{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,4]],"date-time":"2026-11-04T03:32:49Z","timestamp":1793763169937,"version":"4.6.1"},"reference-count":43,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2025,12,31]],"date-time":"2025-12-31T00:00:00Z","timestamp":1767139200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003562","name":"Ministry of Environment","doi-asserted-by":"publisher","award":["RT2025010107"],"award-info":[{"award-number":["RT2025010107"]}],"id":[{"id":"10.13039\/501100003562","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Nitrogen oxides (NOx) emitted mainly from vehicle exhaust significantly contribute to urban air pollution, leading to photochemical smog and secondary particulate matter. Photocatalytic technology has emerged as a promising solution for continuous NOx decomposition under ultraviolet (UV) irradiation. This study developed an eco-friendly permeable concrete incorporating activated loess and zeolite to improve roadside air quality. The high porosity and adsorption capability of the concrete provided a suitable substrate for a TiO2-based photocatalytic coating. A single-component coating system was optimized by introducing colloidal silica to enhance TiO2 particle dispersibility and adding a binder to secure durable adhesion on the concrete surface. The produced permeable concrete met sidewalk quality standards specified in SPS-F-KSPIC-001-2006. Photocatalytic NOx removal performance evaluated by ISO 22197-1 showed a maximum removal efficiency of 77.5%. Even after 300 h of accelerated weathering, the activity loss remained within 13.8%, retaining approximately 80% of the initial performance. Additionally, outdoor mock-up testing under natural light confirmed NOx concentration removal and formation of nitrate by-products, demonstrating practical applicability in real environments. Overall, the integration of permeable concrete and a durable, single-component TiO2 photocatalytic coating provides a promising approach to simultaneously enhance pavement sustainability and reduce urban NOx pollution.<\/jats:p>","DOI":"10.3390\/ma19010148","type":"journal-article","created":{"date-parts":[[2025,12,31]],"date-time":"2025-12-31T16:08:00Z","timestamp":1767197280000},"page":"148","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Photocatalytic NOx Removal Performance of TiO2-Coated Permeable Concrete: Laboratory Optimization and Field Demonstration"],"prefix":"10.3390","volume":"19","author":[{"given":"Han-Na","family":"Kim","sequence":"first","affiliation":[{"name":"Carbon-Neutral Road Construction Technology Research Institute, 62, Cheongsu 14-ro, Dongnam-gu, Cheonan-si 31198, Chungcheongnam-do, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyeok-Jung","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Architecture Engineering and Civil Engineering, Hoseo University, 20, Hoseo-ro 79beon-gil, Baebang-eup, Asan-si 31499, Chungcheongnam-do, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e13484","DOI":"10.1002\/ep.13484","article-title":"Nitrogen Oxides and Ozone in Urban Air: A Review of 50 plus Years of Progress","volume":"39","author":"Erickson","year":"2020","journal-title":"Environ. Prog. Sustain. Energy"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Jia, C., Yan, G., Yu, X., Li, X., Xue, J., Wang, Y., and Cao, Z. (2025). Evidence for Coordinated Control of PM2.5 and O3: Long-Term Observational Study in a Typical City of Central Plains Urban Agglomeration. Toxics, 13.","DOI":"10.3390\/toxics13050330"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"He, J., Wang, T., Li, H., Zhou, Y., Liu, Y., and Xu, A. (2025). Synergistic Toxicity of Fine Particulate Matter and Ozone and Their Underlying Mechanisms. Toxics, 13.","DOI":"10.3390\/toxics13040236"},{"key":"ref_4","first-page":"100771","article-title":"Comprehensive Review of Health Impacts of the Exposure to Nitrogen Oxides (NOx), Carbon Dioxide (CO2), and Particulate Matter (PM)","volume":"19","author":"Taha","year":"2025","journal-title":"J. Hazard. Mater. Adv."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1730","DOI":"10.1038\/s41467-025-56963-y","article-title":"Associations of Long-Term Exposure to Nitrogen Oxides with All-Cause and Cause-Specific Mortality","volume":"16","author":"Yang","year":"2025","journal-title":"Nat. Commun."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"47452","DOI":"10.1021\/acsomega.3c03751","article-title":"Study on Control Strategies on NOX Emissions to Meet Real Driving Emissions","volume":"8","author":"Chen","year":"2023","journal-title":"ACS Omega"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Wang, F., Zhao, J., Li, T., Guan, P., Liu, S., Wei, H., and Zhou, L. (2025). Research on NOx Emissions Testing and Optimization Strategies for Diesel Engines Under Low-Load Cycles. Atmosphere, 16.","DOI":"10.3390\/atmos16020190"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Ahn, H.R., Lee, S.W., Kim, J.H., and Kim, Y.K. (2023). Estimation of Nitrogen Oxides (NOx) Removal Efficiency for TiO2 Concrete. Sustainability, 15.","DOI":"10.3390\/su15119098"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"365","DOI":"10.1061\/(ASCE)MT.1943-5533.0000613","article-title":"Sustainable Photocatalytic Asphalt Pavements for Mitigation of Nitrogen Oxide and Sulfur Dioxide Vehicle Emissions","volume":"25","author":"Hassan","year":"2013","journal-title":"J. Mater. Civ. Eng."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Kim, H.J., and Hong, K. (2023). Evaluation of Nitrogen Oxide Reduction Performance in Permeable Concrete Surfaces Treated with a TiO2 Photocatalyst. Materials, 16.","DOI":"10.3390\/ma16165512"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Song, Y.W., Kim, M.Y., Chung, M.H., Yang, Y.K., and Park, J.C. (2020). NOx-Reduction Performance Test for TiO2 Paint. Molecules, 25.","DOI":"10.3390\/molecules25184087"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"134396","DOI":"10.1016\/j.jclepro.2022.134396","article-title":"NOx Removal Ability of Photocatalytic Cement-Based Materials with Porous Structure","volume":"377","author":"Zhang","year":"2022","journal-title":"J. Clean. Prod."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1016\/j.cemconres.2018.11.002","article-title":"Photocatalytic Concrete for NOx Abatement: Supported TiO2 Efficiencies and Impacts","volume":"116","author":"Yang","year":"2019","journal-title":"Cem. Concr. Res."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"123835","DOI":"10.1016\/j.conbuildmat.2021.123835","article-title":"Photocatalytic Concrete for NOx Degradation: Influence Factors and Durability","volume":"298","author":"Si","year":"2021","journal-title":"Constr. Build. Mater."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Hot, J., F\u00e9riot, C., Lenard, E., and Ringot, E. (2024). NOx Abatement by a TiO2-Based Coating under Real-Life Conditions and Laboratory-Scale Durability Assessment. Environments, 11.","DOI":"10.3390\/environments11080166"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Jia, Z., Zhao, Y., and Niu, H. (2024). Damage Evolution and NOx Photocatalytic Degradation Performance of Nano-TiO2 Concrete Under Freeze\u2013Thaw Cycles. Buildings, 14.","DOI":"10.3390\/buildings14123763"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Hamidi, F., and Aslani, F. (2019). TiO2-Based Photocatalytic Cementitious Composites: Materials, Properties, Influential Parameters, and Assessment Techniques. Nanomaterials, 9.","DOI":"10.3390\/nano9101444"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Oviedo, I., Pradena, M., Link, \u00d3., and Balbo, J.T. (2022). Using Natural Pozzolans to Partially Replace Cement in Pervious Concretes: A Sustainable Alternative?. Sustainability, 14.","DOI":"10.3390\/su142114122"},{"key":"ref_19","first-page":"307","article-title":"Durability and Mechanical Performance in Activated Hwangtoh-Based Composite for NOx Reduction","volume":"11","author":"Kim","year":"2021","journal-title":"Adv. Concr. Constr."},{"key":"ref_20","first-page":"e00274","article-title":"Stormwater Retention Using Pervious Concrete Pavement: Great Western Sydney Case Study","volume":"11","author":"Sartipi","year":"2019","journal-title":"Case Stud. Constr. Mater."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"100534","DOI":"10.1016\/j.uclim.2019.100534","article-title":"The Use of Permeable and Reflective Pavements as a Potential Strategy for Urban Heat Island Mitigation","volume":"31","author":"Ferrari","year":"2020","journal-title":"Urban Clim."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Singer, M.N., Hamouda, M.A., El-Hassan, H., and Hinge, G. (2022). Permeable Pavement Systems for Effective Management of Stormwater Quantity and Quality: A Bibliometric Analysis and Highlights of Recent Advancements. Sustainability, 14.","DOI":"10.3390\/su142013061"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Amani, M.J., Tanzadeh, R., Moghadas Nejad, F., Kabiri Nasrabad, M.M., Chalabii, J., and Movahedi Rad, M. (2025). Urban Sustainability Through Pavement Technologies: Reducing Urban Heat Islands with Cool Pavements. Buildings, 15.","DOI":"10.3390\/buildings15030504"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1186\/s40069-020-00404-1","article-title":"Influence of Pore Structure Characteristics on the Mechanical and Durability Behavior of Pervious Concrete Material Based on Image Analysis","volume":"14","author":"Liu","year":"2020","journal-title":"Int. J. Concr. Struct. Mater."},{"key":"ref_25","first-page":"e01606","article-title":"Study on Photocatalytic and Mechanical Properties of TiO2 Modified Pervious Concrete","volume":"17","author":"Wu","year":"2022","journal-title":"Case Stud. Constr. Mater."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"874","DOI":"10.1016\/j.conbuildmat.2012.04.097","article-title":"Pervious Concrete with Titanium Dioxide as a Photocatalyst Compound for a Greener Urban Road Environment","volume":"35","author":"Shen","year":"2012","journal-title":"Constr. Build. Mater."},{"key":"ref_27","unstructured":"(2017). Standard Specification for Coarse Aggregate for Porous Concrete (Standard No. KS F 2527)."},{"key":"ref_28","first-page":"405","article-title":"Evaluation of Mechanical Properties of Mortar Mixed with Zeolites and Active Hwangtoh","volume":"7","author":"Kwon","year":"2019","journal-title":"J. Korean Recycl. Constr. Resour. Inst."},{"key":"ref_29","unstructured":"(2025, December 28). AERODISP\u00ae W 740 X. Available online: https:\/\/www.evonik.com\/en\/products\/se\/pr_52009433.html."},{"key":"ref_30","unstructured":"(2006). Standard Specification for Permeable Concrete Pavement (Standard No. SPS-F-KSPIC-001-2006)."},{"key":"ref_31","unstructured":"(2010). Standard Test Method for Compressive Strength of Concrete (Standard No. KS F 2405)."},{"key":"ref_32","unstructured":"(2016). Standard Test Method for Flexural Strength of Concrete (Standard No. KS F 2408)."},{"key":"ref_33","unstructured":"(2010). Standard Test Method for Skid Resistance of Pavement Surface (Standard No. KS F 2375)."},{"key":"ref_34","unstructured":"(2010). Standard Test Method for Permeability of Concrete (Standard No. KS F 4001)."},{"key":"ref_35","unstructured":"(2013). Standard Test Method for Resistance of Concrete to Freezing and Thawing (Standard No. KS F 2456)."},{"key":"ref_36","unstructured":"(2016). Fine Ceramics (Advanced Ceramics, Advanced Technical Ceramics)\u2014Test Method for Air-Purification Performance of Semiconducting Photocatalytic Materials\u2014Part 1: Removal of Nitric Oxide (Standard No. ISO 22197-1:2016). Available online: https:\/\/www.iso.org\/standard\/65416.html."},{"key":"ref_37","unstructured":"(2013). Plastics\u2014Methods of Exposure to Laboratory Light Sources\u2014Part 2: Xenon-Arc Lamps (Standard No. KS M ISO 4892-2:2013)."},{"key":"ref_38","unstructured":"(1993). Textiles\u2014Tests for Colour Fastness\u2014Part A02: Grey Scale for Assessing Change in Colour (Standard No. KS M ISO 105-A02:1993)."},{"key":"ref_39","unstructured":"(2015). General Rules for the Description of Colour and Gloss (Standard No. KS A 0063:2015)."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"754","DOI":"10.1016\/j.dyepig.2007.01.020","article-title":"Control of the Photocatalytic Activity of TiO2 Nanoparticles by Silica Coating with Polydiethoxysiloxane","volume":"76","author":"Siddiquey","year":"2008","journal-title":"Dye. Pigment."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"194","DOI":"10.1016\/j.surfin.2018.10.005","article-title":"The Effect of SiO2 on TiO2-SiO2 Composite Film for Self-Cleaning Application","volume":"16","author":"Zhang","year":"2019","journal-title":"Surf. Interfaces"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/j.surfcoat.2004.02.022","article-title":"Relationship between Photocatalytic Activity, Hydrophilicity and Self-Cleaning Effect of TiO2\/SiO2 Films","volume":"191","author":"Guan","year":"2005","journal-title":"Surf. Coat. Technol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"2323","DOI":"10.1007\/s12633-024-02870-8","article-title":"A Critical Review of the Evaluation of SiO2-Incorporated TiO2 Nanocomposite for Photocatalytic Activity","volume":"16","author":"Tuama","year":"2024","journal-title":"Silicon"}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/1\/148\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,6]],"date-time":"2026-01-06T05:26:39Z","timestamp":1767677199000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/1\/148"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,31]]},"references-count":43,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["ma19010148"],"URL":"https:\/\/doi.org\/10.3390\/ma19010148","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,31]]}}}