{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,3]],"date-time":"2026-04-03T06:36:43Z","timestamp":1775198203976,"version":"3.50.1"},"reference-count":65,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2022,7,19]],"date-time":"2022-07-19T00:00:00Z","timestamp":1658188800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"U.S. Naval Research Laboratory (NRL)"},{"name":"Office of Naval Research"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The electrochemical detection of heavy metal ions is reported using an inexpensive portable in-house built potentiostat and epitaxial graphene. Monolayer, hydrogen-intercalated quasi-freestanding bilayer, and multilayer epitaxial graphene were each tested as working electrodes before and after modification with an oxygen plasma etch to introduce oxygen chemical groups to the surface. The graphene samples were characterized using X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy, and van der Pauw Hall measurements. Dose\u2013response curves in seawater were evaluated with added trace levels of four heavy metal salts (CdCl2, CuSO4, HgCl2, and PbCl2), along with detection algorithms based on machine learning and library development for each form of graphene and its oxygen plasma modification. Oxygen plasma-modified, hydrogen-intercalated quasi-freestanding bilayer epitaxial graphene was found to perform best for correctly identifying heavy metals in seawater.<\/jats:p>","DOI":"10.3390\/s22145367","type":"journal-article","created":{"date-parts":[[2022,7,19]],"date-time":"2022-07-19T05:37:53Z","timestamp":1658209073000},"page":"5367","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["Modifications of Epitaxial Graphene on SiC for the Electrochemical Detection and Identification of Heavy Metal Salts in Seawater"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2227-4868","authenticated-orcid":false,"given":"Jenifer R.","family":"Hajzus","sequence":"first","affiliation":[{"name":"American Society for Engineering Education, U.S. Naval Research Laboratory, Washington, DC 20375, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9894-6640","authenticated-orcid":false,"given":"Lisa C.","family":"Shriver-Lake","sequence":"additional","affiliation":[{"name":"U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3394-6164","authenticated-orcid":false,"given":"Scott N.","family":"Dean","sequence":"additional","affiliation":[{"name":"U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0462-9872","authenticated-orcid":false,"given":"Jeffrey S.","family":"Erickson","sequence":"additional","affiliation":[{"name":"U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daniel","family":"Zabetakis","sequence":"additional","affiliation":[{"name":"U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joel","family":"Golden","sequence":"additional","affiliation":[{"name":"U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0797-5076","authenticated-orcid":false,"given":"Daniel J.","family":"Pennachio","sequence":"additional","affiliation":[{"name":"National Research Council, U.S. Naval Research Laboratory, Washington, DC 20375, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rachael L.","family":"Myers-Ward","sequence":"additional","affiliation":[{"name":"U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7996-590X","authenticated-orcid":false,"given":"Scott A.","family":"Trammell","sequence":"additional","affiliation":[{"name":"U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,7,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"697","DOI":"10.5194\/os-5-697-2009","article-title":"Electrochemical Techniques and Sensors for Ocean Research","volume":"5","author":"Denuault","year":"2009","journal-title":"Ocean Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1108\/02602281211197116","article-title":"A Review of in Situ Methods and Sensors for Monitoring the Marine Environment","volume":"32","author":"Mills","year":"2012","journal-title":"Sens. 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