Scalable Cellulose-Templated Micro/Nano Clusters with Hierarchical Nanoconfined Scattering via Interface Self-Assembly for Efficient Passive Daytime Radiative Cooling

Abstract

Passive daytime radiative cooling (PDRC) offers a zero-energy solution to mitigate the global energy crisis, yet insufficient solar reflection and complex fabrication procedures may hinder its practical applications. Herein, this study presents hierarchically structured zinc oxide (ZnO) clusters regulated by the matrix-regenerated cellulose fibrils (RCFs) template for efficient PDRC. A proposed ZnCl₂-mediated cellulose dissolution-regeneration strategy is developed to yield hydroxyl-rich RCFs with anchored Zn²⁺ ions, thereby facilitating the interfacial self-assembly of well-dispersed, flower-like ZnO clusters. Acting as efficient scattering centers, these hierarchical micro/nano architectures enhance light scattering via multiple internal reflections, endowing the ZnO/RCFs composites with an ultrahigh solar reflectivity (as high as 99.6% in the visible-light region to the near-infrared range) and ultra violet (UV) resistance (> 240 h). Based on experimental results and theoretical simulations, a 'hierarchical-confined scattering' effect is proposed to clarify this mechanism. Combined with the high infrared emissivity (96.7%) in the mid-infrared region of the RCFs matrix, this synergy enables a remarkable daytime sub-ambient cooling of 11.2 °C. Energy consumption simulations further demonstrate its significant energy-saving potential across diverse climatic zones in China by reducing cooling demand. Notably, the ZnO/RCFs composites can be processed into various PDRC products via different techniques. This work offers a scalable and sustainable strategy to develop high-performance PDRC materials to address escalating global energy challenges.

Graphical Abstract

Keywords

Regenerated cellulose fibrils / Passive daytime radiative cooling / Hierarchical ZnO clusters / Optical scattering / Energy saving

References

[1] Reisinger A, Fuglestvedt JS, Pirani A, Geden O, Jones CD, Maharaj S, Poloczanska ES, Morelli A, Johansen TG, Adler C, Betts RA, Seneviratne SI. Overshoot: a conceptual review of exceeding and returning to global warming of 1.5 °C. Annu Rev Environ Resour, 2025, 50: 185

[2] Law A, Saunders P, Middleton J, McCoy D. Global warming must stay below 1.5 °C. BMJ, 2018, 363 ArticleID: k4410

[3] Munday G, Jones CD, Steinert NJ, Mathison C, Burke EJ, Smith C, Huntingford C, Varney RM, Wiltshire AJ. Risks of unavoidable impacts on forests at 1.5 °C with and without overshoot. Nat Clim Change, 2025, 15: 650

[4] Heikonen S, Heino M, Jalava M, Siebert S, Viviroli D, Kummu M. Climate change threatens crop diversity at low latitudes. Nat Food, 2025, 6: 331

[5] Schuster L, Maussion F, Rounce DR, Ultee L, Schmitt P, Lacroix F, Frölicher TL, Schleussner C-F. Irreversible glacier change and trough water for centuries after overshooting 1.5 °C. Nat Clim Change, 2025, 15: 634

[6] Alam MA, Irshad K, Rehman S, Masood F, Zayed ME. Recent developments in renewable energy assisted cold thermal energy storage air conditioning systems. J Energy Storage, 2025, 127 ArticleID: 117124

[7] Yin XB, Yang RG, Tan G, Fan SH. Terrestrial radiative cooling: using the cold universe as a renewable and sustainable energy source. Science, 2020, 370: 786

[8] Cheng YY, Chen YJ, Hu XY, Liu L, Ye XL, Zhang JX, Ma XM, Wang J. Ceramic matrix composites as self-standing monoliths and coatings for thermal superinsulation and passive daytime radiative cooling. Adv Funct Mater, 2025, 35: 2504931

[9] Yao PC, Chen ZP, Liu TJ, Liao XB, Yang ZW, Li JL, Jiang Y, Xu N, Li W, Zhu B, Zhu J. Spider-silk-inspired nanocomposite polymers for durable daytime radiative cooling. Adv Mater, 2022, 34: 2208236

[10] Zhou P, Jiang GY, Wang YY, Tian YQ, Zhang XX. Self-adaptive and large-area sprayable thermal management coatings for energy saving. Nat Commun, 2025, 16: 3791

[11] Fei JP, Zhang X, Han D, Lei Y, Xie F, Zhou K, Koh S-W, Ge JY, Zhou H, Wang XL, Wu XH, Tan J-Y, Gu YHH, Long YP, Koh ZH, Wang S, Du PW, Mi TW, Ng B-F, Cai LL, Feng C, Gan QQ, Li H. Passive cooling paint enabled by rational design of thermal-optical and mass transfer properties. Science, 2025, 388: 1044

[12] Wu XK, Li JL, Xie F, Wu X-E, Zhao SM, Jiang QY, Zhang SL, Wang BS, Li YR, Gao D, Li R, Wang F, Huang Y, Zhao YL, Zhang YY, Li W, Zhu J, Zhang RF. A dual-selective thermal emitter with enhanced subambient radiative cooling performance. Nat Commun, 2024, 15: 815

[13] Peng F, Ren KL, Zheng GQ, Dai K, Gao CJ, Liu CT, Shen CY. Continuous sandwiched film containing oriented ZnO@HDPE microfiber for passive radiative cooling. Adv Funct Mater, 2024, 34 ArticleID: 2400221

[14] Lin KX, Chen SR, Zeng YJ, Ho TC, Zhu YH, Wang X, Liu FY, Huang BL, Chao CY-H, Wang ZK, Tso CY. Hierarchically structured passive radiative cooling ceramic with high solar reflectivity. Science, 2023, 382: 691

[15] Xiong LH, Wei Y, Chen CL, Chen X, Fu Q, Deng H. Thin lamellar films with enhanced mechanical properties for durable radiative cooling. Nat Commun, 2023, 14: 6129

[16] Song JN, Zhang WL, Sun ZN, Pan MY, Tian F, Li XH, Ye M, Deng X. Durable radiative cooling against environmental aging. Nat Commun, 2022, 13: 4085

[17] Bond WL. Measurement of the refractive indices of several crystals. J Appl Phys, 1965, 36: 1674

[18] Srikant V, Clarke DR. On the optical band gap of zinc oxide. J Appl Phys, 1998, 83: 5447

[19] Cai LL, Song AY, Li W, Hsu P-C, Lin DC, Catrysse PB, Liu YY, Peng YC, Chen J, Wang HX, Xu JW, Yang AK, Fan SH, Cui Y. Spectrally selective nanocomposite textile for outdoor personal cooling. Adv Mater, 2018, 30 ArticleID: 1802152

[20] Wang CH, Liu MX, Jiang ZY. TiO₂ particle agglomeration impacts on radiative cooling films with a thickness of 50 μm. Appl Phys Lett, 2022, 121 ArticleID: 202204

[21] Song QM, Kubacki E, Berger A, Retsch M. Cool kitchen: processing starch and eggshell powder into sustainable coatings for passive daytime cooling. Adv Funct Mater, 2026, 36 ArticleID: e13897

[22] Hu XP, Quan BQ, Shi ZJ, Zhao XY, Lu GC, Ding Y, Lai JC, Qu JP, Peng YC, Lu X. Bioinspired hierarchical radiative-phase change hybrid cooling composite with record-breaking cooling power. Adv Mater, 2026, 38 ArticleID: e10988

[23] Huang WL, Chen YJ, Luo Y, Mandal J, Li WX, Chen MJ, Tsai C-C, Shan ZQ, Yu NF, Yang Y. Scalable aqueous processing-based passive daytime radiative cooling coatings. Adv Funct Mater, 2021, 31: 2010334

[24] Li XK, Wang YY, Zhang XX. Strong, healable materials with bio-like ordered architectures and versatile functionality. SusMat, 2024, 4 ArticleID: e248

[25] Zhou XF, Liu SQ, Xiang HL, Li XW, Wang CY, Wu Y, Li G. Three-dimensional SERS substrates: architectures, hot spot engineering, and biosensing applications. Biosensors, 2025, 15 ArticleID: 555

[26] Zhao X, Li Q, Xu LX, Zhang Z, Kang Z, Liao QL, Zhang Y. Interface engineering in 1D ZnO-based heterostructures for photoelectrical devices. Adv Funct Mater, 2022, 32 ArticleID: 2106887

[27] Sun HD, Tang FJ, Bi YH, Sun H, Huang LL, Jiang F, Chen LH, Li JG. Hierarchically porous cellulose membrane via self-assembly engineering for ultra high-power thermoelectrical generation in natural convection. Adv Funct Mater, 2023, 33 ArticleID: 2307960

[28] Peng ZC, Zeng FR, Zeng ZW, Su PG, Tang PJ, Liu BW, Zhang Y, Wang YZ, Zhao HB. Scalable low-carbon ambient-dried foam-like aerogels for radiative cooling with extreme environmental resistance. Adv Mater, 2025, 37 ArticleID: 2505224

[29] Ovalle-Serrano SA, Carrillo VS, Blanco-Tirado C, Hinestroza JP, Combariza MY. Controlled synthesis of ZnO particles on the surface of natural cellulosic fibers: effect of concentration, heating and sonication. Cellulose, 2015, 22: 1841

[30] Wang JJ, Yang C, Zhang LL, Cui CW, Zeng XF, Chen JF. Monodispersed zinc oxide nanoparticles as multifunctional additives for polycarbonate thermoplastic with high transparency and excellent comprehensive performance. Adv Compos Hybrid Mater, 2022, 5: 2936

[31] Shi C, Zhang LL, Shi ZJ, Wang ZG, Ma JX. Mechanistic investigation of cellulose regulating the morphology and photocatalytic activity of Al-doped ZnO. Int J Biol Macromol, 2023, 228: 435

[32] Duan C, Liu XS, Tian GD, Zhang D, Wen YJ, Che YY, Xie ZY, Ni YH. A one-stone-two-birds strategy for cellulose dissolution, regeneration, and functionalization as a photocatalytic composite membrane for wastewater purification. Int J Biol Macromol, 2024, 274 ArticleID: 133317

[33] Ritter M, Maćkosz K, Garemark J, Kürsteiner R, Dreimol CH, Utke I, Burgert I, Panzarasa G. Piezoelectric and photoconductive zinc oxide–wood hybrids obtained by atomic layer deposition. ACS Nano, 2025, 19: 15161

[34] Tong ZH, Wang W, Zeng SQ, Sun YX, Meng J, Liu YZ, Xia QQ, Yu HP. Hydrogen bond reconstruction strategy for eutectic solvents that realizes room-temperature dissolution of cellulose. Green Chem, 2022, 24: 8760

[35] Sen S, Losey BP, Gordon EE, Argyropoulos DS, Martin JD. Ionic liquid character of zinc chloride hydrates define solvent characteristics that afford the solubility of cellulose. J Phys Chem B, 2016, 120: 1134

[36] Lin CJ, Li KQ, Li M, Dopphoopha B, Zheng JZ, Wang JZ, Du SS, Li Y, Huang BL. Pushing radiative cooling technology to real applications. Adv Mater, 2025, 37 ArticleID: 2409738

[37] Geng AB, Guo SY, Yao QY, Wu XD, Zhao X, Ding CX, Cai CY. Bioinspired cellulose-based hygroscopic aerogel with hierarchical encapsulation design for sustainable passive daytime cooling via synergistic dual mechanisms. Small, 2025, 21 ArticleID: e08254

[38] Feng SJ, Yao L, Feng MX, Cai HR, He X, He M, Bu XH, Zhou YM. Regeneration of pea-pod-like cellulose acetate fibers as aerogel-derived boards for building thermal regulation and carbon reduction. Adv Fiber Mater, 2024, 6: 570

[39] Xu RL. Light scattering: a review of particle characterization applications. Particuology, 2015, 18: 11

[40] Felicelli A, Katsamba I, Barrios F, Zhang Y, Guo ZQ, Peoples J, Chiu G, Ruan XL. Thin layer lightweight and ultrawhite hexagonal boron nitride nanoporous paints for daytime radiative cooling. Cell Rep Phys Sci, 2022, 3 ArticleID: 101058

[41] Wu RH, Sui CX, Chen T-H, Zhou ZR, Li QZ, Yan GB, Han Y, Liang JW, Hung P-J, Luo E, Talapin DV, Hsu P-C. Spectrally engineered textile for radiative cooling against urban heat islands. Science, 2024, 384: 1203

[42] Yang ZB, Lu HT, Li Q, Guo XT, Li Q, Zhou HJ, Wang BX, Qi YL, Chen H-C, Yang MF, Tian T, Yang H, Ding JN, Pang H. Nano/micro metal–organic framework-derived ceramics for sustainable energy saving/capturing. Adv Mater, 2026, 38 ArticleID: e12289

[43] Cai CY, Wu XD, Cheng FL, Ding CX, Wei ZC, Wang X, Fu Y. Cellulose metamaterials with hetero-profiled topology via structure rearrangement during ball milling for daytime radiative cooling. Adv Funct Mater, 2024, 34 ArticleID: 2405903

[44] Li PL, Wang A, Fan JJ, Kang Q, Jiang PK, Bao H, Huang XY. Thermo-optically designed scalable photonic films with high thermal conductivity for subambient and above-ambient radiative cooling. Adv Funct Mater, 2022, 32 ArticleID: 2109542

[45] Wang T, Wu Y, Shi L, Hu XH, Chen M, Wu LM. A structural polymer for highly efficient all-day passive radiative cooling. Nat Commun, 2021, 12: 365

[46] Li HL, Li X, Pan MY, Ding ZM, Zhao JP, Moita ASOH, Li Y, Pattelli L, Xu HB. Flexible ceramic radiative cooling membranes with high reflectivity in solar spectrum, excellent UV and fire resistance. Adv Funct Mater, 2025, 36: 10

[47] Ma WL, Li X, Zhang LL, Zheng Y, Xi Y, Ma JL, Wang ZG. Novel insights on room temperature-induced cellulose dissolution mechanism via ZnCl₂ aqueous solution: migration, penetration, interaction, and dispersion. Int J Biol Macromol, 2024, 272 ArticleID: 132912

[48] Tian GD, Duan C, Zhao BK, Yang K, Guo JY, Wen YJ, Zhou BX, Wang J, Ni YH. Janus structured cellulose-based aerogel with vertical channels and conical roof for efficient solar-driven water evaporation and pollutant degradation. Carbohydr Polym, 2025, 360 ArticleID: 123622

[49] Wu JL, Ma XZ, Gnanasekar P, Wang F, Zhu J, Yan N, Chen J. Superhydrophobic lignin-based multifunctional polyurethane foam with SiO₂ nanoparticles for efficient oil adsorption and separation. Sci Total Environ, 2023, 860 ArticleID: 160276

[50] Xu J, Chen KW, Maturilli A, Laroche A, Meng LS, Knollenberg J, Seeger S. Biomass-Derived polysilsesquioxane nanofilament reinforced porous aerogel for durable passive radiative cooling across all say and weather conditions. ACS Nano, 2025, 19: 44

[51] Xu JN, Xie W, Han HX, Xiao CY, Li J, Zhang YF, Chen SW, Zhao BY, Zhang D, Zhou H. Radiative cooling materials for extreme environmental applications. Nano-Micro Lett, 2025, 17: 324

Funding

National Natural Science Foundation of China(22178206)

the State Key Laboratory of Bio-based Fiber Materials(SKLBFM202519)

RIGHTS & PERMISSIONS

Donghua University, Shanghai, China

Just Accepted

This article has successfully passed peer review and final editorial review, and will soon enter typesetting, proofreading and other publishing processes. The currently displayed version is the accepted final manuscript. The officially published version will be updated with format, DOI and citation information upon launch. We recommend that you pay attention to subsequent journal notifications and preferentially cite the officially published version. Thank you for your support and cooperation.