| 1. |
- Gao, Ying, et al.
(författare)
-
Gradience Free Nanoinsertion of Fe3O4 into Wood for Enhanced Hydrovoltaic Energy Harvesting
- 2023
-
Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 11:30, s. 11099-11109
-
Tidskriftsartikel (refereegranskat)abstract
- Hydrovoltaic energy harvesting offers the potential to utilize enormous water energy for sustainable energy systems. Here, we report the utilization and tailoring of an intrinsic anisotropic 3D continuous microchannel structure from native wood for efficient hydrovoltaic energy harvesting by Fe3O4 nanoparticle insertion. Acetone-assisted precursor infiltration ensures the homogenous distribution of Fe ions for gradience-free Fe3O4 nanoparticle formation in wood. The Fe3O4/wood nanocomposites result in an open-circuit voltage of 63 mV and a power density of ∼52 μW/m2 (∼165 times higher than the original wood) under ambient conditions. The output voltage and power density are further increased to 1 V and ∼743 μW/m2 under 3 suns solar irradiation. The enhancement could be attributed to the increase of surface charge, nanoporosity, and photothermal effect from Fe3O4. The device exhibits a stable voltage of ∼1 V for 30 h (3 cycles of 10 h) showing good long-term stability. The methodology offers the potential for hierarchical organic-inorganic nanocomposite design for scalable and efficient ambient energy harvesting.
|
|
| 2. |
- Gao, Ying, et al.
(författare)
-
Scalable hierarchical wood/ZnO nanohybrids for efficient mechanical energy conversion
- 2023
-
Ingår i: Materials & design. - : Elsevier BV. - 0264-1275 .- 1873-4197. ; 226
-
Tidskriftsartikel (refereegranskat)abstract
- Owing to the hierarchical structure, easy multi-functionalization and favorable mechanical properties, wood could harvest electricity from mechanical energy through piezoelectric behavior. In this work, a scalable method to synthesize wood/ZnO composite with multilayered ZnO morphologies is reported for efficient mechanical energy conversion. The synthesis includes charged wood template fabrication, precursor infiltration, and ZnO hydrothermal growth, resulting in controlled ZnO morphologies and distributions while maintaining the hierarchical structure of the wood. Stereo-digital image correlation (stereo-DIC) investigated the relationship between deformation and piezoelectric performance, which revealed the homogeneous distribution of multilayered ZnO enhance piezoelectric performance. The output voltage of wood/ZnO was 1.5 V under periodic mechanical compression (8–10 N) for 300 cycles, while the output current was 2.91 nA. The scalable synthesis strategy and piezoelectric performance are significant for the design of advanced wood nanocomposites for sustainable and efficient energy conversion systems.
|
|
| 3. |
- Gao, Ying, et al.
(författare)
-
ZnO microrods sandwiched between layered CNF matrix : Fabrication, stress transfer, and mechanical properties
- 2023
-
Ingår i: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 305
-
Tidskriftsartikel (refereegranskat)abstract
- Functional metal oxide particles are often added to the polymers to prepare flexible functional polymer com-posites with adequate mechanical properties. ZnO and cellulose nanofibrils (CNF) outstand among these metal oxides and the polymer matrices respectively due to their various advantages. Herein, we in situ prepare ZnO microrods in the presence of CNF, which resultes in a layered composite structure. The ZnO microrods are sandwiched between the CNF layers and strongly bind to highly charged CNF, which provides a better stress transfer during mechanical activity. Digital image correction (DIC) and finite element analysis-based computa-tional homogenization methods are used to investigate the relationship between mechanical properties and composite structure, and the stress transfer to the ZnO microrods. Full-field strain measurements in DIC reveal that the in situ ZnO microrods preparation leads to their homogenous distribution in the CNF matrix unlike other methods, which require external means such as ultrasonication. The computational homogenization technique provides a fairly good insight into the stress transfer between constituents in microstructure as well as a good prediction of macroscopic mechanical properties, which otherwise, would be challenging to be assessed by any ordinary mechanical testing in the layered composites. Finally, we also demonstrate that these composites could be used as physiological motion sensors for human health monitoring.
|
|
| 4. |
- Garemark, Jonas, et al.
(författare)
-
Advancing Hydrovoltaic Energy Harvesting from Wood through Cell Wall Nanoengineering
- 2023
-
Ingår i: Advanced Functional Materials. - : John Wiley and Sons Inc. - 1616-301X .- 1616-3028. ; 33:4
-
Tidskriftsartikel (refereegranskat)abstract
- Converting omnipresent environmental energy through the assistance of spontaneous water evaporation is an emerging technology for sustainable energy systems. Developing bio-based hydrovoltaic materials further pushes the sustainability, where wood is a prospect due to its native hydrophilic and anisotropic structure. However, current wood-based water evaporation-assisted power generators are facing the challenge of low power density. Here, an efficient hydrovoltaic wood power generator is reported based on wood cell wall nanoengineering. A highly porous wood with cellulosic network filling the lumen is fabricated through a green, one-step treatment using sodium hydroxide to maximize the wood surface area, introduce chemical functionality, and enhance the cell wall permeability of water. An open-circuit potential of ≈140 mV in deionized water is realized, over ten times higher than native wood. Further tuning the pH difference between wood and water, due to an ion concentration gradient, a potential up to 1 V and a remarkable power output of 1.35 µW cm−2 is achieved. The findings in this study provide a new strategy for efficient wood power generators. © 2022 The Authors.
|
|
| 5. |
- Li, Lengwan, et al.
(författare)
-
Ultrastrong Ionotronic Films Showing Electrochemical Osmotic Actuation
- 2023
-
Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 35:45
-
Tidskriftsartikel (refereegranskat)abstract
- A multifunctional soft material with high ionic and electrical conductivity, combined with high mechanical properties and the ability to change shape can enable bioinspired responsive devices and systems. The incorporation of all these characteristics in a single material is very challenging, as the improvement of one property tends to reduce other properties. Here, a nanocomposite film based on charged, high-aspect-ratio 1D flexible nanocellulose fibrils, and 2D Ti3C2Tx MXene is presented. The self-assembly process results in a stratified structure with the nanoparticles aligned in-plane, providing high ionotronic conductivity and mechanical strength, as well as large water uptake. In hydrogel form with 20 wt% liquid, the electrical conductivity is over 200 S cm−1 and the in-plane tensile strength is close to 100 MPa. This multifunctional performance results from the uniquely layered composite structure at nano- and mesoscales. A new type of electrical soft actuator is assembled where voltage as low as ±1 V resulted in osmotic effects and giant reversible out-of-plane swelling, reaching 85% strain.
|
|
| 6. |
- Ram, Farsa, et al.
(författare)
-
Advanced Applications of Cellulose in Mechanical Energy Harvesting and Sensing
- 2021
-
Ingår i: Trends in Carbohydrate Research. - : Association of Carbohydrate Chemists and Technologists. - 0975-0304. ; 13:4, s. 84-99
-
Tidskriftsartikel (refereegranskat)abstract
- Environmental concerns and depleting fossil resources have led to tremendous research interest in sustainable polymeric materials. Cellulose occupies a unique place among the various polymers that have been widely explored as sustainable alternatives to fossil-derived polymers. It is incredible to see new and exciting developments involving cellulose, a ubiquitous polymer that has been known to humankind for millions of years. Mechanical energy harvesting and sensing is one such emerging application of cellulose. The inherent piezoelectric properties of this polysaccharide and its ability to strengthen the piezoelectric properties of other polymers have captivated a lot of research interest in recent years. This minireview attempts to capture some of the recent developments on cellulose-based piezoelectric materials with a particular focus on nanogenerator device fabrication and characterization. The review is not intended to be comprehensive. It is only an effort to showcase the potential of cellulose as piezoelectric sensors and actuators, mechanical energy harvesters, and as a reinforcing agent for piezoelectric composites.
|
|
| 7. |
- Ram, Farsa, et al.
(författare)
-
FUNCTIONALIZED WOOD COMPOSITES FOR MECHANICAL ENERGY HARVESTING AND VIBRATION SENSING
- 2022
-
Ingår i: ECCM 2022. - : Composite Construction Laboratory (CCLab), Ecole Polytechnique Federale de Lausanne (EPFL). ; , s. 801-806
-
Konferensbidrag (refereegranskat)abstract
- Sustainable energy technologies require the development of sustainable composites using novel methods and materials with a minimal environmental impact. Piezoelectric effect-based mechanical energy harvesting (MEH) and sensing offer great potential as a sustainable technology for low-grade mechanical energy harvesters and self-powered sensors. Herein, we utilize ZnO to functionalize the delignified wood surface for MEH and vibration sensing applications, where wood act as robust support to well adhered piezoelectric ZnO nanoparticles. This surface functionalization strategy is a reasonable substitute for the bulk ZnO films, which offer optimal utilization of active material at relatively low content. The wood/ZnO composite device is utilized for vibration sensing and MEH. The device (25 cm2) resulted in a peak to peak output voltage of ~15 mV and a peak to peak current of ~2.2 nA under the influence of mechanical vibrations from the periodic motion of a linear motor operating at the acceleration of 50 ms-2. The scalable fabrication approach signifies the practical use of wood-based composites for piezoelectric mechanical energy harvesting.
|
|
| 8. |
- Ram, Farsa, et al.
(författare)
-
Functionalized Wood Veneers as Vibration Sensors : Exploring Wood Piezoelectricity and Hierarchical Structure Effects
- 2022
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:10, s. 15805-15813
-
Tidskriftsartikel (refereegranskat)abstract
- Functional wood materials often rely on active additives due to the weak piezoelectric response of wood itself. Here, we chemically modify wood to form functionalized, eco-friendly wood veneer for self-powered vibration sensors. Only the piezoelectricity of the cellulose microfibrils is used, where the drastic improvement comes only from molecular and nanoscale wood structure tuning. Sequential wood modifications (delignification, oxidation, and model fluorination) are performed, and effects on vibration sensing abilities are investigated. Wood veneer piezoelectricity is characterized by the piezoresponse force microscopy mode in atomic force microscopy. Delignification, oxidation, and model fluorination of wood-based sensors provide output voltages of 11.4, 23.2, and 60 mV by facilitating cellulose microfibril deformation. The vibration sensing ability correlates with improved piezoelectricity and increased cellulose deformation, most likely by large, local cell wall bending. This shows that nanostructural wood materials design can tailor the functional properties of wood devices with potential in sustainable nanotechnology.
|
|
| 9. |
- Ram, Farsa, et al.
(författare)
-
Nanocellulose/melanin-based composites for energy, environment, and biological applications
- 2022
-
Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 57:30, s. 14188-14216
-
Tidskriftsartikel (refereegranskat)abstract
- Melanins, a class of brown-black pigments present in many natural sources, exhibit unique physical and chemical properties such as photoprotection, photoconductivity, metal ion chelation, free radical quenching, proton conductivity, and significant antimicrobial properties. These properties could be leveraged in various environmental and energy applications. However, their limited solubility makes them less amenable to processing. Over the last decade, there has been tremendous interest in developing synthetic analogs of melanin that are easy to dissolve and process. Nonetheless, melanins or their synthetic analogs cannot form mechanically robust free-standing films and fibers. This drawback could be partly circumvented by creating composites of melanin with nanocellulose, a nanomaterial derived from cellulosic biomass. Composites of melanins and nanocellulose offer an opportunity to utilize the functional aspects of melanin-like polymers in a mechanically stable nanocellulose network. This review attempts to capture the recent developments on this topic with special emphasis on technologically relevant applications.
|
|
| 10. |
- Ram, Farsa, et al.
(författare)
-
Scalable, efficient piezoelectric wood nanogenerators enabled by wood/ ZnO nanocomposites
- 2022
-
Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 160
-
Tidskriftsartikel (refereegranskat)abstract
- The need for sustainable development creates opportunities for biomass-based materials design toward piezo-electric mechanical energy harvesting. Wood is promising due to its hierarchical, porous structure. Here, piezoelectric nanogenerators (PENGs) were prepared through nanostructure-controlled zinc oxide (ZnO) growth inside the outer wood layers of veneers. Mechanisms for formation of various ZnO nanostructures in wood are analyzed. Controlled morphologies of nanoparticles, nanorods, nanowires, and nanoflakes were realized and characterized by field emission-scanning electron microscopy (FE-SEM) and small angle x-ray scattering (SAXS), allowing tunable piezoelectric output. Nanostructures with higher aspect ratios i.e. nanorods and nanowires resulted in higher voltage during cyclic loading. An optimum voltage of 1.3-1.4 V was obtained with wood/ZnO nanowire or nanorod composites at a force of approximate to 8 N. The current output is in the range of 0.85-11 nA, which could be scaled up to ~130 nA with a larger area device. When mounted in shoe soles, these wood/ZnO PENGs generated 1-4 V from walking/jogging motions. The hydrothermal growth method is scalable, which facilitates practical applications.
|
|
