Functionalized wood with tunable tribopolarity for efficient triboelectric nanogenerators

•Efficient approach to increase and tune the triboelectric polarity of native wood•Wood scaffolds are functionalized with ZIF-8 PDMS•Wide selection parameters allows tuning output•Demonstration functional wood TENGs suitable for large-scale applications The energy efficiency buildings could be strongly improved by enabling building materials convert their occupants' mechanical directly into useful electricity. In this regard, approaches based on effects especially promising. Wood is an excellent material, highly appreciated its intrinsic sustainability, low cost, as well aesthetic value. However, due weak polarizability poor performance, use a source has yet exploited. Here, we tackled problem functionalizing PDMS assembling them in nanogenerators (TENGs). Our (FW-TENGs) show potential energy-harvesting floors smart buildings. state-of-art, renewable, sustainable material properties but negligible polarizability. Strategies improve rationally needed further application harvesting We found that becomes more triboelectrically positive when modified situ-grown zeolitic imidazolate framework-8 (ZIF-8), metal-organic framework (MOF), negative coated poly(dimethylsiloxane) (PDMS). A nanogenerator (TENG) made two radial-cut samples (L × R T: 35 20 1 mm3), respectively PDMS, can generate open-circuit voltage (Voc) 24.3 V short-circuit current (Isc) 0.32 ?A upon 50 N, 80 times higher compared wood. demonstrate applicability our TENG (FW-TENG) using it power household lamps, calculators, electrochromic windows. concept “smart building” witnessed ever-increasing attention recent decades. Conventional heavily rely supplies limited lifetime (batteries),1Bell L.E. Cooling, heating, generating power, recovering waste heat thermoelectric systems.Science. 2008; 321: 1457-1461Crossref PubMed Scopus (3781) Google Scholar, 2Fan F.R. Tian Z.Q. Wang Z.L. 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Suntalelat Sripumkhai Pattamang Rujijanagul Inceesungvorn Highly dispersed boosting power-generating 67: 104214Crossref (25) Surface modification allowed researchers change properties, ([email protected]) protected]), enhancing output. changes composition alone cannot considered solely responsible observed behavior. As scaffold, provides increased strength toughness, also micro- nanoscale composite. specific manifests differently wood's structure, depends both chosen species cutting direction. reason, investigated different directions, sizes, composites. resulting optimized displayed over than TENG, devices (from lamps calculators) actuate miniature window, modulate indoor lighting.25Yang X.H. S.H. W.Z. device driven nanogenerator.Energ. 9462-9466Crossref (92) 26Qiu Feng Y.G. Luo N. S.G. D.A. Sandwich-like sound-driven Cu foam.Nano 70: 104543Crossref (17) 27Yeh M.H. P.K. Motion-driven reactions window system.ACS 4757-4765Crossref (124) study will inform design next-generation energy-efficient materials. fabrication represented schematically Figure 1A. Two pieces veneer modified, respectively, particles (by situ growth) spin coating curing). morphological donate or acquire electrons during periodic contact-separation cycles and, consequently, amount electricity produced. Metal electrodes then attached back side each collect transfer electrostatically induced charges through external circuit. principle FW-TENG illustrated 1B, coupled electrification electrostatic induction.2Fan When [email protected] put protected], static sign electrification. Electrons fully balanced, paired There no electron flow circuit at stage (stage I).10Sun Scholar,28Yang Z.H. Y.S. Jing Su Y.J. Hu C.G. Human skin active tactile sensor 2013; 9213-9222Crossref (508) Once layers separated, compensated ones inducing difference across top bottom electrodes. Simultaneously, under action induction. order screen difference, free between conductive load II). Both outputs process until potentials reach equilibrium again III). reverted begin decrease, driving direction original state attained, reversed IV).29Li S.Y. H.Q. Nie Liang Y.X. Tao X.Y. Fu E.G. Manipulating charge density polymers low-energy helium ion irradiation/implantation.Energ. 13: 896-907Crossref It already demonstrated30Wang Maxwell's displacement sensors: origin nanogenerators.Mater. Today. 20: 74-82Crossref (790) Scholar,31Wang first theory equations.Nano 68: 104272Crossref (167) internal determined (first introduced Maxwell 1861, electric moving charges32Zhang Yao Quan L.W. Zheng Theories nanogenerators: comprehensive review.Nanotechnol. 610-625Crossref (8) Scholar), while capacitive conduction current. S1, meet loop. Therefore, physical core generation, manifestation current.31Wang investigate microstructure three (balsa, spruce, yew), widely terms cell porosity 64% 16%, S2 Table S1), 83 kg m?3 814 m?3), were tested present study. Figures 2A, 2B , S3 scanning microscopy (SEM) images cross-cuts (C) balsa, yew. Balsa lightweight, diffuse-porous hardwood species, mainly vessels, parenchyma cells, fibers aligned along longitudinal spruce yew, softwoods relatively similar anatomical features. average, yew tracheids lower lumen diameter wall thickness reflected much density.33Keunecke Eder Niemz Micromechanical common (Taxus baccata) Norway (Picea abies) transition subjected tension.J. 54: 420-422Crossref (21) Different morphologies, turn microstructures. morphologies originating directions. Spruce cut planes: cross (C), radial (R), tangential (T). 2B–2D, cuts microstructures anisotropy wood, roughness. Nanocrystals grown two-step process. First, pretreated alkaline solution nucleation sites, promoted stable attachment nanocrystals. Then, nanocrystals stepwise zinc nitrate Zn(NO3)2 2-methylimidazole (2-MeIm) solutions. size tuned controlling ratio ligand (Zn cations, Zn2+). 2-MeIm/Zn2+ molar 5 20, average ?616 nm ?1,008 nm, associated distribution broadened. (Figures S4 S5). morphology sample, prepared 2E–2H S6. seen 2E, analogue protected](C) dramatically affected pretreatment, partially removes lignin hemicelluloses, causing walls wrinkle extensive shrinkage after drying (Figure S7).19Tu SEM 2I–2L S8. Compared smoother. cross-cut longer macroporous, since entirely covering whole lumina, forming concave surface. film within 10 ?m, smaller (1 mm), S9. These results introduces relevant changes. By ZIF-8, surface's changed 2M 2N S10). Fourier transform infrared (FTIR) spectra protected](C), spruce(C) 2M. strongest absorption bands 796 cm? (Si–C stretching Si–CH3) 1,258 (deformation –CH3 Si–CH3), confirming presence surface.34Johnson Gao Shields C.W. Smith Efimenko Cushing Genzer Lopez G.P. Elastomeric microparticles acoustic mediated bioseparations.J. Nanobiotechnol. 11: 1-8Crossref (132) sample shows 1,147 cm?1, 422 759 C–N Zn–N bonds, out-of-plane bending 2-MeIm ring, confirms successful ZIF-8. FTIR only notable exception being explained taking X-ray diffraction (XRD) patterns 2N). strong peaks 2? = 7.48, 10.54, 12.88, 14.80, 16.58, 18.16°, correspond planes (011), (002), (112), (022), (013), (222), indicate high crystallinity 5-, 10-, 20-ZIF-8 samples. XRD without crystals, suggesting result formation S11). Zn incorporated kind measured inductively plasma-optical emission spectrometry (ICP-OES) calculate percentage MOF loading. Results (Table S2) showed had contents, 11.0 wt %, 9.3 8.8 Zn-based unknown (sample 1-(MeIm/Zn)@spruce(C)). Higher usually area, TENG.10Sun Scholar,35Lee Hwang Triboelectric pendulum oscillation energy.Nano 2: 1113-1120Crossref (106) excessively rough produce tip-to-tip contacts materials, incomplete consequently decreasing output.36Park Seol M.L. S.B. Choi Y.K. engineering electrodeposited gold nanoflower structure.Sci. Rep. 13866Crossref (43) Hence, control vital Although real area proportional roughness, quantitative analysis remains open challenge many factors need taken applied load, number microcontacts, conductance surfaces).37Persson B.N.J. Contact mechanics randomly surfaces.Surf. 2006; 61: 201-227Crossref (479) Scholar,38Yang W.X. Y.Q. Liu Fundamental research micro-/nano-textured nanogenerator.Nano 57: 41-47Crossref (46) empirical conventionally adopted, differences related micro/nano-structuration techniques, including photolithography templates, nanoimprint, physical/chemical etching.39Dudem Y.H. Leem Yu J.S. subwavelength-architectured nanoporous anodic aluminum oxide template.ACS 20520-20529Crossref (67) 40Su M.D. Asymmetrical controllable discharge.Adv. 26: 5524-5533Crossref 41Zhou Xue Multilayered electret films Res. 1442-1451Crossref (93) methods require complex processes dedicated instrumentation. Here take advantage variety micro/nano-roughness functionalization PDMS. 3A, 3B, S12 3D profiling respectively. S3, same lead Native balsa(C) highest (Ra) value 11.9 yew(C) lowest (6.5 ?m). 3C tangential- Ra (11.4 ?m), spruce(R) spruce(T) values, 6.3 7.6 ?m S3). structure. representative inherent surface, originates arrangement microscale cells. 3E S13 significantly reduced microscale, consistent results. Modifying scaffold certain extent overall 3F S14 S3), time atomic force (AFM), imaging earlywood's scan 2.5 ?m. 3G–3J S4, 2-Melm/Zn2+ gradually 169.1 286.5 nm. 1, 1-(MeIm/Zn)@spruce(C) 37.1 Modification valid adjust following, plays essential