{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T05:04:06Z","timestamp":1787029446881,"version":"build-2736575974"},"reference-count":56,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T00:00:00Z","timestamp":1784764800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>This study explores the energy-harvesting performance of aluminum (Al)- and iron (Fe)-filled styrene\u2013butadiene rubber (SBR) composites, with a focus on their mechanical durability and triboelectric properties. Comprehensive mechanical characterization\u2014including tensile strength, elongation at break, fracture toughness, and elasticity\u2014reveals that Fe-filled composites exhibit significantly enhanced reinforcement compared to Al-filled systems at equivalent filler loadings. Raman spectroscopy indicates that Fe atoms can coordinate with the benzene rings of SBR chains through stronger physicochemical bonding, a feature less present in Al-based composites. In addition to improved mechanical properties, Fe-filled composites demonstrate higher electrical conductivity and superior triboelectric energy-harvesting performance. Notably, the composite containing 15 vol% Fe under 1% cyclic compressive strain achieves a peak current density of 127.05 \u00b5A\/m2, a total generated charge of 5.01 nC, and a peak power density of 48.22 \u00b5W\/m2. These values represent substantial enhancements of 246%, 236%, and 2398%, respectively, compared to Al-filled counterparts. Cyclic energy-harvesting tests confirm stable performance with negligible degradation in output or mechanical integrity over repeated cycles. Rubber composite shows good humidity resistance in current and voltage outputs. Furthermore, a layer-by-layer triboelectric nanogenerator (TENG) based on the Fe-filled composite produces output signals of approximately \u00b11.0 \u00b5A and \u00b15 V under biomechanical hand patting. The superior performance of Fe-based composites is attributed to stronger filler\u2013rubber interactions, likely facilitated by electrostatic interactions, which enhances interfacial charge transfer during mechanical deformation. Overall, Fe-filled SBR composites demonstrate strong potential for cost-effective, environmentally friendly, and durable self-powered energy-harvesting applications.<\/jats:p>","DOI":"10.3390\/polym18151801","type":"journal-article","created":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T15:05:42Z","timestamp":1784819142000},"page":"1801","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Metallic (Al and Fe) Powder-Reinforced Styrene\u2013Butadiene Rubber Composites for Triboelectric Energy Harvesting"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7600-6183","authenticated-orcid":false,"given":"Md Najib","family":"Alam","sequence":"first","affiliation":[{"name":"School of Mechanical Engineering, Yeungnam University, 280 Daehak-ro, Gyeongsan 38541, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6658-0891","authenticated-orcid":false,"given":"Vishnu Shankar","family":"Dhandapani","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Yeungnam University, 280 Daehak-ro, Gyeongsan 38541, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1201-558X","authenticated-orcid":false,"given":"Sang-Shin","family":"Park","sequence":"additional","affiliation":[{"name":"School of Mechanical Engineering, Yeungnam University, 280 Daehak-ro, Gyeongsan 38541, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"101689","DOI":"10.1016\/j.isci.2020.101689","article-title":"Recent Progress in Hybridized Nanogenerators for Energy Scavenging","volume":"23","author":"Zhang","year":"2020","journal-title":"iScience"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"100990","DOI":"10.1016\/j.nanoso.2023.100990","article-title":"Recent Advances of Triboelectric, Piezoelectric and Pyroelectric Nanogenerators","volume":"35","author":"Dong","year":"2023","journal-title":"Nano-Struct. Nano-Objects"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"683","DOI":"10.1080\/14686996.2020.1800366","article-title":"Aim High Energy Conversion Efficiency in Triboelectric Nanogenerators","volume":"21","author":"Yoon","year":"2020","journal-title":"Sci. Technol. Adv. Mater."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"41657","DOI":"10.1021\/acsami.1c11212","article-title":"Suppressing Thermal Negative Effect and Maintaining High-Temperature Steady Electrical Performance of Triboelectric Nanogenerators by Employing Phase Change Material","volume":"13","author":"Cao","year":"2021","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"101723","DOI":"10.1016\/j.progpolymsci.2023.101723","article-title":"Polymer-Based Triboelectric Nanogenerators: Materials, Characterization, and Applications","volume":"144","author":"Shanbedi","year":"2023","journal-title":"Prog. Polym. Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"49600","DOI":"10.1039\/D5RA06645J","article-title":"Recent Trends and Future Perspectives of Triboelectric Nanogenerators (TENGs) and Applications","volume":"15","author":"Rajasekar","year":"2025","journal-title":"RSC Adv."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Choi, G.J., Sohn, S.H., Kim, S.J., and Park, I.K. (2025). Polymer Composite-Based Triboelectric Nanogenerators: Recent Progress, Design Principles, and Future Perspectives. Polymers, 17.","DOI":"10.3390\/polym17141962"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"30079","DOI":"10.1021\/acsami.6b08002","article-title":"Improving the Working Efficiency of a Triboelectric Nanogenerator by the Semimetallic PEDOT:PSS Hole Transport Layer and Its Application in Self-Powered Active Acetylene Gas Sensing","volume":"8","author":"Uddin","year":"2016","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Sutradhar, S.C., Banik, N., Khan, M.M.R., and Jeong, J.H. (2025). Polymer Gel-Based Triboelectric Nanogenerators: Conductivity and Morphology Engineering for Advanced Sensing Applications. Gels, 11.","DOI":"10.3390\/gels11090737"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2000186","DOI":"10.1002\/advs.202000186","article-title":"Polymer Materials for High-Performance Triboelectric Nanogenerators","volume":"7","author":"Chen","year":"2020","journal-title":"Adv. Sci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"925","DOI":"10.1016\/S0142-9418(01)00035-6","article-title":"Effect of High-Temperature Curing on the Crosslink Structures and Dynamic Mechanical Properties of Gum and N330-Filled Natural Rubber Vulcanizates","volume":"20","author":"Fan","year":"2001","journal-title":"Polym. Test."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"973","DOI":"10.1021\/acsami.2c17057","article-title":"Engineering Triboelectric Charge in Natural Rubber\u2013Ag Nanocomposite for Enhancing Electrical Output of a Triboelectric Nanogenerator","volume":"15","author":"Appamato","year":"2023","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Chomjun, T., Appamato, I., Harnchana, V., and Amornkitbamrung, V. (2022). Eco-Friendly Triboelectric Material Based on Natural Rubber and Activated Carbon from Human Hair. Polymers, 14.","DOI":"10.3390\/polym14061110"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1069","DOI":"10.1021\/acsaenm.3c00056","article-title":"All-Silicone Rubber Triboelectric Nanogenerators with Graphite-Impregnated Electrodes","volume":"1","author":"Candido","year":"2023","journal-title":"ACS Appl. Eng. Mater."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"155315","DOI":"10.1016\/j.cej.2024.155315","article-title":"Flexible, Wearable Triboelectric Rubber with Tunable Surface Charge Density Enabled by Regulation of Surface Functional Group Density and Permittivity","volume":"498","author":"Lu","year":"2024","journal-title":"Chem. Eng. J."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2425366","DOI":"10.1002\/adfm.202425366","article-title":"Special Rubber with Excellent Mechanical Strength, Environmental Stability, and Electrical Conductivity for Accordion-Structured High-Performance Triboelectric Nanogenerators","volume":"35","author":"Gao","year":"2025","journal-title":"Adv. Funct. Mater."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Alam, M.N., Kumar, V., Kim, Y., Lee, D.J., and Park, S.S. (2025). High-Performance Barium Titanate, Carbon Nanotube, and Styrene\u2013Butadiene Rubber-Based Single Composite TENG for Energy Harvesting and Handwriting Recognition. Polymers, 17.","DOI":"10.3390\/polym17152016"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"14491","DOI":"10.1002\/pc.30091","article-title":"Diatomaceous Earth and Carbon Nanotubes Toughened Advanced Rubber Composite for Triboelectric Nanogenerator and Sensor Applications","volume":"46","author":"Alam","year":"2025","journal-title":"Polym. Compos."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3688","DOI":"10.1002\/adfm.201500428","article-title":"Stretchable-Rubber-Based Triboelectric Nanogenerator and Its Application as Self-Powered Body Motion Sensors","volume":"25","author":"Yi","year":"2015","journal-title":"Adv. Funct. Mater."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"177114","DOI":"10.1016\/j.jallcom.2024.177114","article-title":"Boosting Triboelectric Performance of PDMS-Based Nanogenerators through Dual-Filler Embedded Triboelectric Layers","volume":"1010","author":"Lee","year":"2025","journal-title":"J. Alloys Compd."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"3111","DOI":"10.1002\/pol.20250405","article-title":"Enhanced Output Performance of Triboelectric Nanogenerator Incorporated with Poly(Vinylidene Fluoride)-Derived Carbon Dots","volume":"63","author":"Li","year":"2025","journal-title":"J. Polym. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"126244","DOI":"10.1016\/j.polymer.2023.126244","article-title":"A Novel Mechanism of Hybrid Fillers on Enhanced Dielectric Constant and Suppressed Dielectric Loss in Percolative Nanocomposites","volume":"283","author":"Zhang","year":"2023","journal-title":"Polymer"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2400127","DOI":"10.1002\/aesr.202400127","article-title":"Carbon-Based Textile-Structured Triboelectric Nanogenerators for Smart Wearables","volume":"5","author":"Sayam","year":"2024","journal-title":"Adv. Energy Sustain. Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"16905","DOI":"10.1039\/C4TA03732D","article-title":"Magnetic Carbon Nanofibers Containing Uniformly Dispersed Fe\/Co\/Ni Nanoparticles as Stable and High-Performance Electromagnetic Wave Absorbers","volume":"2","author":"Xiang","year":"2014","journal-title":"J. Mater. Chem. A"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1345","DOI":"10.1016\/j.compositesa.2010.07.003","article-title":"Dispersion and Functionalization of Carbon Nanotubes for Polymer-Based Nanocomposites: A Review","volume":"41","author":"Ma","year":"2010","journal-title":"Compos. Part A Appl. Sci. Manuf."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"117271","DOI":"10.1016\/j.synthmet.2022.117271","article-title":"Towards a Cost-Effective Carbon Nanofillers-Based Composites for EMI Shielding Applications","volume":"293","year":"2023","journal-title":"Synth. Met."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Alam, M.N., Azam, S., Yun, J., and Park, S.S. (2025). Critical Role of Rubber Functionalities on the Mechanical and Electrical Responses of Carbon Nanotube-Based Electroactive Rubber Composites. Polymers, 17.","DOI":"10.3390\/polym17020127"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Chenkhunthod, S., Yamklang, W., Kaeochana, W., Prada, T., Bunriw, W., and Harnchana, V. (2023). Ag\u2013Cellulose Hybrid Filler for Boosting the Power Output of a Triboelectric Nanogenerator. Polymers, 15.","DOI":"10.3390\/polym15051295"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1782","DOI":"10.1039\/D3TC03976E","article-title":"Enhancing PDMS-Based Triboelectric Nanogenerator Output by Optimizing the Microstructure and Dielectric Constant","volume":"12","author":"Zhu","year":"2024","journal-title":"J. Mater. Chem. C"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"113682","DOI":"10.1016\/j.materresbull.2025.113682","article-title":"TiO2\/Ag Hybrid Filler with Synergistic Effect of Dielectric Modulation and Photocharge Generation in the Natural Rubber-Based Triboelectric Nanogenerator","volume":"193","author":"Bunriw","year":"2025","journal-title":"Mater. Res. Bull."},{"key":"ref_31","first-page":"264","article-title":"A Theoretical Report on Electronic Polarizability of Metals","volume":"5","author":"Adesakin","year":"2023","journal-title":"NIPES J. Sci. Technol. Res."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"114158","DOI":"10.1016\/j.materresbull.2026.114158","article-title":"Synergistic Enhancement of Mechanical Properties and Energy Harvesting Performances in Styrene\u2013Butadiene Rubber-Based TENGs via Stearic Acid Modified BaTiO3 and Mo2 Hybrid Fillers","volume":"201","author":"Alam","year":"2026","journal-title":"Mater. Res. Bull."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"134786","DOI":"10.1016\/j.colsurfa.2024.134786","article-title":"Highly Conductive Rubber-Based Electrode with a Robust Wrinkled Mesh-Like Copper Coating for Stretchable Triboelectric Nanogenerator","volume":"700","author":"Bi","year":"2024","journal-title":"Colloids Surf. A Physicochem. Eng. Asp."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1543","DOI":"10.1007\/s40684-023-00517-4","article-title":"High Performance Triboelectric Nanogenerator Based on Ultrastretchable Composite Electrode","volume":"10","author":"Kim","year":"2023","journal-title":"Int. J. Precis. Eng. Manuf.-Green Technol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"14205","DOI":"10.1039\/D3NR02849F","article-title":"Highly Stretchable Hydroxyapatite Bionanocomposite for High-Performance Triboelectric Nanogenerators","volume":"15","author":"Luu","year":"2023","journal-title":"Nanoscale"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"109669","DOI":"10.1016\/j.compscitech.2022.109669","article-title":"Mechanical and Magneto-Mechanical Properties of Styrene\u2013Butadiene-Rubber-Based Magnetorheological Elastomers Conferred by Novel Filler\u2013Polymer Interactions","volume":"229","author":"Alam","year":"2022","journal-title":"Compos. Sci. Technol."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Alam, M.N., Kumar, V., Jeong, S.U., and Park, S.S. (2024). The Effect of Rubber\u2013Metal Interactions on the Mechanical, Magneto\u2013Mechanical, and Electrical Properties of Iron, Aluminum, and Hybrid Filler-Based Styrene\u2013Butadiene Rubber Composites. Polymers, 16.","DOI":"10.3390\/polym16172424"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1021\/ct200661p","article-title":"Intercalation of Transition Metals into Stacked Benzene Rings: A Model Study of the Intercalation of Transition Metals into Bilayered Graphene","volume":"8","author":"Youn","year":"2012","journal-title":"J. Chem. Theory Comput."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"6500","DOI":"10.1021\/acs.jpca.7b05759","article-title":"Transition Metal Cation\u2013\u03c0 Interactions: Complexes Formed by Fe2+, Co2+, Ni2+, Cu2+, and Zn2+ Binding with Benzene Molecules","volume":"121","author":"Demircan","year":"2017","journal-title":"J. Phys. Chem. A"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"3327","DOI":"10.1016\/j.compstruct.2012.04.035","article-title":"Vibration Damping Properties of Steel\/Rubber\/Composite Hybrid Structures","volume":"94","author":"Sarlin","year":"2012","journal-title":"Compos. Struct."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1907","DOI":"10.1166\/jnn.2015.10324","article-title":"Vibration Damping Materials and Their Applications in Nano\/Micro-Electro-Mechanical Systems: A Review","volume":"15","author":"Choudhary","year":"2015","journal-title":"J. Nanosci. Nanotechnol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"075017","DOI":"10.1088\/1361-665X\/ab8837","article-title":"Optimization of Magneto-Rheological Elastomers for Energy Harvesting Applications","volume":"29","author":"Diguet","year":"2020","journal-title":"Smart Mater. Struct."},{"key":"ref_43","unstructured":"(2024). Rubber, Vulcanized or Thermoplastic\u2014Determination of Tensile Stress-Strain Properties (Standard No. ISO 37)."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"449","DOI":"10.1016\/j.compositesa.2004.10.004","article-title":"The Effect of Filler\u2013Filler and Filler\u2013Elastomer Interaction on Rubber Reinforcement","volume":"36","author":"Niedermeier","year":"2005","journal-title":"Compos. Part A Appl. Sci. Manuf."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"242901","DOI":"10.1063\/1.3273368","article-title":"Ferroelectric Polymer\/Silver Nanocomposites with High Dielectric Constant and High Thermal Conductivity","volume":"95","author":"Huang","year":"2009","journal-title":"Appl. Phys. Lett."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"710","DOI":"10.1002\/adma.200801758","article-title":"High Dielectric Permittivity and Low Percolation Threshold in Nanocomposites Based on Poly(Vinylidene Fluoride) and Exfoliated Graphite Nanoplates","volume":"21","author":"He","year":"2009","journal-title":"Adv. Mater."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"109639","DOI":"10.1016\/j.compscitech.2022.109639","article-title":"How Do Electromechanical Properties of Dielectric Elastomer Composites Influence Their Energy Harvesting Performances?","volume":"228","author":"Wu","year":"2022","journal-title":"Compos. Sci. Technol."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"016103","DOI":"10.1063\/1.3159040","article-title":"Electron Tunneling in Conductor\u2013Insulator Composites with Spherical Fillers","volume":"106","author":"Ambrosetti","year":"2009","journal-title":"J. Appl. Phys."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"2614","DOI":"10.1002\/pc.26018","article-title":"Role of the Interface on Electron Transport in Electro-Conductive Polymer-Matrix Composite: A Review","volume":"42","author":"Mondal","year":"2021","journal-title":"Polym. Compos."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"3949","DOI":"10.1016\/j.jmrt.2025.04.097","article-title":"Controlling of Tunneling Resistance in Carbon Nanofiber Polymer Composites: A Novel Equation for Polymer Tunneling Resistivity by Quantifiable Parameters","volume":"36","author":"Zare","year":"2025","journal-title":"J. Mater. Res. Technol."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"4205","DOI":"10.33263\/BRIAC95.205216","article-title":"A Review on Giant Piezoelectric Coefficient, Materials and Applications","volume":"9","author":"Ramesh","year":"2019","journal-title":"Biointerface Res. Appl. Chem."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"1700275","DOI":"10.1002\/adem.201700275","article-title":"Temperature Effect on Performance of Triboelectric Nanogenerator","volume":"19","author":"Lu","year":"2017","journal-title":"Adv. Eng. Mater."},{"key":"ref_53","unstructured":"(2026, July 06). X-ray Photoelectron Spectroscopy (XPS) Reference Pages. Available online: https:\/\/www.xpsfitting.com\/."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"475","DOI":"10.1016\/S0079-6700(96)00015-9","article-title":"Vulcanization and Crosslinking in Elastomers","volume":"22","author":"Akiba","year":"1997","journal-title":"Prog. Polym. Sci."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"015303","DOI":"10.1088\/2053-1591\/4\/1\/015303","article-title":"Glass Transition of Polystyrene (PS) Studied by Raman Spectroscopic Investigation of Its Phenyl Functional Groups","volume":"4","author":"Menezes","year":"2017","journal-title":"Mater. Res. Express"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.polymer.2019.05.019","article-title":"Raman Spectroscopy and Molecular Bases of Elasticity: SEBS-Graphite Composites","volume":"176","author":"Chipara","year":"2019","journal-title":"Polymer"}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/18\/15\/1801\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T15:12:40Z","timestamp":1784819560000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/18\/15\/1801"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,23]]},"references-count":56,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["polym18151801"],"URL":"https:\/\/doi.org\/10.3390\/polym18151801","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,23]]}}}