Energy Harvesting Research Articles

A First-principles Investigation of the Structural, Optoelectronic, Elastic and Thermal properties ofthe p-type Half-metallic Ferromagnetic Perovskites BaFeX3(X = Cl, Br, I)

Abstract The half-metallic nature of the metal halide perovskites BaFeX3 (X=Cl, Br,I) and their physical properties were studied using Spin-polarised Density Functional Theory calculations. For each structure, ferromagnetic, antiferromagnetic and non-magnetic calculation were
performed and the ferromagnetic phase was found to have the lowest energy. The calculated band structures in addition to the electronic density of states confirmed half-metallicity, where the perovskites showed semiconducting nature in the spin up
channel and metallic in spin-down channel. The optical properties are calculated and strong absorption in the UV range was seen and the mechanical properties demonstrated mechanical stability with ductile behaviour for all perovskites. The specific heats (at
constant volume) of all of the studied perovskites levelled off to about 245 JK−1mol−1 at high temperatures. The Seebeck coefficient was also calculated as a function of temperature and found to be positive for all the structures which confirm them to be
p-type materials. These perovskites are therefore suited for thin film fabrication and bulk single crystals for applications such as UV photodetectors and energy harvesting, in addition to spintronics applications.

Mechanical Properties of Cocoon Silk Derivatives for Biomedical Application: A Systematic Review

Background: Despite cocoon silk’s well-known strength, biocompatibility, and hypoallergenic properties, its potential medical applications remain largely unexplored. This review, therefore, is of significance as it evaluates the mechanical properties and clinical potential of cocoon silk, a material with promising applications in biomaterials and tissue engineering. Methods: We conducted a comprehensive systematic review adhering to PRISMA guidelines. Our focus was on the primary outcomes of tensile strength and elongation at break, and the secondary outcomes included other mechanical properties, applications, and complications. Results: Out of the 192 silk-related studies, 9 met the criteria. These studies revealed that cocoon silk derivatives exhibit a wide range of tensile strength, from 0.464 to 483.9 MPa (with a median of 4.27 MPa), and elongation at break, from 2.56% to 946.5% (with a median of 60.0%). Biomedical applications of cocoon silk derivatives span from tissue regeneration (n = 6) to energy harvesting (n = 4). Complications often arose from material fragility in non-optimized derivative components. Conclusions: While cocoon silk shows expansive promise due to its suitable mechanical properties and low complication risk, plenty remains to be discovered. Future research is crucial to fully realizing its vast surgical and biomedical potential.

MPPT Solar Controller: A Theoretical Design and Prototype Development

This paper discusses the theoretical design and ongoing prototype development of a Maximum Power Point Tracking (MPPT) solar controller system aimed at efficient energy harvesting and smart load management. The system is designed to optimize energy extraction from a solar panel using MPPT algorithms, with smart load management for real-time power distribution. The controller incorporates cloud-based monitoring, AI optimization, and a user-friendly interface. The system is expected to deliver robust, efficient, and safe operation under varying environmental conditions

Sustainable Biopolymers in Eco-Friendly Triboelectric Energy Harvesting.

Biopolymer-based triboelectric nanogenerators (B-TENGs) represent an innovative fusion of eco-friendly, sustainable energy-harvesting technology with renewable and environmentally benign biopolymer material. This integration not only introduces novel pathways for advancing green energy solutions but also offers a critical approach to addressing contemporary environmental challenges and fostering sustainable progress. Over the past few years, B-TENGs have seen rapid and remarkable growth in the realm of biopolymers, device architecture, and their applications (e.g., implantable power source, electronic medicine, human anatomical and physiological movements monitoring sensors, etc.). In this review article, the promising developments in harnessing triboelectric biopolymers are encapsulated, enumerate their representative applications, evaluate the pros and cons of these biopolymers, highlight key challenges for future research, and offer strategic recommendations for innovating and realizing advanced B-TENGs.

Engineering Higher-Order Topological Confinement via Acoustic Non-Hermitian Textures.

Higher-order topological insulators are a newly unveiled category of topological materials, distinguished by their exceptional characteristics absent in conventional topological insulators, e.g., 1D hinge states, or zero-dimensional corner states, for instance. Adding attenuating or amplifying components manifest even richer and more intricate non-Hermitian topological properties. While losses, for the most part, come for free, decorating topological systems with the gain counterpart poses significant challenges. Here, a non-Hermitian second-order topological insulator (SOTI) is constructed for a sonic demonstration, by bestowing a cavity-based lattice both with electro-thermoacoustic gain and loss. The inner cavity walls are decorated with electrically biased carbon nanotube films to be able to manipulate spatially and in strength, a non-Hermitian response at will. These measurements demonstrate that this flexibility allows us to design highly unconventional interface and corner confining topologies by decisively engineering gain and loss textures within the unit cell. It is foreseen that the advances may enable new avenues for energy harvesting and fundamental understanding in condensed matter and classical topologicalphysics.

Evaluating the efficacy of lead-free piezoelectric materials in microcantilever based vibration energy harvesters

Abstract The piezoelectric materials have been extensively utilized in various applications, such as sensors, actuators, and energy harvesters. This study evaluates the performance of six lead-free piezoelectric materials- aluminium nitride (AlN), barium titanate (BaTiO3), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), polyvinylidene fluoride (PVDF), and zinc oxide (ZnO) in MEMS-based piezoelectric vibration energy harvesters (PVEHs) using cantilever configurations. Finite element analysis via COMSOL Multiphysics was employed to assess the deflection, voltage, and power outputs of these materials at their resonance frequencies, both with and without proof masses. The results indicate that BaTiO3 and PVDF cantilevers exhibited the highest voltage outputs, reaching 207.14 mV and 202.07 mV, respectively, with AlN also showing comparable performance at 184.72 mV. ZnO-based cantilevers demonstrated the highest power output of 1.35 nW without proof masses and 190.5 nW with proof masses, indicating its potential for high-power applications. The addition of proof masses generally reduced resonant frequencies but enhanced power outputs, like for ZnO. This comprehensive analysis underscores the critical impact of material selection and structural modifications on the efficiency of PVEHs, with BaTiO3, PVDF, and ZnO emerging as the most promising candidates for optimizing energy harvesting devices. This research lays a foundation for further advancements in piezoelectric MEMS technology, aiming for more efficient energy harvesting solutions.

Utilization of Stochastic P-bifurcation for Simultaneous Energy Harvesting and Vibration Suppression: An Experimental Investigation

Abstract This research focuses on the prediction and experimental verification of P-bifurcation as well as the effectiveness in reducing vibrations and harvesting energy with the use of an inertially nonlinear energy harvesting device attached to a single-degree-of-freedom structure subjected to Gaussian broadband base excitation, modeled as white noise. Four experimental scenarios were tested, including three with different resistive loads and one with an open circuit. Frequency domain optimization involved an optimization routine that was designed to minimize the mean squared error in the pendulum velocity's frequency content below two cycles per second while constraining the RMS velocity discrepancy between the simulations and actual experiments to be below 3%. This facilitated accurate predictions of power, vibration suppression, and P-bifurcation. Using the fitted model, an analytically derived P-bifurcation boundary in the noise intensity versus electrical damping plane was presented and experimentally verified. Additionally, power spectral densities for electric power and relative suspended mass velocity were determined for the IPVA system and compared with a top-performing linear system. Results indicated that the monomodal system was the least effective in energy harvesting, while the bimodal and rotational systems significantly enhanced mean and resonant peak power by up to four and two times, respectively. Near the resonant frequency, the peak relative velocity power spectral density decreased by a factor of four, and the mean square relative velocity improved by a factor of two.

Strain-Induced Tunable Enhancement of Piezoelectricity in a Novel Molecular Multiferroic Material.

Multiferroics are appealing because of application potentials in data storage devices, sensors, transducers, and energy harvesters. Molecular multiferroics emerge as a promising alternative to inorganic multiferroics due to flexibility, light weight, low toxicity, solution processing, structural diversity, and chemical tunability. While researches have predominantly focused on perovskite structures, studies on molecular ionic multiferroics remain relatively limited. It is urgent to creatively build a novel platform for studying and developing the coupling and interaction between the stress, electricity, and magnetism. Knowing this, the work focuses on a novel organic-inorganic hybrid multiferroic N-ethyl-N-(fluoromethyl)-N-methylethylammonium tetrabromoferrate (III) showing coexisting magnetic and electric orderings. It undergoes antiferromagnetic, ferroelectric, and ferroelastic transitions. Notably, under a strain of 2.0%, the piezoelectric response increases tenfold, and the coercive field of ferroelectric polarization is reduced by half. The strain-induced enhancement of piezoelectricity is rarely reported in molecular multiferroics. Density functional theory is employed to predict that the mechanism of the large piezoelectric response under strain engineering is related to the cation rotation and phase switching between the stable phase and an energetically competitive metastable phase. This study creates a new paradigm to develop molecular multiferroics and future microelectronic devices for energy conversion.

Development of Turbocharging-Ability Hybrid Nanogenerators Comprising Bipolar PVDF-HFP/MXene Electrospun Composites.

Coupling piezo-active and triboelectric materials has recently emerged as an effective technique for developing high-performance hybrid nanogenerators (HNGs). This is the first paper to report the fabrication of piezo-active poly(vinylidene fluoride-hexafluoropropylene)(PVDF-HFP)/MXene-based hybrid composite fibers through conventional electrospinning. Here, the effect of MXene content (1-5%) on the surface potential and electrical performance of the as-synthesized composites is investigated and optimized. PVDF-HFP/3% MXene (PHM3)/Nylon 12+A-rGo (NY2)-HNG, which contains the best-performing composite (PMH3; containing 3% of MXene), exhibits turbocharging properties (charging a 10 µF capacitor with 16V within 100 s) and can continuously operate low-power electronics. Interestingly, PHM3 (with a negative surface potential) is transformed into PPHM3 (with a positive surface potential of +2190V) via corona poling. This study proposes a new class of HNGs containing frictional layers comprising bipolar PVDF-HFP/3% MXene composites (PHM3/PPHM3-HNG) with an excellent output performance of 297V and 5.1µA that exhibit broad application prospects in energy harvesting.

Fabrication of MoFe2O4/Cr-MOF//activated Carbon Nanocomposite Electrode Material for High Performance Energy Storage and Fast Response for Gluten Detection

Abstract Gluten is a high-energy protein that is present in some grains, such as wheat, rye, and barley. It has a significant impact on the food production processes. In this work, the MoFe2O4/Cr-MOF composite was synthesized using a hydrothermal method. To estimate the electrochemical properties, the MoFe2O4/Cr-MOF composite-based electrode is designed, which shows the specific capacity (Qs) of 1050 Cg-1 at 3 mVs-1 because of the enhancement in redox-active sites and conductivity. The hybrid electrode MoFe2O4/Cr-MOF//AC revealed Qs of 337 Cg-1. In addition, the device demonstrated an exceptional energy density (Ed) of 55 Whkg-1 and a power density (Pd) of 2200 Wkg-1. The device showed capacity retention of 88% and Coulombic efficiency of 96% after 5000 cycles. Furthermore, the MoFe2O4/Cr-MOF composite is utilized for the detection of gliadin. The electrochemical sensor showed an extraordinary sensitivity of 732 µA mM−1 cm−2 against the gluten. The MoFe2O4/Cr-MOF nanocomposite has diverse potential for creating hybrid devices used in applications related to food and energy harvesting.

Enhanced RF Energy Harvesting System Utilizing Piezoelectric Transformer

RF energy harvesting converts ambient signals into electrical power, providing a sustainable energy source. This study demonstrates the use of a piezoelectric transformer for efficient RF energy harvesting. In this work, a piezoelectric transformer (PT) is employed as a high-gain, efficient inverting amplifier to enhance RF wireless energy harvesting. The PT, composed of lead zirconate titanate (PZT), is placed after the receiving loop antenna, with its output connected to an AC-to-DC converter circuit. Maximum harvested power was observed at the PT’s resonance frequency of 50 kHz, with an optimal load of 40 kΩ. The system, comprising the antenna, transformer, and rectifier circuit, continues to resonate at 50 kHz, as confirmed by input impedance measurements, demonstrating stable and effective performance. The overall system efficiency was characterized to be 88%.

Research Progress of Flexible Electronic Devices Based on Electrospun Nanofibers.

Electrospun nanofibers have become an important component in fabricating flexible electronic devices because of their permeability, flexibility, stretchability, and conformability to three-dimensional curved surfaces. This review delves into the advancements in adaptable and flexible electronic devices using electrospun nanofibers as the substrates and explores their diverse and innovative applications. The primary development of key substrates for flexible devices is summarized. After briefly discussing the principle of electrospinning, process parameters that affect electrospinning, and two major electrospinning techniques (i.e., single-fluid electrospinning and multifluid electrospinning), the review shines a spotlight on the recent breakthroughs in multifunctional and stretchable electronic devices that are based on electrospun substrates. These advancements include flexible sensors, flexible energy harvesting and storage devices, flexible accessories for electronic devices, and flexible environmental monitoring devices. In particular, the review outlines the challenges and potential solutions of developing electrospun nanofibers for flexible electronic devices, including overcoming the incompatibility of multiple interfaces, developing 3D microstructure sensor arrays with gradient geometry for various imperceptible on-skin devices, etc. This review may provide a comprehensive understanding of the rational design of application-oriented flexible electronic devices based on electrospun nanofibers.

Optimization algorithm of UAV‐assisted federated learning resources based on wireless energy harvesting

AbstractFederated learning (FL) enhances data privacy and security by enabling multiple terminals to collaboratively train a global model without transferring data to a central location. To tackle the challenges of limited terrestrial communication resources and device energy in FL, a UAV‐assisted federated learning and energy collection resource optimization algorithm is proposed. This algorithm harvests the working energy of FL terminals from radio frequency signals transmitted by the UAV via wireless energy collection. Considering energy causality and limited resources, we formulate a problem aimed at minimizing the completion time of FL training tasks. As this problem is NP‐hard, we initially employ a greedy algorithm to optimize the UAV's position, then decompose it into three sub‐problems: computing resources, power control, and bandwidth allocation. We derive and establish the optimization objective function for computing resources as convex, obtaining the expression for optimal computing resources. The Brent algorithm, based on golden section interpolation, iteratively solves the power distribution sub‐problem, while the Lagrange‐quasi‐Newton algorithm optimizes bandwidth allocation for each user. Simulation results demonstrate that the proposed algorithm effectively reduces training completion time while maintaining training quality.

Nanoarchitecture via Synchronic Stacking of Metallic and Nonmetallic Two-Dimensional Nanosheets for Optimal Light-Driven Ion Transport.

The exceptional selectivity and responsive ion transport in biological channels inspire technology breakthrough in energy, environmental, and resource sectors. However, existing nanofluidic systems with a high photothermal conversion efficiency often exhibit excessive thermal conductivity, which impedes the creation of effective temperature gradients and results in a low ion transport efficiency. In this study, a strategy based on the synchronic stacking of metallic and nonmetallic two-dimensional (2D) nanosheets was presented to construct heterogeneous nanofluidic channels. This specific nanoconfined architecture sustained high temperatures in the illuminated area while maintaining low temperatures in the nonilluminated area, thus obtaining a robust driving force from sunlight for directional ion transport. As a result, our light-responsive ion transport system demonstrated significant potential in solar energy conversion and osmotic energy harvesting, surpassing those of all previously reported nanofluidic systems. Additionally, although it is still at the proof-of-concept stage, it shows great promise in light signal monitoring. This work provides an effective strategy for developing advanced light-responsive ion transport systems and their important applications.

Double effects of mitigating cyanobacterial blooms using modified clay technology: regulation and optimization of the microbial community structure

Harmful algal blooms (HABs) are global hazards under global climate change and eutrophication conditions. Modified clay (MC) method is widely used to control HABs in Asian and American coastal waters. However, little research has been conducted on the underlying mechanisms by which MC controls blooms in freshwater environments. Herein, experiments and bioinformatics analyses were conducted for MC-based control of freshwater blooms in a closed water body with an area of approximately 240 m2 in the Fuchun River, China. Results revealed that the dominant bloom species were Microcystis, and an 87.68–97.01% removal efficiency of whole algal biomass was achieved after 3 h of MC treatment. The weaker zeta potentials of Microcystis species and hydrophilic groups such as O-H and P-O-P in the extracellular polymeric substances (EPS) surrounding Microcystis cells made them easier to be flocculated and removed by MC particles, and the relative abundance of Microcystis decreased to 29.12% and that of Cyanobium increased to 40.97%. Therefore, MC changes the cyanobacterial community structure, which is accompanied by the elimination of Microcystis sp. apical dominance and enhanced competition between Cyanobium and Microcystis in the phytoplankton community, increasing cyanobacterial community diversity. Under MC treatment, residual microorganisms, including cyanobacteria, had a high potential for DNA damage repair and were more likely to survive after being subjected to oxidative stress. In the meanwhile, the abundance of genes involved in genetic information processing, signal transduction, and photosynthesis was decreased indicating that the residual microbiome was week in proliferation and light energy harvesting. Therefore, accompanied with the destruction of Microcystis colonies, MC changes the function of cyanobacteria and phycosphere microbiome, further hindering bloom development. These findings illustrate that MC can regulate and optimize the microbial community structure through which MC controls cyanobacterial blooms in ecosystems.

MXene/NiCu-MOF//AC Nanocomposite Electrode: A Dual-Functional Platform for Energy Storage and Real-Time Monitoring of Monosodium Glutamate Based Sensors

Abstract Monosodium glutamate (MSG), also known as sodium glutamate, is a widely used food additive in commercial foods, and controlling its level is essential for ensuring food safety and quality. For the detection of MSG, the hydrothermal approach is used to synthesize both MXene and NiCu-MOF. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were manipulated to examine the composite morphology, structure, and composition. The MXene/NiCu-MOF electrode displayed an exceptional specific capacity of 277 Cg-1 at a scanning speed of 1.3 mVs-1. The MXene/NiCu-MOF//AC electrode exhibited an exceptional (Cs) of 271.64 Cg-1 at 2 Ag-1 when employed in a supercapattery. The device demonstrated excellent performance, attaining a (Pd) of 1946.21W kg-1 and (Ed) of 37.17 Wh kg-1. Furthermore, MXene/NiCu-MOF//AC demonstrated exceptional capacity retention of 81% after 5,000 cycles in the reliability test. The MSG was utilized as a glassy carbon electrode which was enhanced with gold nanoparticles. The current detection technique implemented NiCu- MOF/MXene as a conductive matrix, with the use of an anti-glutamate antibody. The correlation remained stable from 0.05 to 200 µM detection range. The multipurpose MXene/NiCu-MOF nanocomposite electrode material opens up possibilities for developing novel hybrid devices in energy harvesting.

Defect Engineering with Rational Dopants Modulation for High-Temperature Energy Harvesting in Lead-Free Piezoceramics

HighlightsThe solution limit of manganese ion in BiFeO3–BaTiO3 (BF–BT) was determined by combining multiple advanced characterization methods.The defect engineering associated with fine doping can realize the co-modulation of polarization configuration, iron oxidation state and domain orientation.The BF–BT–0.2Mn piezoelectric energy harvester shows excellent power generation capacity at 250 °C, which is an important breakthrough for lead-free piezoelectric devices.

Energy harvesting from wearable life jackets to assist search and rescue: modeling and design

Energy harvesting from wearable life jackets to assist search and rescue: modeling and design

Breaking dielectric dilemma via polymer functionalized perovskite piezocomposite with large current density output

Organometal halide perovskite (OHP) composites are flexible and easy to synthesize, making them ideal for ambient mechanical energy harvesting. Yet, the output current density from the piezoelectric nanogenerators (PENGs) remains orders of magnitude lower than their ceramic counterparts. In prior composites, high permittivity nanoparticles enhance the dielectric constant (ϵr) but reduce the dielectric strength (Eb). This guides our design: increase the dielectric constant by the high ϵr nanoparticle while enhancing the Eb by optimizing the perovskite structure. Therefore, we chemically functionalize the nanoparticles to suppress their electrically triggered ion migration for an improved piezoelectric response. The polystyrene functionalizes with FAPbBr2I enlarges the grains, homogenizes the halide ions, and maintains their structural integrity inside a polymer. Consequently, the PENG produces a current density of 2.6 µAcm−2N−1. The intercalated electrodes boost the current density to 25 µAcm−2N−1, an order of magnitude enhancement for OHP composites, and higher than ceramic composites.

Wave Energy Potential and the Role of Extreme Events on South America's Coasts. A Regional Frequency Analysis

This study examines wave energy potential and generation capacity from extreme waves along South America's Pacific and Atlantic coasts. Utilizing the Regional Frequency Analysis (RFA) method and the WAVERYS wave reanalysis model, 27 homogeneous regions with distinct wave patterns were identified. There's a notable southward increase in median and average wave heights and energy. Unlike previous studies, this research emphasizes the significant role of extreme wave events, which contribute up to 33 % of the total energy—a critical factor often overlooked in regional energy assessments. In the Pacific, three main zones were delineated, with energy peaks reaching 120 kW/m south of 50°S, while the Atlantic identified two zones with energy values ranging from 10 kW/m to 30 kW/m. Zones between 10°S to 40°S in the Pacific and 30°S to 60°S in the Atlantic stand out as particularly promising for energy harvesting. A comprehensive statistical methodology enabled predictions of wave heights and energy for 50 and 100-year return periods, predominantly utilized generalized Pareto and Gumbel distributions. The study affirms the efficacy of the RFA in improving the understanding of wave dynamics and highlights the necessity of integrating extreme events in energy assessments. This research provides a foundation for advancing wave energy initiatives and coastal risk mitigation in South America.