High Harvesting Research Articles

Nanointerface Insights in PVDF Films with Low Loading of Nitrogen-Doped Carbon Dots for High Energy Density Storage and Harvesting

Nanointerface Insights in PVDF Films with Low Loading of Nitrogen-Doped Carbon Dots for High Energy Density Storage and Harvesting

Dual band angle insensitive metamaterial absorber with MgxCa(0.90−x)Ni0.10Fe2O4 based novel microwave flexible substrate for electromagnetic energy harvesting application

This article presents a metamaterial absorber originated on a flexible substrate of MgxCa(0.90−x)Ni0.10Fe2O4. The MgxCa(0.90−x)Ni0.10Fe2O4 substrate is developed using the sol-gel technique, where X25, X50, and X75 represent 25%, 50%, and 75% of the corresponding material concentration, respectively. The dielectric constant values for X25, X50, and X75 are 2.52, 3.05, and 3.44, with loss tangents of 0.0026, 0.004 25, and 0.0062, respectively. The substrate nanoparticles’ morphology is analyzed using x-ray diffraction, energy dispersive x-ray characterization, and field emission scanning electron microscopy. A metamaterial absorber is then designed on this substrate with a dimension of 16 × 16 mm2. The resonator is comprised of three rings with a square-shaped split outer ring, a square-shaped middle ring, and an innermost arrow-shaped structure. It exhibits absorptance peaks of 99.45% and 99.61% at 4.51 and 7.26 GHz, respectively. Metamaterial and absorber properties are investigated with surface current, electric, and magnetic field analysis. The proposed flexible metamaterial absorber (FMMA) exhibits single negative properties, and it also demonstrates an insensitive response up to 75° for both polarization angle and incident angle variation in transverse electric mode. Furthermore, the FMMA demonstrates exceptionally high energy harvesting (EH) efficiencies of 95.11% and 96.02% at 4.51 and 7.26 GHz, respectively. The efficiency is also investigated for various bending conditions. The small size, lightweight, and flexibility of the structure indicate that MgxCa(0.90−x)Ni0.10Fe2O4 based FMMAs have significant potential for EH applications in the C band.

Mechanism of nitrous oxide emission reduction in constructed wetlands based on plant harvesting management.

The impact of plant harvesting on nitrous oxide (N2O) emission reduction in constructed wetlands (CWs) remains uncertain. This study focused on the Myriophyllum aquaticum wetland treating swine wastewater, with three different plant harvesting frequencies implemented: high harvesting (HF), low harvesting (LF), and no harvesting (CK). Results showed that compared to CK, cumulative N2O emissions decreased by 7.4 % (HF) and 18.5 % (LF), with only LF showing a significant reduction. The primary reductions in N2O emissions occurred during winter and summer, accounting for 26.2 %∼39.7 % and 14.0 %∼49.2 % of the total reductions, respectively. Crucial contributors to mitigating N2O emissions included water redox potential, sediment dissolved organic carbon, and ammonia nitrogen levels. Additionally, increased denitrification gene abundance in harvesting treatments reduced N2O emissions. These findings suggest that low-frequency plant harvesting, particularly in winter and summer, can significantly reduce N2O emissions from CWs.

Compressing slippery surface-assembled amphiphiles for tunable haptic energy harvesters.

A recurring challenge in extracting energy from ambient motion is that devices must maintain high harvesting efficiency and a positive user experience when the interface is undergoing dynamic compression. We show that small amphiphiles can be used to tune friction, haptics, and triboelectric properties by assembling into specific conformations on the surfaces of materials. Molecules that form multiple slip planes under pressure, especially through π-π stacking, produce 80 to 90% lower friction than those that form disordered mesostructures. We propose a scaling framework for their friction reduction properties that accounts for adhesion and contact mechanics. Amphiphile-coated surfaces tend to resist wear and generate distinct tactile perception, with humans preferring more slippery materials. Separately, triboelectric output is enhanced through the use of amphiphiles with high electron affinity. Because device adoption is tied to both friction reduction and electron-withdrawing potential, molecules that self-organize into slippery planes under pressure represent a facile way to advance the development of haptic power harvesters at scale.

Theoretical Analysis into the impact of π-spacers on Triphenylamine based Organic Sensitizers for Dye Sensitized Solar Cells (DSSCs)

In the present study, thirteen triphenylamine-based organic dye sensitizers with donor-π-acceptor patterns were created for utilization in dye sensitized solar cells (DSSCs). Theoretical computations such as DFT and TDDFT were employed to analyse the molecular structure of the dyes. Optimization was attained using the DFT/B3LYP approach with the 6-311++G (d,p) basis set to investigate structural and spectroscopic parameters. This study deals with the effect of different π-spacers. The electrochemical characteristics, electronic absorption spectra, energy levels, injection energy, light harvesting efficiency (LHE), frontier molecular orbitals, and dye generation energy were examined. All the created dyes are suitable for DSSC applications. The parameters such as low bandgap (2.30 eV), high light harvesting efficiency (0.972), strong oscillator strength, broad absorption spectrum and high electron injection energy made the dye P6 the best-performing one.

Performance assessment of Savonius wind turbine: Impact of the cylindrical deflectors with natural shapes

Savonius wind turbine, with various advantage features, is expanding its application for energy harvesting in urban and offshore environments. However, the drawback of this turbine relies on its relatively low aerodynamic efficiency. This study aims to enhance the Savonius wind turbine's aerodynamic performance to expand its effective application in urban areas and reduce offshore wind energy costs by using multiple cylindrical deflectors with natural geometry, changing from square to circular shapes. Results from the sequence of two-dimensional (2D) unsteady computational fluid dynamics (CFD) simulations show various performances gained depending on the deflector shapes. The highest power coefficient, with an increment of up to 133% over the turbine without the deflectors without the complex structure and the requirement of the rotated cylinder, is attained with the square cylindrical one at different wind conditions. The insight flow analysis reveals that the high jet flow formed between the turbine and the deflectors is the physical reason behind such improvement, through adding more positive pressure force on the advancing blade while increasing the recovery pressure on the concave side of the returning one. The results suppose the significance of the present study with a simple wind turbine-deflector configuration for high energy harvesting in urban and offshore environments with effective costs.

Modular arborized fog harvesting device with coordinated mechanism of capture and transport

With global water scarcity a growing problem, fog harvesting technology has emerged as an effective solution. Industrial development and population growth have exacerbated the need for efficient, dismantlable, and assembled fog harvesting devices, as well as the requirement to optimize the droplet capture-transport relationship. In this study, a novel modular bionic 3D tree-like structure for fog harvesting system (3D-TSFHS) was developed to achieve rapid droplet transport by means of Nepenthes-inspired superslip leaves (SSLs). In addition, aluminum (Al) cones with superhydrophilic and superhydrophobic (SHL-SHB) patterns were prepared to enhance the droplet capture efficiency by drawing on the special wettability and structural features of various plants and animals such as cactus, spider silk, desert beetles, lizards and camphor leaves. This artificial design significantly enhances the overall capture and transport relationship. The resulting embedded superslip leaves Al cone fog harvesting (E-SLAC-FH) dramatically improves the fog harvesting efficiency and exhibits excellent durability. Assembling this fog harvesting into a 3D-TSFHS achieves a high fog harvesting efficiency of 0.462 g∙cm−2∙min−1. The system's modular design and its exceptional durability ensure its potential for a wide range of applications in a variety of real-world scenarios.

Computational Studies of the Optoelectronic and Charge Transport Properties of Porphyrin and Corrole‐Based Molecules

ABSTRACTThe structural, optoelectronic and charge transport properties of porphyrin and its analogues are investigated using the density functional theoretical methods. Most of the above molecules absorb in visible region with high light harvesting efficiency. The small energy gap between the frontier molecular orbitals (FMOs) suggests that porphyrin and its derivatives can be used in organic semiconductors. Electronic properties such as ionization potential, electron affinity, reorganization energy and the charge transfer integral are calculated to obtain their charge transport properties. It is revealed that porphyrin, porphyrazine and phthalocyanine act as hole transporters, whereas corrole and corrolazine act as electron transporters.

Self-powered wireless sensing system with cylindrical high voltage side electric field energy harvesting by discharge circuit

To warn of overcurrent heating, temperature wireless sensor node (WSN) need to be deployed on the overhead lines of the power grid. The sustainable power supply of WSN is difficult. Using the electric field energy around the transmission line to power the sensor has the advantages of stability, reliability and sustainability, but the electric field energy harvesting (EFEH) power need to be improved. This paper studies the principle of energy harvesting by displacement current and discharge method, and analyzes the influencing factors of the output power of the EFEH unit. The power improvement method of the EFEH unit is proposed by improving the coupling capacitor and the energy storage capacity discharge voltage. The relationship between the structural parameters of energy cylinder and induced potential and coupling capacitance is explored by COMSOL simulation software. A low-cost, self-driven and adjustable high voltage undervoltage lock (UVLO) circuit is proposed. A 10 kV high voltage generation platform is built in the laboratory, and the wireless temperature and humidity sensor is self-powered by the EFEH with power of 2.04 mW. This research has important theoretical and application value for the high voltage side EFEH powered WSN.

Industrial production of asymmetric wettability patterned fabric for efficient atmospheric water harvesting

While harvesting water from the atmosphere is considered as a promising technology to address the increasing issue of water scarcity, its wide applications are still limited by the difficulty in mass production of water harvesting materials. Here, an industrial-producible asymmetric wettability patterned fabric (AWPF) with high water harvesting capacity is developed using a continuous and low-cost weaving technology. Four textile patterns are developed for high-efficiency atmospheric water harvesting. The alternating patterned surface in AWPF is constructed with hydrophilic bumps and hydrophobic grooves using one set of green fluorine-free superhydrophobic polyester warp yarns and two sets of superhydrophobic polyester/hydrophilic viscose weft yarns. We optimized the water collection performance of the single-sided AWPF by spraying co-MBAA-DVB superhydrophobic material on the back of the AWPF to construct a wetting gradient, that is, double-sided AWPF. The double-sided AWPF shows a strong water harvesting capacity of 2840.2 mg·6h−1·cm−2, which increased the water harvesting efficiency by 43.2 % compared with the unoptimized single-sided AWPF. To reduce the pressure drop, 6 mm wide the double-sided AWPF was designed, resulting in a water harvesting capacity that is 1.23 times higher than that of without cutting. This advanced industrialized weaving technology with an asymmetric fabric structure design holds great potential for substantial water harvesting.

Performance Analysis and Operation Parameter Optimization of Shaker-Type Harvesting for Camellia Fruits

This study aims to address the challenges of achieving a high harvesting rate and low flower bud damage rate during the harvesting of camellia fruits. To this end, a dynamic model of the camellia osmantha tree and a self-developed shaker-type harvesting machine were used as research subjects. The first 24 natural frequencies and mode shapes of the camellia tree were solved using the finite element method, and the effects of vibration frequency, excitation position, and vibration duration on the harvesting rate and flower bud damage rate were quantitatively analyzed through an orthogonal experiment. The numerical analysis results indicate that the camellia tree exhibits good response characteristics at vibration frequencies of 10–15.5 Hz and 38.5 Hz. The three-factors orthogonal experiment figured out that the optimal operational parameters for shaker-type harvesting were determined to be a vibration duration of 30 s, a motor output frequency of 12.5 Hz, and a gripping position height of 50 to 60 cm above the ground. Meanwhile, under these operational parameters, the harvesting efficiency reached 96.97%, while the flower bud damage rate was only 6%.

Energy harvesting properties for potassium-sodium niobate piezoceramics through synergistic effect of phase structure and texturing engineering

In order to address the energy dilemma and meet environmental protection requirements, it is an urgent need to develop lead-free piezoelectric energy harvesters (PEHs). However, the low output power density has seriously hindered the application of lead-free piezoceramics as high efficiency energy harvesters. To solve above question, the combination of phase structure regulation and texturing technique in the K0.5Na0.5NbO3-xBi0.5Na0.5ZrO3-0.5%wtBiFeO3 (KNN-xBNZ) ceramics was adopted in this work. Because of both the Rhombohedral-Orthorhombic-Tetragonal (R-O-T) multiphases coexistence and texturing engineering, an ultrahigh piezoelectric activity quality factor d33×g33 ∼ 18324 × 10−15 m2 N−1 was achieved in the textured KNN-0.05BNZ (T-KNN-0.05BNZ) ceramics, which is about third times higher than that of random KNN-0.05BNZ (R-KNN-0.05BNZ) (d33×g33 ∼ 6672 × 10−15 m2 N−1) ones. A high output power of ∼0.32 mW was also obtained in the T-KNN-0.05BNZ ceramics by cantilever beam-based energy harvester devices under the resonance frequency of 75 Hz and matched RL of 1.2 MΩ, suggesting that the T-KNN-0.05BNZ ceramics have a great potential for application in the PEHs devices. This result also reveals that the combination of phase structure regulation and texturing technique is an effective way to achieved a high energy harvesting performances.

Optimization of the marine microalgae Nannochloropsis oculata harvesting by flocculation: Effects on biomass quality and residual medium reuse for a new cycle

ABSTRACT Flocculation using natural plant-based biopolymers from Moringa oleifera seeds and Acacia mearnsii flocculant as Tanfloc® (TSG) has emerged as an efficient strategy for microalgae biomass harvesting. This study optimized the recovery process of Nannochloropsis oculata by varying flocculant concentration, sedimentation time, and culture pH. Results revealed that 1.2 mg.L−1 of TSG at pH 8.9 achieved optimal conditions, although TSG proved effective across different pH ranges. Alkaline flocculation (ALK) also enhanced microalgae harvesting, yielding a high harvesting efficiency (>96%) within 30 minutes of sedimentation. Both methods achieved a concentration factor exceeding 20. However, the use of ALK resulted in reduced lipid and carbohydrate content compared to the control condition. Carotenoid levels showed no significant difference. TSG influenced lipid extraction but not fatty acid quality or carbohydrate extraction. Importantly, the residual medium from TSG flocculation could sustain subsequent cultivation cycles without nutrient supplementation, presenting a cost-effective solution for microalgae cultivation and harvesting.

High performance hybrid omnidirectional wind energy harvester based on flutter for wireless sensing and hydrogen production applications

Wind energy harvesters (WEHs) based on wind–induced vibration (WIV) attract increasing attention as the power sources of wireless sensor nodes. The wind direction in natural environments usually changes over time, therefore, it is of significance to develop omnidirectional wind energy harvesters (OWEHs). This paper presents a triboelectric–electromagnetic–piezoelectric hybrid OWEH based on flutter. The secondary collision is introduced into the harvester to improve the electricity produced through triboelectric effect. The efficient electromagnetic electromechanical conversion is realized using planar coils and two magnets with the same magnetic poles facing each other. Experiments are conducted to optimize the prototype and evaluate its performance. The optimized prototype has a wide wind speed range of 3.6–20 m/s and a wind direction range of 0°-360° in the specified plane. The maximum total average output power at 20 m/s is 6.84 mW, respectively. A wireless sensor node power by the prototype measures and sends out the humidity and temperature with a time interval of 2.02–2.43 seconds at 5.3 m/s. A water electrolysis hydrogen production system powered by the prototype produces about 33.8 μL hydrogen per minute at 20 m/s. The high output power, wide speed range, and wide wind direction range of the proposed harvester greatly expand the application scenarios of WIV WEHs.

Separating, purifying and decoding elastic waves by mimicking a cochlea on a thin plate

A human cochlea is capable of continuously separating and amplifying sound of different frequencies to specific positions from 20 to 20,000 Hz, which makes it a high-resolution living sensor. The realization of cochlea-like structure for elastic waves in solids offers a highly desirable functionality on high throughput mechanical energy harvesting and sensing, but remains a challenging topic owing to narrow band and intricate configuration. Here we propose and demonstrate a generic framework of elastic cochlea on a thin plate, enabled by a pair of compact metafence layers. It is experimentally realized to harvest and separate flexural waves in quite a wide frequency range from 5.8 to 21.8 kHz, together with a continuous energy amplification exceeding one magnitude order. An enhanced mode, characterized by a near zero group velocity at a tailored cutoff width, is uncovered to illustrate the filtering and amplification physics. Moreover, complex information demultiplexing and undistorted decoding are further realized by harnessing the high-Q signal sensing and purification. The proposed prototype may stimulate substantial applications on information processing, non-destructive evaluation and other wave regulation scenarios.

Effects of light color on growth, nutrient uptake, and harvesting of the indigenous strain of Chlorococcum sp.

Chlorococcum sp. is robust and has dominant growth in aquatic habitats, making it a promising bioresource. This study investigates the batch-wise cultivation and harvesting of Chlorococcum sp. in a standard medium under various lights, followed by biomass harvesting using FeCl3 as a coagulant. The findings highlight the significant impact of light color on growth and nutrient uptake. Specifically, red and blue light promotes growth, followed by white and violet. Following successful cultivation, the coagulation process underwent optimization, determining the optimal dose for harvesting at different cell concentrations (700 mg/L for 3.6 × 106 cells/mL, 600 mg/L for 3.3 × 106 cells/mL, 500 mg/L for 3.2 × 106 cells/mL, and 400 mg/L for 3.0 × 106 cells/mL), each exhibiting high harvesting efficiency. These findings not only advance microalgae cultivation practices but also provide valuable insights into the effective recovery of biomass, potentially expanding the applications of microalgae in various biotechnological fields.

Surface patterned polyvinyl alcohol/CNT hydrogels for sustained solar powered high concentration brine desalination and salt harvesting

Solar-driven interfacial evaporation is an attractive way to achieve water purification. However, high water evaporation rates often result in the precipitation of salt crystals on the surface of the evaporator leading to decay of the evaporation efficiency over time, which makes it difficult to balance high water evaporation rates with salt resistance. Herein, an anisotropic polyvinyl alcohol/CNT hydrogel is constructed by directional freezing and surface patterning. The polymer backbone formed by the polyvinyl alcohol chains interacts with the water clusters to reduce the evaporation enthalpy of water and the absorbed water can be released by squeezing the hydrogels due to the micron-sized vertically aligned pores. More importantly, by designing the structure of the hydrogels surface, the gas–liquid interface of the evaporators can be increased while the growth direction of the salt crystals can be controlled. As a result, the water evaporation rate can be increased from 3.26 kg m−2 h−1 to 3.69 kg m−2 h−1 under one sun irradiation through surface patterning. After 50 h of continuous operation in 10 wt% NaCl solution under one sun irradiation, the water evaporation rate gradually increases and a large amount of salt collection is collected, which proves its satisfactory salt resistance.

Trapping Ions to Enhance High-Field Energy Harvesting Performance by Filling Polar Macromolecular Dielectrics.

In the quest for sustainable and renewable energy sources, researchers and engineers have explored innovative technologies to harvest energy from various environmental sources. Dielectric elastomer generators (DEGs) with high energy harvesting performance have been proven to be promising energy collectors, but achieving a high dielectric constant (ε') and low electrical conductivity (EC) under high electric fields of dielectric elastomer (DE) simultaneously is a struggle, which poses significant challenges. In this study, high-content carboxyl group-grafted liquid polybutadiene (HCPB) is synthesized and then adopted as an organic dielectric filler to blend and cocross-link with a butadiene rubber (BR) matrix to prepare DE composites with high energy harvesting performance. The introduction of carboxyl groups enhances polarization while trapping free Al3+ in the matrix, which revolutionarily achieves a significant increase in ε' under extremely low EC. Ultimately, the contradiction between increased ε' and decreased EC under high electric fields is reconciled, resulting in a 30 HCPB/BR composite with high energy density (w = 91.9 mJ/cm3) and fine power conversion efficiency (PCE = 24.1%). This advancement paves the way for the development of HCPB/BR composite-based DEGs with enhanced ε' and energy harvesting performance.

Design, optimization and operation of a high power thermomagnetic harvester

Converting low temperature waste heat to electricity is vital for the green transition. Here we present how to design and optimize a thermomagnetic energy harvester that can convert a stream of waste heat to electricity through Faradays law. In optimizing the design in the traditional figure-of-eight shape, we determine the ideal size of the magnet and the beds of magnetic material using a numerical model given an overall volume constraint for each of the thermomagnetic volumes of 20 cm3. The magnet is determined to ideally be 5×5×1.25 cm, the beds should have a height of 1.09 cm and contain about 120 g of Gd spheres, and we use coils with a wire diameter of 1.8 mm and 156 windings in each coil. Following the design study, the system is realized using off-the-shelf components and tested as a function of flow rate, frequency of operation and temperature span. At a temperature span of 40 °C and a hot side temperature of 40 °C, the device produces 9 mW of power at a flow rate of 1.4 L/min.

An Efficient MnO2 Photocathode with an Excellent SnO2 Electron Transport Layer for Photo-Accelerated Zinc Ion Batteries.

Photo-accelerated rechargeable batteries play a crucial role in fully utilizing solar energy, but it is still a challenge to fabricate dual-functional photoelectrodes with simultaneous high solar energy harvesting and storage. This work reports an innovative photo-accelerated zinc-ion battery (PAZIB) featuring a photocathode with a SnO2@MnO2 heterojunction. The design ingeniously combines the excellent electronic conductivity of SnO2 with the high energy storage and light absorption capacities of MnO2. The capacity of the SnO2@MnO2-based PAZIB is ≈598mAh g-1 with a high photo-conversion efficiency of 1.2% under illumination at 0.1 A g-1, which is superior to that of most reported MnO2-based ZIB. The boosting performance is attributed to the synergistic effect of enhanced photogenerated carrier separation efficiency, improved conductivity, and promoted charge transfer by the SnO2@MnO2 heterojunction, which is confirmed by systematic experiments and theoretical simulations. This work provides valuable insights into the development of dual-function photocathodes for effective solar energy utilization.