0.02, 0.05 and 0.10 were chosen. Along with TiO2:Co samples, a few samples of nanopowders prepared by Sol-Gel method were also studied. As it follows from XPS and NMR studies, there is a concentration limit (TiO2:0.1Co) where cobalt atoms can be uniformly distributed across the TiO2 matrix before metallic clusters start to form. It was also shown that CoTiO3 phases are formed during annealing at high temperatures. From the temperature dependence of the dielectric constant it can be concluded that the relaxation processes still take place even at temperatures below 400 \u00b0C and that oxygen defect Ti\u2013O octahedron reorientation take place at higher temperatures. The spectral dependency of the photocatalytic constant reveals the presence of some electronic states inside the energy gap of TiO2 for all nanopowdered samples.<\/jats:p>","DOI":"10.3390\/nano11102519","type":"journal-article","created":{"date-parts":[[2021,9,27]],"date-time":"2021-09-27T21:40:30Z","timestamp":1632778830000},"page":"2519","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Dielectric Properties and Spectral Characteristics of Photocatalytic Constant of TiO2 Nanoparticles Doped with Cobalt"],"prefix":"10.3390","volume":"11","author":[{"given":"Valentin G.","family":"Bessergenev","sequence":"first","affiliation":[{"name":"Centre of Marine Sciences (CCMAR), Campus de Gambelas, Universidade do Algarve, FCT, 8005-139 Faro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8480-617X","authenticated-orcid":false,"given":"Jos\u00e9 F.","family":"Mariano","sequence":"additional","affiliation":[{"name":"CeFEMA, Campus de Gambelas, Universidade do Algarve, FCT, 8005-139 Faro, Portugal"}]},{"given":"Maria Concei\u00e7\u00e3o","family":"Mateus","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o em Qu\u00edmica do Algarve (CIQA), Campus de Gambelas, Universidade do Algarve, FCT, 8005-139 Faro, Portugal"}]},{"given":"Jo\u00e3o P.","family":"Louren\u00e7o","sequence":"additional","affiliation":[{"name":"Centro de Investiga\u00e7\u00e3o em Qu\u00edmica do Algarve (CIQA), Campus de Gambelas, Universidade do Algarve, FCT, 8005-139 Faro, Portugal"},{"name":"Centro de Qu\u00edmica Estrutural, Instituto Superior T\u00e9cnico, Universidade de Lisboa, Av. Rovisco Pais, 1096-001 Lisbon, Portugal"}]},{"given":"Adwaa","family":"Ahmed","sequence":"additional","affiliation":[{"name":"Institute of Physics, University of Rostock, 18055 Rostock, Germany"}]},{"given":"Martin","family":"Hantusch","sequence":"additional","affiliation":[{"name":"IFW Dresden, Helmholtzstra\u00dfe 20, 01069 Dresden, Germany"}]},{"given":"Eberhard","family":"Burkel","sequence":"additional","affiliation":[{"name":"Institute of Physics, University of Rostock, 18055 Rostock, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3131-4219","authenticated-orcid":false,"given":"Ana Maria","family":"Botelho do Rego","sequence":"additional","affiliation":[{"name":"CQFM, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"854","DOI":"10.1126\/science.1056186","article-title":"Room-temperature ferromagnetism in transparent transition metal-doped titanium dioxide","volume":"291","author":"Matsumoto","year":"2001","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1016\/S1369-7021(02)05423-8","article-title":"A potential role in spintronic","volume":"5","author":"Chambers","year":"2002","journal-title":"Mater. Today"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1016\/S0920-5861(99)00107-8","article-title":"Heterogeneous photocatalysis: Fundamental and applications to the removal of various types of aqueous pollutants","volume":"53","author":"Herrmann","year":"1999","journal-title":"Catal. Today"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1016\/j.cattod.2014.07.009","article-title":"Theory of surface chemistry and reactivity of reducible oxides","volume":"244","author":"Tranca","year":"2015","journal-title":"Catal. Today"},{"key":"ref_5","first-page":"1285","article-title":"Low-temperature sintering and microwave dielectric properties of TiO2-based LTCC materials","volume":"21","author":"Pang","year":"2010","journal-title":"J. Mater. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"484","DOI":"10.1039\/C2TC00042C","article-title":"High dielectric constant rutile-polystyrene composite with enhanced percolative threshold","volume":"1","author":"Crippa","year":"2013","journal-title":"J. Mater. Chem. C"},{"key":"ref_7","first-page":"2089","article-title":"Preparation and dielectric properties of surface modified TiO2\/PEN composite films with high thermal stability and flexibility","volume":"23","author":"Huang","year":"2012","journal-title":"J. Mater. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"053711","DOI":"10.1063\/1.4864748","article-title":"Structural defects induced by Fe-ion implantation in TiO2","volume":"117","author":"Leedahl","year":"2014","journal-title":"J. Appl. Phys."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Raveau, B., and Motin Seikh, M.d. (2012). Cobalt Oxides: From Crystal Chemistry to Physics, Wiley\u2013VCH.","DOI":"10.1002\/9783527645527"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"166442","DOI":"10.1016\/j.jmmm.2020.166442","article-title":"Structural and magnetic properties of P25 TiO2 nanoparticles Nanoparticles Doped by Co","volume":"501","author":"Bessergenev","year":"2020","journal-title":"J. Magn. Magn. Mater."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1016\/S0167-5729(02)00100-0","article-title":"The surface science of titanium dioxide","volume":"48","author":"Diebold","year":"2003","journal-title":"Surf. Sci. Rep."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Astruc, D. (2008). Nanoparticles and Catalysis, Wiley\u2013VCH.","DOI":"10.1002\/9783527621323"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Carpenter, M.A., Mathus, S., and Kolmakov, A. (2013). Metal Oxide Nanomaterials for Chemical Sensors, Springer.","DOI":"10.1007\/978-1-4614-5395-6"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"219","DOI":"10.1016\/j.surfrep.2007.03.002","article-title":"Oxygen vacancies in transition metal and rare earth oxides: Current state of understanding and remaining challenges","volume":"62","author":"Hofmann","year":"2007","journal-title":"Surf. Sci. Rep."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.jphotochemrev.2015.08.003","article-title":"Visible-light activation of TiO2 photocatalysts: Advances in theory and experiments","volume":"25","author":"Etacheri","year":"2015","journal-title":"J. Photochem. Photobiol. C Photochem. Rev."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1722","DOI":"10.1016\/j.materresbull.2009.03.014","article-title":"High\u2013temperature anomalies of dielectric constant in TiO2 thin films","volume":"44","author":"Bessergenev","year":"2009","journal-title":"Mater. Res. Bull."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"855","DOI":"10.1007\/s10853-010-5113-0","article-title":"Review of the anatase to rutile phase transformation","volume":"46","author":"Hanaor","year":"2011","journal-title":"J. Mater. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"682","DOI":"10.1016\/j.apsusc.2016.06.178","article-title":"The effect of copper doping on photocatalytic activity of (101) planes of anatase TiO2: A theretical study","volume":"387","year":"2016","journal-title":"Appl. Surf. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"120380","DOI":"10.1016\/j.apcatb.2021.120380","article-title":"Insitu blue titania via band shape engineering for exceptional solar H2 production in rutile TiO2","volume":"297","author":"Esmail","year":"2021","journal-title":"Appl. Catal. B Environ."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"374","DOI":"10.1016\/j.jcrysgro.2007.03.021","article-title":"Synthesis, Raman and X-ray diffraction investigations of rubidium-doped Gd1.8Ti2O6.7 pyrochlore oxide via a sol\u2013gel process","volume":"304","author":"Garbout","year":"2007","journal-title":"J. Cryst. Growth"},{"key":"ref_21","unstructured":"Rodriguez-Carvajal, J. (2000). An Introduction to the Program FullProf 2000, Laboratorie L\u00e9on Brillouin (CEA\u2013CNRS)."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1107\/S0021889898009856","article-title":"Rietveld refinement guidelines","volume":"32","author":"McCusker","year":"1999","journal-title":"J. Appl. Crystallogr."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/j.apcata.2015.05.002","article-title":"An improvement of photocatalytic activity of TiO2 Degussa P25 powder","volume":"500","author":"Bessergenev","year":"2015","journal-title":"Appl. Catal. A Gen."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"274","DOI":"10.1016\/j.jallcom.2012.10.076","article-title":"Role of Co doping on structural, optical and magnetic properties of TiO2","volume":"552","author":"Kaushik","year":"2013","journal-title":"J. Alloys Compd."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1080\/00150198708016945","article-title":"Relaxor ferroelectrics","volume":"76","author":"Cross","year":"1987","journal-title":"Ferroelectrics"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1016\/S0920-5861(98)00050-9","article-title":"Surface area and pore texture of catalysts","volume":"41","author":"Leofanti","year":"1998","journal-title":"Catal. Today"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/S0927-7757(01)00612-4","article-title":"The use of nitrogen adsorption for the characterization of porous materials","volume":"187","author":"Sing","year":"2001","journal-title":"Colloids Surf. A Physicochem. Eng. Asp."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"045427","DOI":"10.1103\/PhysRevB.95.045427","article-title":"Competition of the coulomb and hopping-based exchange interactions in granular magnets","volume":"95","author":"Udalov","year":"2017","journal-title":"Phys. Rev. B"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"746","DOI":"10.1126\/science.1200448","article-title":"Increasing solar adsorption for photocatalysis with black Hydro-genated titanium dioxide nanocrystals","volume":"331","author":"Chen","year":"2011","journal-title":"Science"}],"container-title":["Nanomaterials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-4991\/11\/10\/2519\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:05:42Z","timestamp":1760166342000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-4991\/11\/10\/2519"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,9,27]]},"references-count":29,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2021,10]]}},"alternative-id":["nano11102519"],"URL":"https:\/\/doi.org\/10.3390\/nano11102519","relation":{},"ISSN":["2079-4991"],"issn-type":[{"value":"2079-4991","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,9,27]]}}}