{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:00:55Z","timestamp":1760144455226,"version":"build-2065373602"},"reference-count":48,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2024,4,24]],"date-time":"2024-04-24T00:00:00Z","timestamp":1713916800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Nanoporous (NP) gold, the most extensively studied and efficient NP metal, possesses exceptional properties that make it highly attractive for advanced technological applications. Notably, its remarkable catalytic properties in various significant reactions hold enormous potential. However, the exploration of its catalytic activity in the degradation of water pollutants remains limited. Nevertheless, previous research has reported the catalytic activity of NP Au in the degradation of methyl orange (MO), a toxic azo dye commonly found in water. This study aims to investigate the behavior of nanoporous gold in MO solutions using UV-Vis absorption spectroscopy and high-performance liquid chromatography. The NP Au was prepared by chemical removal of silver atoms of an AuAg precursor alloy prepared by ball milling. Immersion tests were conducted on both pellets and powders of NP Au, followed by examination of the residual solutions. Additionally, X-ray photoelectron spectroscopy and electrochemical impedance measurements were employed to analyze NP Au after the tests. The findings reveal that the predominant and faster process involves the partially reversible adsorption of MO onto NP Au, while the catalytic degradation of the dye plays a secondary and slower role in this system.<\/jats:p>","DOI":"10.3390\/molecules29091950","type":"journal-article","created":{"date-parts":[[2024,4,24]],"date-time":"2024-04-24T10:18:36Z","timestamp":1713953916000},"page":"1950","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Nanoporous Au Behavior in Methyl Orange Solutions"],"prefix":"10.3390","volume":"29","author":[{"given":"Andrea","family":"Pinna","sequence":"first","affiliation":[{"name":"Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Via Marengo 2, 09123 Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9101-0367","authenticated-orcid":false,"given":"Giorgio","family":"Pia","sequence":"additional","affiliation":[{"name":"Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Via Marengo 2, 09123 Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5839-8101","authenticated-orcid":false,"given":"Nicola","family":"Melis","sequence":"additional","affiliation":[{"name":"Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Via Marengo 2, 09123 Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2188-8059","authenticated-orcid":false,"given":"Mirko","family":"Prato","sequence":"additional","affiliation":[{"name":"Materials Characterization Facility, Italian Institute of Technology, Via Morego 30, 16163 Genoa, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9354-512X","authenticated-orcid":false,"given":"Maria Giorgia","family":"Cutrufello","sequence":"additional","affiliation":[{"name":"Department of Chemical and Geological Sciences, University of Cagliari, S.P. Monserrato-Sestu Km 0.700, 09042 Cagliari, Italy"},{"name":"National Interuniversity Consortium of Materials Science and Technology (INSTM), Via Giuseppe Giusti 9, 50121 Firenze, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2097-4358","authenticated-orcid":false,"given":"Elisa","family":"Sogne","sequence":"additional","affiliation":[{"name":"PoliFAB, Polytechnic of Milan, Via Giuseppe Colombo, 81, 20133 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andrea","family":"Falqui","sequence":"additional","affiliation":[{"name":"Department of Physics \u201cAldo Pontremoli\u201d, University of Milan, Via Celoria 16, 20133 Milan, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8753-7094","authenticated-orcid":false,"given":"Luca","family":"Pilia","sequence":"additional","affiliation":[{"name":"Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, Via Marengo 2, 09123 Cagliari, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,4,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"7016","DOI":"10.1039\/c2cs35210a","article-title":"Nanoporous Metals: Fabrication Strategies and Advanced Electrochemical Applications in Catalysis, Sensing and Energy Systems","volume":"41","author":"Zhang","year":"2012","journal-title":"Chem. Soc. Rev."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Pinna, A., Pia, G., Casula, M.F., Delogu, F., Sogne, E., Falqui, A., and Pilia, L. (2021). Fabrication of Nanoporous Al by Vapor-Phase Dealloying: Morphology Features, Mechanical Properties and Model Predictions. Appl. Sci., 11.","DOI":"10.3390\/app11146639"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1665","DOI":"10.3390\/met5031665","article-title":"Mechanical Properties of Nanoporous Au: From Empirical Evidence to Phenomenological Modeling","volume":"5","author":"Pia","year":"2015","journal-title":"Metals"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2188","DOI":"10.3390\/ma2042188","article-title":"Nanoporous Gold: Fabrication, Characterization, and Applications","volume":"2","author":"Seker","year":"2009","journal-title":"Materials"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"569","DOI":"10.1557\/mrs2009.156","article-title":"Nanoporous Metals for Catalytic and Optical Applications","volume":"34","author":"Ding","year":"2009","journal-title":"MRS Bull."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1700389","DOI":"10.1002\/adem.201700389","article-title":"Nanoporous Metals with Structural Hierarchy: A Review","volume":"19","author":"Juarez","year":"2017","journal-title":"Adv. Eng. Mater."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1146\/annurev-matsci-070115-031739","article-title":"Dealloying and Dealloyed Materials","volume":"46","author":"McCue","year":"2016","journal-title":"Annu. Rev. Mater. Res."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"e202200645","DOI":"10.1002\/cphc.202200645","article-title":"Nanoporous Au Formation on Au Substrates via High Voltage Electrolysis","volume":"24","author":"Artmann","year":"2023","journal-title":"ChemPhysChem"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.spmi.2017.01.011","article-title":"Nanoporous Au Structures by Dealloying Au\/Ag Thermal- or Laser-Dewetted Bilayers on Surfaces","volume":"103","author":"Ruffino","year":"2017","journal-title":"Superlattices Microstruct."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"6716","DOI":"10.1021\/acs.chemrev.2c00751","article-title":"Nanoporous Gold: From Structure Evolution to Functional Properties in Catalysis and Electrochemistry","volume":"123","author":"Wittstock","year":"2023","journal-title":"Chem. Rev."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1102","DOI":"10.1038\/nmat3741","article-title":"Spontaneous Evolution of Bicontinuous Nanostructures in Dealloyed Li-Based Systems","volume":"12","author":"Chen","year":"2013","journal-title":"Nat. Mater."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"5686","DOI":"10.1039\/C6NR09635B","article-title":"Evolution of Dealloying Induced Strain in Nanoporous Gold Crystals","volume":"9","author":"Harder","year":"2017","journal-title":"Nanoscale"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"043122","DOI":"10.1063\/1.3285175","article-title":"Morphological and Topological Analysis of Coarsened Nanoporous Gold by X-Ray Nanotomography","volume":"96","author":"Chen","year":"2010","journal-title":"Appl. Phys. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/j.actamat.2015.07.074","article-title":"Coarsening of Nanoporous Au: Relationship between Structure and Mechanical Properties","volume":"99","author":"Pia","year":"2015","journal-title":"Acta Mater."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1016\/j.actamat.2014.11.040","article-title":"Nanoporous Au: Statistical Analysis of Morphological Features and Evaluation of Their Influence on the Elastic Deformation Behavior by Phenomenological Modeling","volume":"85","author":"Pia","year":"2015","journal-title":"Acta Mater."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"115256","DOI":"10.1016\/j.scriptamat.2022.115256","article-title":"Evolution of Morphology and Microstructure of Coarsened Nanoporous Gold Studied by Automatic Thresholding and Image Recognition Algorithms","volume":"226","author":"Gao","year":"2023","journal-title":"Scr. Mater."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Satta, J., Pinna, A., Pia, G., Pilia, L., Carbonaro, C.M., Chiriu, D., Stagi, L., Abdullah, Q.A., and Ricci, P.C. (2022). Stable CsPbBr3 Nanocrystals\u2014Decorated Nanoporous Gold for Optoelectronic Applications. Crystals, 12.","DOI":"10.3390\/cryst12060863"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"037532","DOI":"10.1149\/1945-7111\/ab64c0","article-title":"Review\u2014Recent Advances in the Development of Nanoporous Au for Sensing Applications","volume":"167","author":"Chen","year":"2020","journal-title":"J. Electrochem. Soc."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"810","DOI":"10.1016\/j.cap.2018.03.021","article-title":"Nanoporous Gold: Preparation and Applications to Catalysis and Sensors","volume":"18","author":"Kim","year":"2018","journal-title":"Curr. Appl. Phys."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"319","DOI":"10.1126\/science.1183591","article-title":"Nanoporous Gold Catalysts for Selective Gas-Phase Oxidative Coupling of Methanol at Low Temperature","volume":"327","author":"Wittstock","year":"2010","journal-title":"Science"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"8845","DOI":"10.1002\/chem.202000471","article-title":"Nanoporous Metals for Heterogeneous Catalysis: Following the Success of Raney Nickel","volume":"26","author":"Gao","year":"2020","journal-title":"Chem.\u2014A Eur. J."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"8241","DOI":"10.1002\/anie.200602484","article-title":"Gold Catalysts: Nanoporous Gold Foams","volume":"45","author":"Zielasek","year":"2006","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1021\/ja0675503","article-title":"Low Temperature CO Oxidation over Unsupported Nanoporous Gold","volume":"129","author":"Xu","year":"2007","journal-title":"J. Am. Chem. Soc."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1007\/s10562-007-9344-x","article-title":"CO Oxidation Over a Fine Porous Gold Catalyst Fabricated by Selective Leaching from an Ordered AuCu3 Intermetallic Compound","volume":"121","author":"Kameoka","year":"2008","journal-title":"Catal. Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"5593","DOI":"10.1021\/jp808185v","article-title":"Nanoporous Au: An Unsupported Pure Gold Catalyst?","volume":"113","author":"Wittstock","year":"2009","journal-title":"J. Phys. Chem. C"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"279","DOI":"10.1016\/j.jcat.2019.06.016","article-title":"Design of Catalytically Active Porous Gold Structures from a Bottom-up Method: The Role of Metal Traces in CO Oxidation and Oxidative Coupling of Methanol","volume":"375","author":"Demirci","year":"2019","journal-title":"J. Catal."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"4066","DOI":"10.1002\/anie.200500382","article-title":"A Collaborative Effect between Gold and a Support Induces the Selective Oxidation of Alcohols","volume":"44","author":"Abad","year":"2005","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"332","DOI":"10.1016\/j.jcat.2007.08.004","article-title":"Aerobic Oxidation of Aqueous Ethanol Using Heterogeneous Gold Catalysts: Efficient Routes to Acetic Acid and Ethyl Acetate","volume":"251","author":"Christensen","year":"2007","journal-title":"J. Catal."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1132","DOI":"10.1038\/nature04190","article-title":"Tunable Gold Catalysts for Selective Hydrocarbon Oxidation under Mild Conditions","volume":"437","author":"Hughes","year":"2005","journal-title":"Nature"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"7154","DOI":"10.1002\/anie.200701622","article-title":"Gold Catalysts: Towards Sustainable Chemistry","volume":"46","author":"Ishida","year":"2007","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1039\/c1fd00022e","article-title":"Nanoporous Gold: A New Gold Catalyst with Tunable Properties","volume":"152","author":"Wittstock","year":"2011","journal-title":"Faraday Discuss."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1814","DOI":"10.1039\/c2cy20218b","article-title":"Catalytic Decoloration of Methyl Orange Solution by Nanoporous Metals","volume":"2","author":"Hakamada","year":"2012","journal-title":"Catal. Sci. Technol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"5291","DOI":"10.1002\/anie.200385122","article-title":"Color Chemistry. Synthesis, Properties and Applications of Organic Dyes and Pigments. 3rd Revised Edition. By Heinrich Zollinger","volume":"43","author":"Langhals","year":"2004","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"A141","DOI":"10.1016\/j.matpr.2021.01.258","article-title":"A Review on the Water Problem Associate with Organic Pollutants Derived from Phenol, Methyl Orange, and Remazol Brilliant Blue Dyes","volume":"31","author":"Sapawe","year":"2020","journal-title":"Mater. Today Proc."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1217","DOI":"10.1038\/s41598-023-50368-x","article-title":"Magnetic Fe3O4@SiO2 Study on Adsorption of Methyl Orange on Nanoparticles","volume":"14","author":"Li","year":"2024","journal-title":"Sci. Rep."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1038\/s41467-024-44699-0","article-title":"Overcoming the Permeability-Selectivity Challenge in Water Purification Using Two-Dimensional Cobalt-Functionalized Vermiculite Membrane","volume":"15","author":"Tian","year":"2024","journal-title":"Nat. Commun."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1016\/j.jcis.2019.03.107","article-title":"Acid-Salt Treated CoAl Layered Double Hydroxide Nanosheets with Enhanced Adsorption Capacity of Methyl Orange Dye","volume":"548","author":"Chen","year":"2019","journal-title":"J. Colloid. Interface Sci."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"127454","DOI":"10.1016\/j.jhazmat.2021.127454","article-title":"Magnesium\/Aluminum Layered Double Hydroxides Intercalated with Starch for Effective Adsorptive Removal of Anionic Dyes","volume":"424","author":"Grover","year":"2022","journal-title":"J. Hazard. Mater."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"100179","DOI":"10.1016\/j.crgsc.2021.100179","article-title":"Adsorption of Methyl Orange: A Review on Adsorbent Performance","volume":"4","author":"Iwuozor","year":"2021","journal-title":"Curr. Res. Green. Sustain. Chem."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"125938","DOI":"10.1016\/j.chemosphere.2020.125938","article-title":"Experimental Study on the Optimisation of Azo-Dyes Removal by Photo-Electrochemical Oxidation with TiO2 Nanotubes","volume":"248","author":"Mais","year":"2020","journal-title":"Chemosphere"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"4340","DOI":"10.1021\/jp811014u","article-title":"Photocatalysis in Gold Nanocage Nanoreactors","volume":"113","author":"Yen","year":"2009","journal-title":"J. Phys. Chem. A"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1016\/S0021-9517(03)00241-0","article-title":"Characterization and Photocatalytic Activity of Au\/TiO2 Thin Films for Azo-Dye Degradation","volume":"220","author":"Arabatzis","year":"2003","journal-title":"J. Catal."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1021\/cr00033a004","article-title":"Environmental Applications of Semiconductor Photocatalysis","volume":"95","author":"Hoffmann","year":"1995","journal-title":"Chem. Rev."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"247","DOI":"10.1016\/S1387-3806(01)00590-5","article-title":"Characterization of Methyl Orange and Its Photocatalytic Degradation Products by HPLC\/UV-VIS Diode Array and Atmospheric Pressure Ionization Quadrupole Ion","volume":"214","author":"Baiocchi","year":"2002","journal-title":"Int. J. Mass Spectrom."},{"key":"ref_45","unstructured":"Barbosa, J. (2005). Encyclopedia of Analytical Science, Elsevier."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"127279","DOI":"10.1016\/j.chemosphere.2020.127279","article-title":"Adsorption Isotherm Models: Classification, Physical Meaning, Application and Solving Method","volume":"258","author":"Wang","year":"2020","journal-title":"Chemosphere"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"K97","DOI":"10.1149\/2.097204jes","article-title":"Electrochemical Characterization of the Surface Area of Nanoporous Gold Films","volume":"159","author":"Rouya","year":"2012","journal-title":"J. Electrochem. Soc."},{"key":"ref_48","unstructured":"(2000). NIST X-ray Photoelectron Spectroscopy Database, NIST Standard Reference Database Number 20, National Institute of Standards and Technology."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/29\/9\/1950\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T14:33:30Z","timestamp":1760106810000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/29\/9\/1950"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,4,24]]},"references-count":48,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2024,5]]}},"alternative-id":["molecules29091950"],"URL":"https:\/\/doi.org\/10.3390\/molecules29091950","relation":{},"ISSN":["1420-3049"],"issn-type":[{"type":"electronic","value":"1420-3049"}],"subject":[],"published":{"date-parts":[[2024,4,24]]}}}