Polymer engineering in hydrogel-based moisture-electric generators for green energy harvesting

Abstract

Hydrogel-based moisture-electric generators (HMEGs) have emerged as a promising technology for sustainable energy harvesting by utilizing ambient moisture. This article highlights recent advancements in HMEG development, focusing on innovative hydrogel designs to enhance energy output and practical applicability. Hydrogels provide a highly efficient medium for water absorption and ion transport, but their limited moisture generation performance necessitates polymer engineering strategies. Protonation doping and the incorporation of other cations, such as sodium ions, have been shown to significantly improve electrical output. Furthermore, dual-network hydrogels enhance both mechanical robustness and energy conversion efficiency. Future research should focus on improving scalability through large-scale fabrication techniques, enhancing durability under varying environmental conditions, and optimizing hydrogel properties for wearable and implantable applications. With continued material and engineering innovations, HMEGs hold great potential for advancing self-powered electronics and sustainable energy solutions.

Keywords

Hydrogels / moisture-electric generators / energy harvesting / nanogenerators

References

[1] Mohan B,Ahmadov E,Ren P.Harvesting sustainable osmotic energy: the art of nanofluidic hydrogel membranes.J Energy Chem2025;105:577-94

[2] Mohan B,Gupta RK,Ren P.Advanced materials for energy harvesting: exploring the potential of MOFs and MXene membranes in osmotic energy applications.Prog Mater Sci2025;152:101457

[3] Cui Y,Yao H.Single-junction organic photovoltaic cell with 19% efficiency.Adv Mater2021;33:2102420

[4] Aydin E,De Bastiani M.Pathways toward commercial perovskite/silicon tandem photovoltaics.Science2024;383:eadh3849

[5] Chen J,Su ZH.Magnetic-biased chiral molecules enabling highly oriented photovoltaic perovskites.Natl Sci Rev2024;11:nwad305 PMCID:PMC10776365

[6] Zhang W,Yan X,Yang Z.Challenges and progress of chemical modification in piezoelectric composites and their applications.Soft Sci2023;3:19

[7] Jarkov V,Tsikriteas ZM,Adams C.3D piezoelectric cellulose composites as advanced multifunctional implants for neural stem cell transplantation.Cell Rep Phys Sci2025;6:102368

[8] Chen A,Li Y.3D/4D printed bio-piezoelectric smart scaffolds for next-generation bone tissue engineering.Int J Extrem Manuf2023;5:032007

[9] Liu X,Du Y,Eklund P.Enhanced thermoelectric properties of flexible self-supporting carbon nanotube film/polypyrrole composites.Cell Rep Phys Sci2024;5:102163

[10] Tang X,Sun Q.Recent progress of biosensors based on thermoelectric effects for monitoring physical activity and environment monitoring.Soft Sci2025;5:11

[11] Chang Z,Sun Z.First-principles investigation of the significant anisotropy and ultrahigh thermoelectric efficiency of a novel two-dimensional Ga₂I₂S₂ at room temperature.Int J Extrem Manuf2022;4:025001

[12] Chen S,Mao L.Piezocatalytic medicine: an emerging frontier using piezoelectric materials for biomedical applications.Adv Mater2023;35:e2208256

[13] Ji J,Shan Y.Research trends of piezoelectric nanomaterials in biomedical engineering.Adv NanoBiomed Res2023;3:2200088

[14] Pan X,Wang Y,Cai H.Mechanical energy harvesting based on the piezoelectric materials: recent advances and future perspectives.Chem Eng J2024;497:154249

[15] Mahanty B,Lee D.Advancements in polymer nanofiber-based piezoelectric nanogenerators: revolutionizing self-powered wearable electronics and biomedical applications.Chem Eng J2024;495:153481

[16] Tsikriteas ZM,Bowen CR.Exploring lead-free materials for screen-printed piezoelectric wearable devices.Cell Rep Phys Sci2024;5:101962

[17] Zhang C,Wang S,Zhang Y.Recent progress of wearable piezoelectric nanogenerators.ACS Appl Electron Mater2021;3:2449-67

[18] Li Q,Cheng D.Moist-electric generator with efficient output and scalable integration based on carbonized polymer dot and liquid metal active electrode.Adv Funct Mater2023;33:2211013

[19] Izadgoshasb I.Piezoelectric energy harvesting towards self-powered Internet of Things (IoT) sensors in smart cities.Sensors2021;21:8332 PMCID:PMC8703737

[20] Guo L.Non-intrusive movable energy harvesting devices: materials, designs, and their prospective uses on transportation infrastructures.Renew Sustain Energy Rev2022;160:112340

[21] Akin-Ponnle AE.Energy harvesting mechanisms in a smart city - a review.Smart Cities2021;4:476-98

[22] Cao Y,Li Z.Advanced design of high-performance moist-electric generators.Adv Funct Mater2023;33:2301420

[23] Feng J,Wang S.Graphene oxide-based planar hygroelectric generator and its applications in a flexible self-powered sensing system.ACS Appl Nano Mater2024;7:1646-54

[24] Feng J,Hui Z.High-performance magnesium-carbon nanofiber hygroelectric generator based on interface-mediation-enhanced capacitive discharging effect.ACS Appl Mater Interfaces2020;12:24289-97

[25] Shen D,Zhao J.Ionic hydrogel-based moisture electric generators for underwater electronics.Adv Sci2024;11:e2408954 PMCID:PMC11578371

[26] Zhao F,Zhang Z,Qu L.Direct power generation from a graphene oxide film under moisture.Adv Mater2015;27:4351-7

[27] Sun Z,Wang L.Emerging design principles, materials, and applications for moisture-enabled electric generation.eScience2022;2:32-46

[28] Ni F,Zhang C.Hygroscopic polymer gels toward atmospheric moisture exploitations for energy management and freshwater generation.Matter2022;5:2624-58

[29] Wei Q,Yuan Z.Moisture electricity generation: mechanisms, structures, and applications.Nano Res2023;16:7496-510

[30] Shen D,Peng P.Moisture-enabled electricity generation: from physics and materials to self-powered applications.Adv Mater2020;32:e2003722

[31] Yan H,Qi R.A review of humidity gradient-based power generator: devices, materials and mechanisms.Nano Energy2022;101:107591

[32] Wang H,He T.Bilayer of polyelectrolyte films for spontaneous power generation in air up to an integrated 1,000 V output.Nat Nanotechnol2021;16:811-9

[33] He T,Lu B.Fully printed planar moisture-enabled electric generator arrays for scalable function integration.Joule2023;7:935-51

[34] Liu C,Guan P.Unveil the triple roles of water molecule on power generation of MXene derived TiO₂ based moisture electric generator.Adv Energy Mater2024;14:2400590

[35] Shen D,Zou G,Duley WW.Self-powered wearable electronics based on moisture enabled electricity generation.Adv Mater2018;30:1705925

[36] Akbarisehat A.Electricity generation via metal oxide-air moist interaction.Mater Today Commun2024;40:109744

[37] Dinh Trung, V.; Chen, S.; Xia, H.; Natsuki, T.; Ni, Q. A moisture-induced electric generator with high output voltage for self-powered wearable electronics.ChemNanoMat2022;8:e202200395

[38] Liu H,Zhang X.Graphene oxide sponge with gradient porosity for moisture-electric generator.J Bionic Eng2025;22:783-92

[39] Qi X,Chi C.Ultralight PEDOT:PSS/graphene oxide composite aerogel sponges for electric power harvesting from thermal fluctuations and moist environment.Nano Energy2020;77:105096

[40] Huang Y,Shi G.Highly efficient moisture-triggered nanogenerator based on graphene quantum dots.ACS Appl Mater Interfaces2017;9:38170-5

[41] Feng Z,Zhu R.Two-dimensional nanomaterials for moisture-electric generators: a review.ACS Appl Nano Mater2022;5:12224-44

[42] Zhao K,Yu ZG.Humidity-tolerant moisture-driven energy generator with MXene aerogel-organohydrogel bilayer.ACS Nano2023;17:5472-85

[43] Li L,Hao M.Moisture-driven power generation for multifunctional flexible sensing systems.Nano Lett2019;19:5544-52

[44] Feng J,Sun Z,Li X.Multifunctionally moist-electric generator for self-powered ultra-fast sensing based on laterally dual gradient.Nano Energy2024;123:109409

[45] Zhang R,Wan Z.High-performance, flexible moist-electric generator for self-powered wearable wireless sensing.Chem Eng J2024;502:157695

[46] Gao H,Li W.High-performance biomass moisture-electric generators derived from Distillers’ spent grains: synthesis, photothermal enhancement, and environmental sensing applications.Chem Eng J2025;504:158880

[47] Yan R,Wang H.Autonomous, moisture-driven flexible electrogenerative dressing for enhanced wound healing.Adv Mater2025;37:e2418074

[48] Zhang H,Wang B.High-performance, highly stretchable, flexible moist-electric generators via molecular engineering of hydrogels.Adv Mater2023;35:2300398

[49] Wang Z,Zhang L,Xu X.Highly strong, tough, and cryogenically adaptive hydrogel ionic conductors via coordination interactions.Research2024;7:0298 PMCID:PMC10786319

[50] Khan M,Sher M.Flexible ionic conductive hydrogels with wrinkled texture for flexible strain transducer with language identifying diversity.Chem Mater2024;36:4703-13

[51] Chen D,Zhu H,Wang W.Anti-freezing, tough, and stretchable ionic conductive hydrogel with multi-crosslinked double-network for a flexible strain sensor.Chem Eng J2024;480:148192

[52] Wu Z,Xu Q.Poly(vinyl alcohol)/polyacrylamide double-network ionic conductive hydrogel strain sensor with high sensitivity and high elongation at break.J Polym Sci2024;62:4599-611

[53] Lei T,Feng Y.PNIPAAm-based temperature responsive ionic conductive hydrogels for flexible strain and temperature sensing.J Colloid Interface Sci2025;678:726-41

[54] Ara L,Khan M,Shah LA.Dually-crosslinked ionic conductive hydrogels reinforced through biopolymer gellan gum for flexible sensors to monitor human activities.Int J Biol Macromol2024;276:133789

[55] Chen M,Chen X.A novel multifunction of wearable ionic conductive hydrogel sensor for promoting infected wound healing.Appl Mater Today2024;39:102298

[56] He P,Pan X.Anti-freezing and moisturizing conductive hydrogels for strain sensing and moist-electric generation applications.J Mater Chem A2020;8:3109-18

[57] Pan X,Guo R.An adaptive ionic skin with multiple stimulus responses and moist-electric generation ability.J Mater Chem A2020;8:17498-506

[58] He P,Hu K.Tough and super-stretchable conductive double network hydrogels with multiple sensations and moisture-electric generation.Chem Eng J2021;414:128726

[59] Yang S,Chen W.Ionic Hydrogel for efficient and scalable moisture-electric generation.Adv Mater2022;34:e2200693

[60] Cheng Y,Zhu T,Huang J.Light-assisted polyproton dissociated PAAm-PA hydrogel-based moisture-driven electricity generator with a broad operating range.Adv Funct Mater2025;35:2415533

[61] Mo J,Lin X.Sulfated cellulose nanofibrils-based hydrogel moist-electric generator for energy harvesting.Chem Eng J2024;491:152055

[62] Yang S,Mao J.Green moisture-electric generator based on supramolecular hydrogel with tens of milliamp electricity toward practical applications.Nat Commun2024;15:3329 PMCID:PMC11026426

[63] Huang Z,Ying W.A hydrogel-based moist-electric generator with superior energy output and environmental adaptability.Nano Energy2024;126:109673

[64] Li F,Li B.Water-triboelectrification-complemented moisture electric generator.ACS Nano2024;18:30658-67

[65] Cheng Y,He Q.Hydrogel-based moisture electric generator with high output performance induced by proton hopping.Adv Funct Mater2025;2500186

[66] Huang G,Zhang H,Deng Y.A double-gradient structured hydrogel for an efficient moisture-electric generator.Chem Eng J2025;504:158878

[67] Guchait A,Goswami DK,Mondal T.Elastomeric ionic hydrogel-based flexible moisture-electric generator for next-generation wearable electronics.ACS Appl Mater Interfaces2024;16:46844-57

[68] Fang J,Duan P.Efficient and cold-tolerant moisture-enabled power generator combining ionic diode and ionic hydrogel.Mater Horiz2024;11:1261-71

[69] Ma G,Zhou X.PVA–PNIPAM hydrogel-based moisture-electric generators with tunable pore structures for enhanced power generation.ACS Appl Polym Mater2024;6:7066-76

[70] Yu F,Yang X.Moisture-electric generators working in subzero environments based on laser-engraved hygroscopic hydrogel arrays.ACS Nano2025;19:3807-17

[71] Wen X,Xie X.High-performance fully stretchable moist-electric generator.Adv Funct Mater2024;34:2311128

[72] Zhang H,Zhou Y,Cai H.High-performance and anti-freezing moisture-electric generator combining ion-exchange membrane and ionic hydrogel.Small2025;21:e2410609

[73] Duan W,Wang Z.Silicon nanowire/ionic hydrogel-based hybrid moist-electric generators with enhanced voltage output and operational stability.Energy Environ Sci2024;17:3788-96

[74] Zhang J,Lei L.Rapid preparation of a self-adhesive PAA ionic hydrogel using lignin sulfonate–Al³⁺ composite systems for flexible moisture-electric generators.J Mater Chem A2023;11:3546-55

[75] Yan H,Liu Z,Dong C.Unlocking the potential of hydrogel-electrode electrical double layer for high-performance moisture-enabled electric generators.Device2025;3:100568