{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T10:05:20Z","timestamp":1776852320311,"version":"3.51.2"},"reference-count":50,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,2,14]],"date-time":"2021-02-14T00:00:00Z","timestamp":1613260800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100014188","name":"Ministry of Science and ICT, South Korea","doi-asserted-by":"publisher","award":["2016R1A2B4010031, 2020R1F1A1065132"],"award-info":[{"award-number":["2016R1A2B4010031, 2020R1F1A1065132"]}],"id":[{"id":"10.13039\/501100014188","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Ministry of Education","award":["2020R1A6A1A03040570"],"award-info":[{"award-number":["2020R1A6A1A03040570"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This article presents the development of a highly sensitive electrochemical heavy metal sensor based on hierarchical porous carbon electrodes with sponge-like edge structures. Micrometer-scale hierarchical nanoporous carbon electrodes were fabricated at a wafer-scale using cost-effective batch microfabrication technologies, including the carbon microelectromechanical systems technology and oxygen plasma etching. The sponge-like hierarchical porous structure and sub-micrometer edges of the nanoporous carbon electrodes facilitate fast electron transfer rate and large active sites, leading to the efficient formation of dense heavy metal alloy particles of small sizes during the preconcentration step. This enhanced the peak current response during the square wave anodic stripping voltammetry, enabling the detection of Cd(II) and Pb(II) at concentrations as low as 0.41 and 0.7 \u03bcg L\u22121, respectively, with high sensitivity per unit sensing area (Cd: 109.45 nA \u03bcg\u22121 L mm\u22122, Pb: 100.37 nA \u03bcg\u22121 L mm\u22122).<\/jats:p>","DOI":"10.3390\/s21041346","type":"journal-article","created":{"date-parts":[[2021,2,14]],"date-time":"2021-02-14T05:54:49Z","timestamp":1613282089000},"page":"1346","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Hierarchical Porous Carbon Electrodes with Sponge-Like Edge Structures for the Sensitive Electrochemical Detection of Heavy Metals"],"prefix":"10.3390","volume":"21","author":[{"given":"Jongmin","family":"Lee","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Soosung","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5660-7093","authenticated-orcid":false,"given":"Heungjoo","family":"Shin","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"3433","DOI":"10.1021\/cr100383r","article-title":"Recent trends in macro-, micro-, and nanomaterial-based tools and strategies for heavy-metal detection","volume":"111","author":"Aragay","year":"2011","journal-title":"Chem. Rev."},{"key":"ref_2","unstructured":"US Environmental Protection Agency (1989). Seminar Publication: Risk Assessment, Management and Communication of Drinking Water Contamination."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"539","DOI":"10.1016\/j.talanta.2016.03.081","article-title":"Synthesis and application of Fe3O4@ SiO2@ TiO2 for photocatalytic decomposition of organic matrix simultaneously with magnetic solid phase extraction of heavy metals prior to ICP-MS analysis","volume":"154","author":"Habila","year":"2016","journal-title":"Talanta"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1041","DOI":"10.1016\/S0039-9140(00)00468-9","article-title":"Determination of trace metal ions by AAS in natural water samples after preconcentration of pyrocatechol violet complexes on an activated carbon column","volume":"52","author":"Narin","year":"2000","journal-title":"Talanta"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.trac.2013.09.009","article-title":"Trace and ultratrace analysis of liquid samples by X-ray fluorescence spectrometry","volume":"53","author":"Zawisza","year":"2014","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"445","DOI":"10.1021\/ac051166r","article-title":"Pushing the limits of mercury sensors with gold nanorods","volume":"78","author":"Rex","year":"2006","journal-title":"Anal. Chem."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1507","DOI":"10.1016\/S0584-8547(98)00127-X","article-title":"A simple, low cost, multielement atomic absorption spectrometer with a tungsten coil atomizer","volume":"53","author":"Wagner","year":"1998","journal-title":"Spectrochim. Acta Part B"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1039\/a905906g","article-title":"Application of a low power\/reduced pressure helium ICP ionization source for mass spectrometric detection of organobromine compounds and derivatized organotin compounds","volume":"15","author":"Waggoner","year":"2000","journal-title":"J. Anal. At. Spectrom."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1325","DOI":"10.1016\/j.envpol.2018.09.087","article-title":"Rapid in situ determination of heavy metal concentrations in polluted water via portable XRF: Using Cu and Pb as example","volume":"243","author":"Zhou","year":"2018","journal-title":"Environ. Pollut."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"503","DOI":"10.1007\/s00604-015-1651-0","article-title":"Screen-printed electrodes for environmental monitoring of heavy metal ions: A review","volume":"183","author":"Barton","year":"2016","journal-title":"Microchim. Acta"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Braga, M.S., Jaimes, R.F., Borysow, W., Gomes, O.F., and Salcedo, W.J. (2017). Portable multispectral colorimeter for metallic ion detection and classification. Sensors, 17.","DOI":"10.20944\/preprints201706.0058.v1"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"212","DOI":"10.1016\/j.trac.2017.06.005","article-title":"Paper-based microfluidic analytical devices for colorimetric detection of toxic ions: A review","volume":"93","author":"Sriram","year":"2017","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"120231","DOI":"10.1016\/j.talanta.2019.120231","article-title":"In-situ detection of cadmium with aptamer functionalized gold nanoparticles based on smartphone-based colorimetric system","volume":"208","author":"Gan","year":"2020","journal-title":"Talanta"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1016\/j.aca.2011.06.016","article-title":"Highly selective in situ metal ion determination by hybrid electrochemical \u201cadsorption\u2013desorption\u201d and colorimetric methods","volume":"701","author":"Li","year":"2011","journal-title":"Anal. Chim. Acta"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"127809","DOI":"10.1016\/j.snb.2020.127809","article-title":"Fully integrated battery-free and flexible electrochemical tag for on-demand wireless in situ monitoring of heavy metals","volume":"310","author":"Xu","year":"2020","journal-title":"Sens. Actuators B Chem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"544","DOI":"10.1016\/j.snb.2012.03.005","article-title":"Determination of cadmium (II) by square wave anodic stripping voltammetry using bismuth\u2013antimony film electrode","volume":"166","author":"Yi","year":"2012","journal-title":"Sens. Actuators B Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"713","DOI":"10.1021\/sc400019a","article-title":"Nanostructured sensors for detection of heavy metals: A review","volume":"1","author":"Li","year":"2013","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1080\/10408340903011820","article-title":"Mercury electrodes\u2013possibilities and limitations in environmental electroanalysis","volume":"39","author":"Barek","year":"2009","journal-title":"Crit. Rev. Anal. Chem."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1016\/j.talanta.2008.06.012","article-title":"Application of thin-shielded mercury microelectrodes in anodic stripping voltammetry","volume":"77","author":"Daniele","year":"2008","journal-title":"Talanta"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1341","DOI":"10.1002\/elan.200403270","article-title":"Stripping analysis at bismuth electrodes: A review","volume":"17","author":"Wang","year":"2005","journal-title":"Electroanalysis"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1016\/j.snb.2008.04.005","article-title":"Environmentally friendly disposable sensors with microfabricated on-chip planar bismuth electrode for in situ heavy metal ions measurement","volume":"134","author":"Zou","year":"2008","journal-title":"Sens. Actuators B Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"607","DOI":"10.1016\/S1872-2040(13)60726-4","article-title":"Application of nanopore and porous materials for heavy metal ion detection","volume":"42","author":"Zhang","year":"2014","journal-title":"Chin. J. Anal. Chem."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1016\/j.nanoen.2017.05.065","article-title":"Shape-controlled bismuth nanoflakes as highly selective catalysts for electrochemical carbon dioxide reduction to formate","volume":"39","author":"Kim","year":"2017","journal-title":"Nano Energy"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"517","DOI":"10.1039\/C5CS00670H","article-title":"Highly efficient nonprecious metal catalysts towards oxygen reduction reaction based on three-dimensional porous carbon nanostructures","volume":"45","author":"Zhu","year":"2016","journal-title":"Chem. Soc. Rev."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"615","DOI":"10.1016\/j.apsusc.2018.12.050","article-title":"Unravelling the adsorption disparity mechanism of heavy-metal ions on the biomass-derived hierarchically porous carbon","volume":"471","author":"Sun","year":"2019","journal-title":"Appl. Surf. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"320","DOI":"10.1016\/j.psep.2018.08.012","article-title":"Hierarchically porous nitrogen-doped carbon materials as efficient adsorbents for removal of heavy metal ions","volume":"119","author":"Yuan","year":"2018","journal-title":"Process. Saf. Environ. Prot."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"24622","DOI":"10.1021\/acsami.5b06698","article-title":"Oxygen-and nitrogen-enriched 3D porous carbon for supercapacitors of high volumetric capacity","volume":"7","author":"Li","year":"2015","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1007\/s12678-019-00568-9","article-title":"Kelp-Derived Activated Porous Carbon for the Detection of Heavy Metal Ions via Square Wave Anodic Stripping Voltammetry","volume":"11","author":"Guan","year":"2020","journal-title":"Electrocatalysis"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2181","DOI":"10.1016\/j.bios.2004.09.034","article-title":"From MEMS to NEMS with carbon","volume":"20","author":"Wang","year":"2005","journal-title":"Biosens. Bioelectron."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1016\/S0040-6090(01)01185-3","article-title":"Surface studies of carbon films from pyrolyzed photoresist","volume":"396","author":"Kostecki","year":"2001","journal-title":"Thin Solid Films"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Sharma, S. (2018). Glassy carbon: A promising material for micro-and nanomanufacturing. Materials, 11.","DOI":"10.3390\/ma11101857"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1002\/adfm.201402934","article-title":"Integration of 2D and 3D thin film glassy carbon electrode arrays for electrochemical dopamine sensing in flexible neuroelectronic implants","volume":"25","author":"VanDersarl","year":"2015","journal-title":"Adv. Funct. Mater."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Sharma, D., Lee, J., Seo, J., and Shin, H. (2017). Development of a Sensitive Electrochemical Enzymatic Reaction-Based Cholesterol Biosensor Using Nano-Sized Carbon Interdigitated Electrodes Decorated with Gold Nanoparticles. Sensors, 17.","DOI":"10.3390\/s17092128"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1149\/07201.0035ecst","article-title":"Pyrolytic carbon microelectrodes for impedance based cell sensing","volume":"72","author":"Caviglia","year":"2016","journal-title":"ECS Trans."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1016\/j.bios.2018.02.024","article-title":"All-carbon suspended nanowire sensors as a rapid highly-sensitive label-free chemiresistive biosensing platform","volume":"107","author":"Thiha","year":"2018","journal-title":"Biosens. Bioelectron."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"B132","DOI":"10.1149\/2.107308jes","article-title":"Optimization of Carbon Electrodes Derived from Epoxy-based Photoresist","volume":"160","author":"Mardegan","year":"2013","journal-title":"J. Electrochem. Soc."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"165301","DOI":"10.1088\/0957-4484\/25\/16\/165301","article-title":"Fabrication of polymer nanowires via maskless O2 plasma etching","volume":"25","author":"Du","year":"2014","journal-title":"Nanotechnology"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"A1886","DOI":"10.1149\/2.0561609jes","article-title":"Patternable nanoporous carbon electrodes for use as supercapacitors","volume":"163","author":"Lim","year":"2016","journal-title":"J. Electrochem. Soc."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"465","DOI":"10.1016\/j.jallcom.2017.01.098","article-title":"Increase in graphitization and electrical conductivity of glassy carbon nanowires by rapid thermal annealing","volume":"702","author":"Lim","year":"2017","journal-title":"J. Alloys Compd."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"11748","DOI":"10.1021\/la901072z","article-title":"Mechanisms of Oxygen Plasma Nanotexturing of Organic Polymer Surfaces: From Stable Super Hydrophilic to Super Hydrophobic Surfaces","volume":"25","author":"Tsougeni","year":"2009","journal-title":"Langmuir"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"6824","DOI":"10.1039\/C5TA09322H","article-title":"Laser induced MoS 2\/carbon hybrids for hydrogen evolution reaction catalysts","volume":"4","author":"Deng","year":"2016","journal-title":"J. Mater. Chem. A"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"4442","DOI":"10.20964\/2016.06.71","article-title":"Electrochemical methods of real surface area determination of noble metal electrodes\u2014An overview","volume":"11","author":"Soszko","year":"2016","journal-title":"Int. J. Electrochem. Sci."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"2029","DOI":"10.1016\/j.electacta.2009.11.026","article-title":"Structural and electrochemical features of 3D nanoporous platinum electrodes","volume":"55","author":"Park","year":"2010","journal-title":"Electrochim. Acta"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"524","DOI":"10.1088\/0960-1317\/17\/3\/015","article-title":"Stability of the hydrophilic behavior of oxygen plasma activated SU-8","volume":"17","author":"Walther","year":"2007","journal-title":"J. Micromech. Microeng."},{"key":"ref_45","unstructured":"Stone, D., and Ellis, J. (2003). Calibration and Linear Regression Analysis: A Self-Guided Tutorial. CHM314 Instrumental Analysis, Department of Chemistry, University of Toronto."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1016\/j.jelechem.2017.01.064","article-title":"Terephthalic acid capped iron oxide nanoparticles for sensitive electrochemical detection of heavy metal ions in water","volume":"788","author":"Deshmukh","year":"2017","journal-title":"J. Electroanal. Chem."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1016\/j.snb.2018.05.067","article-title":"The crystal facet-dependent electrochemical performance of TiO2 nanocrystals for heavy metal detection: Theoretical prediction and experimental proof","volume":"271","author":"Liao","year":"2018","journal-title":"Sens. Actuators B Chem."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1220","DOI":"10.1016\/j.snb.2017.08.046","article-title":"A miniaturized and flexible cadmium and lead ion detection sensor based on micro-patterned reduced graphene oxide\/carbon nanotube\/bismuth composite electrodes","volume":"255","author":"Xuan","year":"2018","journal-title":"Sens. Actuators B Chem."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1016\/j.foodchem.2018.08.110","article-title":"Simultaneous determination of Cd (II) and Pb (II) ions in honey and milk samples using a single-walled carbon nanohorns modified screen-printed electrochemical sensor","volume":"274","author":"Yao","year":"2019","journal-title":"Food Chem."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"127286","DOI":"10.1016\/j.snb.2019.127286","article-title":"Sensitive and selective detection of Pb (II) and Cu (II) using a metal-organic framework\/polypyrrole nanocomposite functionalized electrode","volume":"304","author":"Wang","year":"2020","journal-title":"Sens. Actuators B Chem."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/4\/1346\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:24:00Z","timestamp":1760160240000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/4\/1346"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,2,14]]},"references-count":50,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2021,2]]}},"alternative-id":["s21041346"],"URL":"https:\/\/doi.org\/10.3390\/s21041346","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,2,14]]}}}