{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T13:18:48Z","timestamp":1785417528836,"version":"3.56.0"},"reference-count":43,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T00:00:00Z","timestamp":1782864000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["22466010"],"award-info":[{"award-number":["22466010"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"award":["22466010"],"award-info":[{"award-number":["22466010"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Guizhou Provincial Basic Research Program (Natural Science) key program","award":["ZD [2025]075"],"award-info":[{"award-number":["ZD [2025]075"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nanomaterials"],"abstract":"<jats:p>Two-electron oxygen reduction reaction (2e\u2212-ORR) represents a sustainable and energy-efficient approach for decentralized hydrogen peroxide (H2O2) production compared with the conventional anthraquinone process. Among various electrocatalysts, metal\u2013nitrogen\u2013carbon (M\u2013N\u2013C) materials have attracted extensive attention owing to their tunable electronic structures and favorable *OOH adsorption behavior. However, the uncontrolled pyrolysis process generally leads to structurally heterogeneous and ill-defined coordination environments, making it difficult to precisely regulate active sites and understand catalytic mechanisms. Herein, we report a single-atom catalyst (CoN@OCNT) featuring spatially confined pyridinic-N-coordinated Co single sites, synthesized by anchoring a well-defined hexapod terpyridine Co-precursor onto oxidized carbon nanotubes (OCNTs) to suppress metal aggregation during pyrolysis. Benefiting from the optimized coordination environment and enhanced mass\/electron transfer, the CoN@OCNT catalyst exhibits nearly 100% H2O2 selectivity over a wide potential window from \u22121.0 to 0.66 V versus RHE in neutral electrolyte. In situ FT-IR and Raman spectroscopy reveal a rapid *OOH-mediated reaction pathway during the 2e\u2212-ORR process. Furthermore, membrane electrode assembly (MEA) testing demonstrates an H2O2 production rate of 21.8 mol h\u22121 gcat\u22121 with stable operation over 80 h at 60 mA cm\u22122. Remarkably, at an industrially relevant current density of 300 mA cm\u22122, the catalyst achieves a record H2O2 production rate of 70.3 mol h\u22121 gcat\u22121 and a salt-free H2O2 concentration of 9.4 mM, highlighting its great potential for practical large-scale H2O2 electrosynthesis in neutral media.<\/jats:p>","DOI":"10.3390\/nano16130813","type":"journal-article","created":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T12:41:38Z","timestamp":1782909698000},"page":"813","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Spatially Confined Co-N4 Sites on N-Doped Carbon Nanotube for Efficient Salt-Free Neutral H2O2 Electrosynthesis"],"prefix":"10.3390","volume":"16","author":[{"given":"Manman","family":"Zou","sequence":"first","affiliation":[{"name":"College of Materials & Metallurgy, Guizhou University, Huaxi District, Guiyang 550025, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoling","family":"Zhuang","sequence":"additional","affiliation":[{"name":"College of Materials & Metallurgy, Guizhou University, Huaxi District, Guiyang 550025, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qin","family":"Tian","sequence":"additional","affiliation":[{"name":"College of Materials & Metallurgy, Guizhou University, Huaxi District, Guiyang 550025, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0444-3744","authenticated-orcid":false,"given":"Jili","family":"Yuan","sequence":"additional","affiliation":[{"name":"College of Materials & Metallurgy, Guizhou University, Huaxi District, Guiyang 550025, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4668","DOI":"10.1007\/s12274-024-6505-9","article-title":"Selective oxygen electroreduction to hydrogen peroxide in acidic media: The superiority of single-atom catalysts","volume":"17","author":"Luo","year":"2024","journal-title":"Nano Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"108798","DOI":"10.1016\/j.nanoen.2023.108798","article-title":"Recent advances in single-atom catalysts for acidic electrochemical oxygen reduction to hydrogen peroxide","volume":"116","author":"Zhang","year":"2023","journal-title":"Nano Energy"},{"key":"ref_3","first-page":"122","article-title":"Strategies for Sustainable Production of Hydrogen Peroxide via Oxygen Reduction Reaction: From Catalyst Design to Device Setup","volume":"15","author":"Tian","year":"2023","journal-title":"Nanomicro Lett."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"9501","DOI":"10.1039\/D3GC02856A","article-title":"Review and perspectives on carbon-based electrocatalysts for the production of H2O2 via two-electron oxygen reduction","volume":"25","author":"He","year":"2023","journal-title":"Green Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"12372","DOI":"10.1021\/jacs.9b05576","article-title":"Activity-Selectivity Trends in the Electrochemical Production of Hydrogen Peroxide over Single-Site Metal-Nitrogen-Carbon Catalysts","volume":"141","author":"Sun","year":"2019","journal-title":"J. Am. Chem. Soc."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3997","DOI":"10.1038\/s41467-019-11992-2","article-title":"Highly selective oxygen reduction to hydrogen peroxide on transition metal single atom coordination","volume":"10","author":"Jiang","year":"2019","journal-title":"Nat. Commun."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"4064","DOI":"10.1021\/acscatal.8b00217","article-title":"Toward the Decentralized Electrochemical Production of H2O2: A Focus on the Catalysis","volume":"8","author":"Yang","year":"2018","journal-title":"ACS Catal."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"432","DOI":"10.1016\/j.jechem.2021.10.013","article-title":"Recent advances in electrocatalytic oxygen reduction for on-site hydrogen peroxide synthesis in acidic media","volume":"67","author":"Zhang","year":"2022","journal-title":"J. Energy Chem."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4225","DOI":"10.1038\/s41467-021-24329-9","article-title":"Highly active and selective oxygen reduction to H2O2 on boron-doped carbon for high production rates","volume":"12","author":"Xia","year":"2021","journal-title":"Nat. Commun."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e202306491","DOI":"10.1002\/anie.202306491","article-title":"Single-atom Iron Catalyst with Biomimetic Active Center to Accelerate Proton Spillover for Medical-level Electrosynthesis of H2O2 Disinfectant","volume":"62","author":"Li","year":"2023","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"106480","DOI":"10.1016\/j.nanoen.2021.106480","article-title":"A newly-explored Pd-based nanocrystal for the pH-universal electrosynthesis of H2O2","volume":"89","author":"Yang","year":"2021","journal-title":"Nano Energy"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"678","DOI":"10.1038\/s41467-024-44899-8","article-title":"Dithiine-linked metalphthalocyanine framework with undulated layers for highly efficient and stable H2O2 electroproduction","volume":"15","author":"Zhi","year":"2024","journal-title":"Nat. Commun."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"e202117347","DOI":"10.1002\/anie.202117347","article-title":"Engineering the Local Atomic Environments of Indium Single-Atom Catalysts for Efficient Electrochemical Production of Hydrogen Peroxide","volume":"61","author":"Zhang","year":"2022","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2106541","DOI":"10.1002\/adma.202106541","article-title":"Cation-Vacancy-Enriched Nickel Phosphide for Efficient Electrosynthesis of Hydrogen Peroxides","volume":"34","author":"Zhou","year":"2022","journal-title":"Adv. Mater."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"e202301879","DOI":"10.1002\/anie.202301879","article-title":"Atomic-Level Regulation of Cobalt Single-Atom Nanozymes: Engineering High-Efficiency Catalase Mimics","volume":"62","author":"Chen","year":"2023","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2003323","DOI":"10.1002\/aenm.202003323","article-title":"Electrocatalytic Oxygen Reduction to Hydrogen Peroxide: From Homogeneous to Heterogeneous Electrocatalysis","volume":"11","author":"Wang","year":"2020","journal-title":"Adv. Energy Mater."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1887","DOI":"10.1016\/j.joule.2023.06.022","article-title":"Interfacial electrochemical-chemical reaction coupling for efficient olefin oxidation to glycols","volume":"7","author":"Zhang","year":"2023","journal-title":"Joule"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2880","DOI":"10.1038\/s41467-022-30337-0","article-title":"Electrochemical oxygen reduction to hydrogen peroxide at practical rates in strong acidic media","volume":"13","author":"Zhang","year":"2022","journal-title":"Nat. Commun."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"14505","DOI":"10.1021\/jacs.2c01194","article-title":"Identification of the Highly Active Co\u2013N4 Coordination Motif for Selective Oxygen Reduction to Hydrogen Peroxide","volume":"144","author":"Chen","year":"2022","journal-title":"J. Am. Chem. Soc."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"122987","DOI":"10.1016\/j.apcatb.2023.122987","article-title":"Single atom catalysts for use in the selective production of hydrogen peroxide via two-electron oxygen reduction reaction: Mechanism, activity, and structure optimization","volume":"337","author":"Chen","year":"2023","journal-title":"Appl. Catal. B Environ."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"7819","DOI":"10.1021\/jacs.1c03135","article-title":"Tailoring acidic oxygen reduction selectivity on single-atom catalysts via modification of first and second coordination spheres","volume":"143","author":"Tang","year":"2021","journal-title":"J. Am. Chem. Soc."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"11042","DOI":"10.1021\/acscatal.9b02778","article-title":"Simultaneously Achieving High Activity and Selectivity toward Two-Electron O2 Electroreduction: The Power of Single-Atom Catalysts","volume":"9","author":"Guo","year":"2019","journal-title":"ACS Catal."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1675","DOI":"10.1038\/s41467-024-45990-w","article-title":"In situ modulating coordination fields of single-atom cobalt catalyst for enhanced oxygen reduction reaction","volume":"15","author":"Liu","year":"2024","journal-title":"Nat. Commun."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1801226","DOI":"10.1002\/aenm.201801226","article-title":"Atomically Dispersed Fe-Nx\/C Electrocatalyst Boosts Oxygen Catalysis via a New Metal-Organic Polymer Supramolecule Strategy","volume":"8","author":"Miao","year":"2018","journal-title":"Adv. Energy Mater."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"6285","DOI":"10.1021\/acs.chemmater.0c02010","article-title":"Comparing Methods for Quantifying Electrochemically Accumulated H2O2","volume":"32","author":"Gill","year":"2020","journal-title":"Chem. Mater."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"172","DOI":"10.1038\/s41467-023-35839-z","article-title":"Metal single-site catalyst design for electrocatalytic production of hydrogen peroxide at industrial-relevant currents","volume":"14","author":"Cao","year":"2023","journal-title":"Nat. Commun."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"4788","DOI":"10.1039\/D3TA06728A","article-title":"Highly selective hydrogen peroxide electrosynthesis on copper phthalocyanine: Interface engineering with an azo-polymer","volume":"12","author":"Sun","year":"2024","journal-title":"J. Mater. Chem. A"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2300895","DOI":"10.1002\/adfm.202300895","article-title":"Carbon Black-Supported Single-Atom Co-N-C as an Efficient Oxygen Reduction Electrocatalyst for H2O2 Production in Acidic Media and Microbial Fuel Cell in Neutral Media","volume":"33","author":"Du","year":"2023","journal-title":"Adv. Funct. Mater."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"121312","DOI":"10.1016\/j.apcatb.2022.121312","article-title":"Tuning the atomic configuration of Co-N-C electrocatalyst enables highly-selective H2O2 production in acidic media","volume":"310","author":"Liu","year":"2022","journal-title":"Appl. Catal. B Environ."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"142691","DOI":"10.1016\/j.cej.2023.142691","article-title":"Superior Efficiency Hydrogen Peroxide Production in Acidic Media through Epoxy Group Adjacent to Co-O\/C Active Centers on Carbon Black","volume":"465","author":"Yuan","year":"2023","journal-title":"Chem. Eng. J."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"658","DOI":"10.1016\/j.chempr.2019.12.008","article-title":"Enabling Direct H2O2 Production in Acidic Media through Rational Design of Transition Metal Single Atom Catalyst","volume":"6","author":"Gao","year":"2020","journal-title":"Chem"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2104718","DOI":"10.1002\/adma.202104718","article-title":"Atomically Dispersed Co2-N6 and Fe-N4 Costructures Boost Oxygen Reduction Reaction in Both Alkaline and Acidic Media","volume":"33","author":"Wang","year":"2021","journal-title":"Adv. Mater."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"3033","DOI":"10.1002\/anie.201912719","article-title":"Electrochemical Conversion of CO2 to Syngas with Controllable CO\/H2 Ratios over Co and Ni Single-Atom Catalysts","volume":"59","author":"He","year":"2020","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2314189","DOI":"10.1002\/adfm.202314189","article-title":"Cobalt Single-Atom Electrocatalysts Enhanced by Hydrogen-Bonded Organic Frameworks for Long-Lasting Zinc-Iodine Batteries","volume":"34","author":"Guo","year":"2024","journal-title":"Adv. Funct. Mater."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1164","DOI":"10.1038\/s41929-023-01047-7","article-title":"Co(CN)3 catalysts with well-defined coordination structure for the oxygen reduction reaction","volume":"6","author":"Sun","year":"2023","journal-title":"Nat. Catal."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"11104","DOI":"10.1039\/D1CP05631J","article-title":"Detailed formation process of Co@C catalysts and the influence of structural regulation on catalytic properties","volume":"24","author":"Cai","year":"2022","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"120904","DOI":"10.1016\/j.apcatb.2021.120904","article-title":"Dual optimization approach to Mo single atom dispersed g-C3N4 photocatalyst: Morphology and defect evolution","volume":"303","author":"Zhang","year":"2022","journal-title":"Appl. Catal. B Environ."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"e202304488","DOI":"10.1002\/ange.202304488","article-title":"p-Block Bismuth Nanoclusters Sites Activated by Atomically Dispersed Bismuth for Tandem Boosting Electrocatalytic Hydrogen Peroxide Production","volume":"135","author":"Zhu","year":"2023","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"26222","DOI":"10.1021\/jacs.3c08790","article-title":"Chemical Kinetic Method for Active-Site Quantification in Fe-N-C Catalysts and Correlation with Molecular Probe and Spectroscopic Site-Counting Methods","volume":"145","author":"Bates","year":"2023","journal-title":"J. Am. Chem. Soc."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"12855","DOI":"10.1002\/anie.201804978","article-title":"Adsorbed Intermediates in Oxygen Reduction on Platinum Nanoparticles Observed by In Situ IR Spectroscopy","volume":"57","author":"Nayak","year":"2018","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"2110734","DOI":"10.1002\/adfm.202110734","article-title":"Synergistic Electronic and Pore Structure Modulation in Open Carbon Nanocages Enabling Efficient Electrocatalytic Production of H2O2 in Acidic Medium","volume":"32","author":"Wang","year":"2022","journal-title":"Adv. Funct. Mater."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"716","DOI":"10.1038\/s41929-022-00826-y","article-title":"Linear paired electrochemical valorization of glycerol enabled by the electro-Fenton process using a stable NiSe2 cathode","volume":"5","author":"Sheng","year":"2022","journal-title":"Nat. Catal."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"196","DOI":"10.1021\/acsenergylett.2c01945","article-title":"Metal-Compound-Based Electrocatalysts for Hydrogen Peroxide Electrosynthesis and the Electro-Fenton Process","volume":"8","author":"Sheng","year":"2022","journal-title":"ACS Energy Lett."}],"container-title":["Nanomaterials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-4991\/16\/13\/813\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,3]],"date-time":"2026-07-03T04:33:42Z","timestamp":1783053222000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-4991\/16\/13\/813"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,1]]},"references-count":43,"journal-issue":{"issue":"13","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["nano16130813"],"URL":"https:\/\/doi.org\/10.3390\/nano16130813","relation":{},"ISSN":["2079-4991"],"issn-type":[{"value":"2079-4991","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,1]]}}}