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Electric-field energy harvesters (EFEHs) have emerged as a promising technology for harnessing the electric field surrounding energized environments. Current research indicates that EFEHs are closely associated with Tribo-Electric Nano-Generators (TENGs). However, the performance of TENGs in energized environments remains unclear. This work aims to evaluate the performance of TENGs in electric-field energy harvesting applications. For this purpose, TENGs of different sizes, operating in single-electrode mode were conceptualized, assembled, and experimentally tested. Each TENG was mounted on a 1.5 HP single-phase induction motor, operating at nominal parameters of 8 A, 230 V, and 50 Hz. In addition, the contact layer was mounted on a linear motor to control kinematic stimuli. The TENGs successfully induced electric fields and provided satisfactory performance to collect electrostatic charges in fairly variable electric fields. Experimental findings disclosed an approximate increase in energy collection ranging from 1.51% to 10.49% when utilizing TENGs compared to simple EFEHs. The observed correlation between power density and electric field highlights TENGs as a more efficient energy source in electrified environments compared to EFEHs, thereby contributing to the ongoing research objectives of the authors.

Energy harvesting textiles have emerged as a promising solution to sustainably power wearable electronics. Textile-based solar cells (SCs) interconnected with on-body electronics have emerged to meet such needs. These technologies are lightweight, flexible, and easy to transport while leveraging the abundant natural sunlight in an eco-friendly way. In this Review, we comprehensively explore the working mechanisms, diverse types, and advanced fabrication strategies of photovoltaic textiles. Furthermore, we provide a detailed analysis of the recent progress made in various types of photovoltaic textiles, emphasizing their electrochemical performance. The focal point of this review centers on smart photovoltaic textiles for wearable electronic applications. Finally, we offer insights and perspectives on potential solutions to overcome the existing limitations of textile-based photovoltaics to promote their industrial commercialization.

There is always considerable inconsistency between the input energy and the amount of the energy required for the load in piezoelectric transducers (PZTs) energy harvesting interface circuits that often degrades the harvesting performance of most of them. Multiple piezoelectric transducers (multi‐PZTs) vibration scavenging may address this issue by enhancing input power and, consequently, environmental adaptability and reliability. The proposed interface circuit may extract energy from a PZT array regardless of each PZT amplitude, frequency, or phase, even under dynamic or heavy load circumstances. The circuit is thoroughly simulated by LTSpice software and evaluated by post‐simulation calculations and discussions. The simulation findings demonstrate that the proposed self‐powered (SP) SECE‐based multi‐PZT EH interface circuit, named MI‐SP‐SECE, can extract a peak power of 12.8 µW from three PZTs in the provided actual scenario at a dynamic load regime with a simulated excitation of 1.5 g and 50 Hz. The proposed circuit's energy integration and harvesting efficiencies are 75% and 85%, respectively. It can achieve a power enhancement of 2.8× relative to a multi‐input full‐bridge rectifier. In addition, the proposed circuit is scalable effectively because it requires just one inductor component. [ABSTRACT FROM AUTHOR]

With burgeoning considerations over energy issues and carbon emissions, energy harvesting devices such as triboelectric nanogenerators (TENGs) are developed to provide renewable and sustainable power. Enhancing electric output and other properties of TENGs during operation is the focus of research. Herein, two species (Nb2S2C and Ta2S2C) of a new family of 2D materials, Transition Metal Carbo‐Chalcogenides (TMCCs), are first employed to develop TENGs with doping into Polydimethylsiloxane (PDMS). Compared with control samples, these two TMCC‐based TENGs exhibit higher electric properties owing to the enhanced permittivity of PDMS composite, and the best performance is achieved at a concentration of 3 wt. ‰ with open circuit voltage (Voc) of 112 V, short circuit current (Isc) of 8.6 µA and charge transfer (Qsc) of 175 nC for Nb2S2C based TENG, and Voc of 127 V, Isc of 9.6 µA, and Qsc of 230 nC for Ta2S2C based TENGs. These two TENGs show a maximum power density of 1360 and 911 mW m−2 respectively. Moreover, the tribology performance is also evaluated with the same materials, revealing that the Ta2S2C/PDMS composite as the electronegative material presented a lower coefficient of friction (COF) than the Nb2S2C/PDMS composite. Their applications for energy harvesting and self‐powered sensing are also demonstrated. [ABSTRACT FROM AUTHOR]

In the present work, flexible Potassium Sodium Niobate - Polyvinyledene Fluoride (KNN-PVDF) composite sheets have been developed and utilized for the realization of a highly efficient pyroelectric energy harvester. KNN-PVDF composite sheets with varying the weight % of KNN (10–50 %) have been synthesized using solution casting method. The influence of KNN (Potassium Sodium Niobate) on the structural, morphological, and dielectric properties of PVDF has been investigated. The highest value of pyroelectric coefficient of 14.7 x 10 −4 Cm −2K−1 has been obtained for the flexible sheets of 30 % KNN-PVDF composite with change in temperature. It has been also observed from the ferroelectric studies that a high value of saturation polarization of 1.44 μC/cm2 is obtained at the applied bias of 5 V and 50 Hz frequency due to the presence of 30 % KNN in the KNN-PVDF composite sheets. The obtained results show the potential application of non-toxic, lead free KNN-PVDF composite sheets for thermal energy harvesting applications utilizing pyroelectric effect. [ABSTRACT FROM AUTHOR]

The global focus on electromagnetic interference and pollution is undeniable. To counter these challenges, high-performance microwave-absorbing materials (MAMs), typically composed of dielectric and magnetic components, offer effective solutions by ensuring favorable impedance matching. Leveraging these MAMs has proven beneficial across various sectors, including 5G technology, information security, energy harvesting, diminished radar cross-section, and advancements in military applications. We successfully synthesized composites of La 1.5 Sr 0.5 NiO 4 (LSNO) and SrFe 12 O 19 (SrM) composites through ball milling and heat treatment. With the escalation of SrM weight percentage in the composites, noticeable alteration in structural, morphological, and static magnetic characteristics was ensured. Moreover, the amalgamation of these components bolstered the EM properties, consequently yielding exceptional microwave absorption capabilities in the composites. The composites with 40, 60, and 80 wt% of SrM (named S4, S6, and S8) exhibited excellent microwave absorption performance with an absorption rate of over 99.9 % for a thin thickness. The S4 and S8 composites attained reflection loss (RL) values of −34.75 dB and −36.93 dB, with 2.0 and 1.6 mm thicknesses, respectively. Meanwhile, the S6 composite achieved an RL value of −44.24 dB with a thickness of 1.9 mm. These composites' outstanding microwave absorption performance can be attributed to their significant magnetic loss, remarkable dielectric loss, and synergistic effects. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surfaces (RISs) have emerged as a groundbreaking technology, revolutionizing wireless networks with enhanced spectrum and energy efficiency (EE). When integrated with drones, the combination offers ubiquitous deployment services in communication‐constrained areas. However, the limited battery life of drones hampers their performance. To address this, we introduce an innovative energy harvesting (EH), that is, EH‐RIS. EH‐RIS strategically divides passive reflection arrays across geometric space, improving EH and information transformation (IT). Employing a meticulous, exhaustive search algorithm, the resources of the drone‐RIS system are dynamically allocated across time and space to maximize harvested energy while ensuring optimal communication quality. Deep reinforcement learning (DRL) is employed to investigate drone‐RIS performance by intelligently allocating resources for EH and signal reflection. The results demonstrate the effectiveness of the DRL‐based EH‐RIS simultaneous wireless information and power transfer (SWIPT) system, demonstrating enhanced drone‐RIS spectrum‐efficient communication capabilities. Our investigation is summarized in unleashing potential, which shows how DRL and EH‐RIS work together to optimize drone‐RIS for next‐generation wireless networks. [ABSTRACT FROM AUTHOR]

In response to the low operating speed and poor stability of energy harvesting systems in smart grids, an energy harvesting optimization method based on improved convolutional neural networks and digital twin technology is proposed in the experiment. Firstly, a smart grid data transmission framework integrating digital twin technology is proposed. A digital twin mapping method based on time, data, and topology structure is used to realize the digital twin mapping at the device level of power grid. Through data synchronization and interaction between the physical power grid and the digital twin model, the operational efficiency and reliability of the power grid are improved. Then, the classical convolutional neural network and attention mechanism are used to comprehensively analyze the physical topology data in the smart grid energy acquisition system. The improved lightweight target detection model is combined to monitor the equipment status of the smart grid and extract key features. Simultaneously utilizing convolutional attention mechanism to dynamically adjust the feature weights of channels or spaces, completing the preprocessing of energy harvesting data. Finally, combined with energy harvesting and power grid switching system, the process of energy harvesting and power grid operation are optimized together. On the training and validation sets, when the channels exceeded 60, the proposed method achieved a system energy efficiency of 55% during operation. The system energy efficiency of the other three comparative algorithms was all less than 40%. In practical applications, as the energy transfer loss increased to 1.0, the system throughput increased to 50 bits. The electricity needs of different users were met, and the difference between power allocation and optimal power allocation was small, which was very reasonable. This proves that the research has effectively optimized the energy harvesting system in the smart grid, improving the efficiency and reliability of the system in practical applications of the smart grid. At the same time, in the increasingly severe energy problem, this system can further provide technical references for the utilization of renewable energy and help achieve the goal of sustainable energy. [ABSTRACT FROM AUTHOR]

Polymer-based ferroelectric composites, particularly those containing Poly (vinylidene fluoride) (PVDF), have emerged as preferred materials for flexible electronics and sensors owing to their excellent electro-mechanical attributes and ease of fabrication. The efficacy of PVDF composites is significantly influenced by the fillers and the proportion of the β-phase present. This research details the synthesis of La 0.7 Ba 0.3 MnO 3 (LBMO) particles via solid-state reaction, surface-functionalized with acetic acid, and subsequently introduced as nucleating agents into Poly (vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) to fabricate LBMO/P(VDF-HFP) composite membranes. The LBMO fillers before modification significantly increased the β-phase content from 32.7 % to 87.8 % in 5 wt% unmodified LBMO/P(VDF-HFP) membranes. After modification, the hydroxyl groups attached to acetic acid-modified LBMO form hydrogen bonds with -CF 2 groups in P(VDF-HFP), inducing the formation of the β phase while enhancing macroscopic polarization and piezoelectricity. At a 7.5 wt% acetate-modified LBMO doping level, the composite membrane exhibits a β-phase content of 64.5 %, but concurrently enhancing the film's dielectric properties. At 103 Hz, the dielectric constant of 5 wt% modified LBMO/P(VDF-HFP) membrane increases to 24.8, with a minimal rise in dielectric loss from 0.0293 to 0.0314. Moreover, under a 10 N compressive load at 1 Hz, the 5 wt% modified LBMO/P(VDF-HFP) composite achieves an open-circuit voltage of 4.3 V. These improved dielectric and piezoelectric properties indicate the composite's suitability for energy harvesting applications. [ABSTRACT FROM AUTHOR]

A thermoelectric generator (TEG) is a semiconductor-based device that can exhibit a flow of electric current through the external circuit if the sides of the TEG are subjected to a temperature difference caused by a heat source. The terminal voltage and the TEG's internal resistance are altered depending on the temperature difference. Therefore, a suitable power electronic converter with a maximum power point tracking (MPPT) feature is required to harvest maximum power from the TEG and store the harvested energy in a battery-based energy storage system. This paper investigates a novel energy harvesting methodology from TEG using a series compensated buck-boost converter (SCBBC). MPPT has also been implemented using a sliding mode controller (SMC). A mathematical model of a TEG source has been developed in MATLAB-Simulink and tested with generic boost converter (GBC) and SCBBC for their dynamic performances during battery charging. The efficiency of conversion is found to be higher for SCBBC, at 97.87%. An experimental prototype has been developed with SCBBC and tested for two configurations, viz high voltage and low current configuration. The former configuration exhibits an efficiency of 86.3%, while the latter has an efficiency of 83%. The results indicate that SCBBC, along with SMC, opens up new efficient prospects for harvesting waste heat energy using TEGs. [ABSTRACT FROM AUTHOR]

Integrating energy storage and harvesting devices have been major challenges and significant needs of the time for upcoming energy applications. Photosupercapacitors are combined solar cell-supercapacitor devices which can provide next-generation portable powerpacks. Owing to advantages like economic and environmental friendliness, dye-sensitized solar cells (DSSCs) offer vast potential for being integrated with energy accumulation devices like supercapacitors. Over the past few years, various types of harvesting cum storage power devices combining DSSCs and supercapacitors have been reported. Over time the devices have improved in both performance and stability providing a broad outlook to possible future advancements including commercialization. We still have many challenges that are yet to be resolved in order to take these powerpacks to the next level of applications in portable and wearable electronics and communication devices. In this context, a detailed analysis and comparison of already reported photo-powered integrated supercapacitors based on DSSCs would give further insights into future advancements. In this review, we have discussed the development of photosupercapacitors, their fabrication strategies, and different materials used as counter electrodes, electrolytes, and dye sensitizers. [ABSTRACT FROM AUTHOR]

The integration of energy harvesting techniques has the potential to significantly prolong target monitoring in wireless sensor networks (WSNs). However, the stochastic nature of hybrid solar-wind energy arrivals poses a significant challenge to optimizing energy utilization for target coverage. To address this issue, we propose a dynamic and distributed node scheduling algorithm based on Lyapunov optimization for hybrid energy-harvesting WSNs (HEH-WSNs). By formulating the maximum long-term average coverage utility subject to peak power constraints, we utilize Lyapunov optimization theory to develop a dynamic potential game framework for target coverage optimization in HEH-WSNs. The proposed distributed dynamic target-coverage node scheduling algorithm (DTNSA) is then derived from the potential game. We present a comprehensive performance analysis of the distributed implementation and evaluate its efficiency through extensive simulations. The results demonstrate that in two distinct scenarios, specifically with different numbers of sensor nodes and target nodes, the average coverage utility of our proposed DTNSA exceeds that of existing algorithms by 10.5 % and 11.2 % , respectively. The performance of the average number of active sensor nodes decreased by 13.2 % and 16.4 % compared to existing algorithms, while the average coverage redundancy decreased by 23.2 % and 21.6 % relative to existing algorithms. Furthermore, our algorithm adapts effectively to dynamic changes in hybrid harvested energy and exhibits lower computational complexity compared to existing target coverage algorithms. [ABSTRACT FROM AUTHOR]

The present research focuses on the electrical properties of lead-free piezoceramics (0.985- x)(K 0.485 Na 0.485 Li 0.03)(Nb 0.96 Sb 0.04)O 3 -0.015(Bi 0.5 Na 0.5)ZrO 3 - x SnO 2 (KNNLS-BNZ- x SnO 2 , x = 0.003, 0.006, 0.009, 0.012, and 0.015). This study examines the influence of varying SnO 2 doping levels on the microstructure and piezoelectric properties of the ceramics. All the ceramics prepared demonstrate pure perovskite structure without any secondary phases. The Rietveld refinement analysis of XRD data reveals the existence of multiphase evolution around room temperature. The tetragonality (c/a) and cell volume of the ceramics tend to rise with an increase in Sn4+ content, potentially leading to improved ferroelectric characteristics. The optimum values obtained were Curie temperature (T c) = 395 oC, remnant polarization (P r) = 21.07 μC/cm2, piezoelectric coefficient (d 33)=357 pC/N, piezoelectric voltage constant (g 33) = 24 × 10−3 Vm/N, and figure of merit (FOM off) = 10.34 pm2/N, corresponding to the ceramic doped with x = 0.012 SnO 2. The findings indicate that an optimal amount of Sn4+ in the host composition KNNLS-BNZ improves piezoelectric properties by constructing an R-O-T phase boundary near room temperature. This study suggests that the ceramic with x = 0.012 SnO 2 exhibits a favorably high T c coupled with an exceptional energy harvesting capability, making it a suitable candidate for energy harvesting applications. [ABSTRACT FROM AUTHOR]

Solar energy harvesting and storage are essential in the future mix of renewable energy technologies. Hierarchical coral‐structured coatings have been shown to yield high solar absorptance in concentrating solar thermal (CST) systems. However, interfacial delamination and scalability challenges owing to material complexity pose significant hurdles for the widespread industrial adoption of these hierarchical CST coatings. Here, a coral‐structured coating is proposed whose black pigments are strongly bonded by titania, which is a material that mitigates interfacial delamination. Importantly, this coating follows a facile deposition procedure suitable for large‐scale solar receivers. The drone‐deposited coating inhibits cation diffusion and maintains a stable solar absorptance of 97.39±0.20%$97.39\pm 0.20\%$ even after long‐term (3000 h) high‐temperature (800∘C$800 \,^{\circ }\mathrm{C}$) aging. The scalability of developed coating represents a substantial advancement in the implementation of light‐trapping enhancement and maintenance approaches across a wide range of CST applications. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) combine contact electrification and electrostatic induction effects to convert waste mechanical energy into electrical energy. As conventional devices contribute to electronic waste, TENGs based on ecofriendly and biocompatible materials have been developed for various energy applications. Owing to the abundance, accessibility, low cost, and biodegradability of biowaste (BW), recycling these materials has gained considerable attention as a green approach for fabricating TENGs. This review provides a detailed overview of BW materials, processing techniques for BW‐based TENGs (BW‐TENGs), and potential applications of BW‐TENGs in emerging bioelectronics. In particular, recent progress in material design, fabrication methods, and biomechanical and environmental energy‐harvesting performance is discussed. This review is aimed at promoting the continued development of BW‐TENGs and their adoption for sustainable energy‐harvesting applications in the field of bioelectronics. [ABSTRACT FROM AUTHOR]

Summary Early stress detection of crops requires a thorough understanding of the signals showing the very first symptoms of the alterations in the photosynthetic light reactions. Detection of the activation of the regulated heat dissipation mechanism is crucial to complement passively induced fluorescence to resolve ambuiguities in energy partitioning. Using leaf spectroscopy, we evaluated the capability of pigment spectral unmixing to calculate the fluorescence quantum efficiency (FQE) and simultaneously retrieve fast absorption changes in a drought and nitrogen deficiency experiment with tomato. In addition, active fluorescence measurements and pigment analyses of xanthophylls, carotenes and chlorophylls were conducted. We observed notable responses in noninvasive proximal sensing‐retrieved FQE values under stress, but as expected, these alone were not enough to identify the constraints in photosynthetic efficiency. Reflectance‐based detection of the 535‐nm peak absorption change was able to complement FQE and indicate the activation of regulated heat dissipation for both stress treatments under growing light conditions. However, further complexity in the light harvesting energy regulation needs to be accounted for when considering additional light stress. Our results underscore the potential of complementary in vivo quantitative spectroscopy‐based products in the early and nondestructive stress diagnosis of plants, marking the path for further applications. [ABSTRACT FROM AUTHOR]

The concept of multisource energy harvesting has attracted attention in order to harvest multiple types of energy in a single material. In this work, Pb‐free (Ba,Ca)(Zr,Ti)O3 (BCZT) ceramics were used to investigate a combination of piezoelectric and pyroelectric energy harvesting behavior. The temperature dependence of the permittivity and the pyroelectric coefficient was measured, and the pyroelectric properties of BCZT were expected to improve near its orthorhombic–tetragonal phase transition temperature TO–T (∼40°C). The output voltage and current were measured using a BCZT plate, where the BCZT was oscillated under a temperature gradient to apply mechanical stress and temperature fluctuation simultaneously. The measured output voltage from the combined piezo‐ and pyroelectric contributions at a frequency of 2 Hz and with a load resistance of 10 MΩ was 1.4 times higher than the sole piezoelectric output voltage. The resulting combined output voltage was confirmed by finite element simulation. [ABSTRACT FROM AUTHOR]

This study examines a cooperative non-orthogonal multiple access (NOMA) network utilizing an energy-constrained unmanned aerial vehicle (UAV) relay (UAVR) to expand coverage and improve network throughput. In order to provide energy to the UAVR, we consider the hybrid simultaneous wireless information and power transmission (SWIPT) method, which allows the UAVR to harvest energy from the source (i.e., sink node) signal. Herein, a hybrid time switching (TS)-based and power splitting (PS)-based relaying scheme is applied to improve the UAVR's energy harvesting (EH) efficiency and the system performance. Given this context, we derive the closed-form expression of the outage probability (OP) for the sensors to evaluate the network performance. Based on the achieved analytical results, we apply the bat algorithm optimization (BAO) method to determine the optimal working point (as a fraction of received power and power allocation coefficients, and the 3-D positions of the UAVR) for the system such that the OP is minimized. The numerical analysis indicates that BAO is effective in both exploring and exploiting solutions, making it a suitable choice for similar non-convex optimization problems in continuous search spaces for cooperative NOMA IoT networks. [ABSTRACT FROM AUTHOR]

Devices that are employed in applications related to the Internet of Things (IoT) are constrained by limited energy resources. Consequently, ensuring a continuous supply of energy while also maintaining uninterrupted connectivity within IoT units (IoTUs) is of great importance. In this particular context, we present a scheme that facilitates both, the transfer of wireless power and the transmission of information for IoTUs along with the capability of harvesting solar energy. This scheme is further supported by the utilization of unmanned aerial vehicles (UAV) and the deployment of reconfigurable intelligent surfaces (RIS) for communication purposes. To be more precise, initially, IoTUs obtain energy from the UAV through the process of wireless power transmission (WPT). Subsequently, in the second stage, the UAV retrieves data from the IoTUs using transmitting information. In order to simplify the complexity of the communication issue, we assume that a solar-powered UAV remains stationary at a predetermined altitude. Our objective is to maximize the energy efficiency (EE) of the entire network by coordinating the scheduling of IoTU energy harvesting (EH) and UAV trajectory optimization. We suggest a multi-agent federated reinforcement learning (MFRL) algorithm that maximizes EE through parameter optimization in order to achieve this goal. By utilizing the collective experiences of several agents and reducing energy usage, this algorithm also improves the overall performance of the system. The proposed technique achieves 96.3% and 97.5% accuracy in communication rounds and RIS elements, with a 9 − 33 % increase in EE compared to the best-performing benchmark scheme. The suggested approach outperforms the benchmark algorithms in terms of EE, trajectory optimization, and learning accuracy, according to simulation findings. [ABSTRACT FROM AUTHOR]

Numerous efforts have been devoted to harvesting sustainable energy from environment. Among the promising renewable resources, ambient heat exhibits attractive prospects due to its ubiquity and inexhaustibility, and has been converted into electricity through water evaporation-induced hydrovoltaic approaches. However, current hydrovoltaic approaches function only in low-humidity environments and continuously consume water. Herein, we fabricate a hermetic hydrovoltaic cell (HHC) to harvest ambient heat, and have fully addressed the limitations posed by environmental conditions. Meanwhile, for the first time we develop an internal circulation hydrovoltaic mechanism. Taking advantage of the heterogeneous wicking bilayer structure, we verify that inside the hermetic cell, the ambient temperature fluctuation-induced evaporation and further the water circulation can persist, which sustains the hydrovoltaic effect to convert ambient heat into electricity. More importantly, the hermetic design enables the cell to work continuously and reliably for 160 h with negligible water consumption, unaffected by external influences such as wind and light, making it an excellent candidate for extreme situations such as water-scarce deserts, highly humid tropical rain forests, rainy days, and dark underground engineering. These findings provide an easily accessible and widely applicable route for stably harnessing renewable energy, and more notably, offer a novel paradigm toward leveraging low-grade ambient heat energy via circulation design. In this work, authors developed a hermetic hydrovoltaic cell that generates electricity from ambient heat without consuming water. The device operates continuously for 160 h, unaffected by external conditions like wind and light, making it potentially suitable for various challenging environments. [ABSTRACT FROM AUTHOR]

Thermoelectric generators held great promise through energy harvesting from waste heat. Their practical application, however, is greatly constrained by poor raw material utilization and tedious processing in fabricating desired shapes. Herein, a state‐of‐the‐art process is reported for 3D printing the half‐Heusler (Nb0.88Hf0.12FeSb) thermoelectric material using laser powder bed fusion (LPBF). The multi‐dimensional intra‐ and inter‐granular defects created by this process greatly suppress thermal conductivity by providing numerous phonon scattering centers. The resulting LPBF‐fabricated half‐Heusler exhibits a high figure of merit ≈1.2 at 923 K and a single‐leg maximum efficiency of ≈3.3% at a temperature difference (ΔT) of 371 K. Hafnium oxide nanoparticles generated during LPBF effectively prevent crack propagation, ensuring competent mechanical performance and reliable thermoelectric output. The findings highlight the significant potential of LPBF in driving the next industrial revolution of highly efficient and customizable thermoelectric materials. [ABSTRACT FROM AUTHOR]

In the past decade, organic mixed ion-electron conductors have been successfully adopted in innovative bioelectronic, neuromorphic, and electro-optical technologies, as well as in multiple energy harvesting and printed electronics applications. However, despite the intense research efforts devoted to these materials, organic mixed conductors have not yet found application in electronic/photonic devices operating in key regions of the electromagnetic spectrum, such as the microwave (>5 GHz) and terahertz (0.1-10 THz) ranges. A possible reason for this technological gap is the widespread notion that organic electronic materials are unsuitable for high-frequency applications. In this work, we demonstrate for the first time the utility of high-performance polymer mixed conductors as electro-active tuning layers in reconfigurable terahertz metasurfaces, achieving modulation performances comparable with state-of-the-art inorganic and 2D semiconductors. Through time-domain terahertz spectroscopy, we show that the large conductivity modulations of these polymers, until now probed only at very low frequencies, are effectively preserved in the terahertz range, leading to optimal metadevice reconfigurability. Finally, we leverage the unique processability of organic materials to develop fully direct-written electrically tuneable metasurfaces onto both rigid and flexible substrates, opening new opportunities for the mass-scale realization of flexible and light-weight terahertz optics with unique mechanical characteristics and environmental footprint. Organic mixed ion-electron conductors are emerging as promising platforms for innovative bioelectronic, neuromorphic, and electro-optical technologies. In this work, authors explore the potential of this class of electronic materials in THz technologies by developing reconfigurable metasurfaces via direct-writing methods. [ABSTRACT FROM AUTHOR]

Highlights: The 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. High temperature piezoelectric energy harvester (HT-PEH) is an important solution to replace chemical battery to achieve independent power supply of HT wireless sensors. However, simultaneously excellent performances, including high figure of merit (FOM), insulation resistivity (ρ) and depolarization temperature (Td) are indispensable but hard to achieve in lead-free piezoceramics, especially operating at 250 °C has not been reported before. Herein, well-balanced performances are achieved in BiFeO3–BaTiO3 ceramics via innovative defect engineering with respect to delicate manganese doping. Due to the synergistic effect of enhancing electrostrictive coefficient by polarization configuration optimization, regulating iron ion oxidation state by high valence manganese ion and stabilizing domain orientation by defect dipole, comprehensive excellent electrical performances (Td = 340 °C, ρ250 °C > 107 Ω cm and FOM250 °C = 4905 × 10–15 m2 N−1) are realized at the solid solubility limit of manganese ions. The HT-PEHs assembled using the rationally designed piezoceramic can allow for fast charging of commercial electrolytic capacitor at 250 °C with high energy conversion efficiency (η = 11.43%). These characteristics demonstrate that defect engineering tailored BF-BT can satisfy high-end HT-PEHs requirements, paving a new way in developing self-powered wireless sensors working in HT environments. [ABSTRACT FROM AUTHOR]

A triboelectric nanogenerator (TENG) is an emerging energy harvesting technology that utilizes the combination of triboelectrification and electrostatic induction to collect wasted mechanical energy and convert it into electricity. In this work, an aluminosilicate (AS)-based composite, considered as a potential alternative to cement material, has been developed for the fabrication of TENGs. Herein, the AS material is synthesized through the alkali activation of fly ash using a mixture of sodium hydroxide (NaOH) and sodium silicate (Na 2 SiO 3) solutions as activating agents. The electrical output of AS TENGs can be optimized by tuning the liquid-to-solid powder (L/S) ratio during the fabrication of AS composites. The AS composites fabricated at different L/S ratios exhibit the variations in dielectric properties, surface morphology and microstructure. It is found that a high dielectric constant is not the only requirement for achieving optimal TENG output performance. The contribution of dielectric properties and microstructures of the AS composites on TENG performance is discussed. The AS composite with an optimal L/S ratio of 0.5 results in the highest TENG power output density of 2.78 W/m2. Additionally, the versatility of AS TENG to harvest mechanical energy and its application as a power source for portable electronic device are demonstrated. This research has proposed the promising aspect of AS composites as alternative construction materials capable of harvesting mechanical energy, which is essential for the development of green and sustainable power sources. [ABSTRACT FROM AUTHOR]

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. By functionalizing polystyrene with perovskite FAPbBr2I, both the dielectric constant and dielectric strength are controlled, leading to energy-dense composite films for piezoelectric nanogenerators with normalized current density of 25 µA.cm−2 N−1 [ABSTRACT FROM AUTHOR]

Flexible thermoelectric generators (TEGs) with pn-junction single-walled carbon nanotube (SWCNT) films on a polyimide substrate have attracted considerable attention for energy harvesting. This is because they generate electricity through the photo-thermoelectric effect by self-generated temperature gradient under uniform sunlight irradiation. To increase the performance and durability of the pn-junction TEGs, n-type films need to be improved as a priority. In this study, bismuth telluride (Bi2Te3) nanoplates synthesized by the solvothermal method were added to the n-type SWCNT films, including a cationic surfactant to form the nanocomposite films because Bi2Te3 has high n-type thermoelectric properties and high durability. The performances of the pn-junction TEGs were investigated by varying the heat treatment times. When the artificial sunlight was uniformly irradiated to the pn-junction TEGs, a stable output voltage of 0.47 mV was observed in the TEG with nanocomposite films heat-treated at 1 h. The output voltage decreased with increasing heat treatment time due to the decrease in the p-type region. The output voltage of TEG at 1 h is higher than that of the TEGs without Bi2Te3 nanoplates under the same conditions. Therefore, the addition of Bi2Te3 nanoplates was found to improve the performance of the pn-junction TEGs. These findings may aid in the development of facile and flexible optical devices, including photodetectors and hybrid devices integrating solar cells. [ABSTRACT FROM AUTHOR]

Battery-powered sensor nodes encounter substantial energy constraints, especially in linear wireless sensor network (LWSN) applications like border surveillance and road, bridge, railway, powerline, and pipeline monitoring, where inaccessible locations exacerbate battery replacement challenges. Addressing these issues is crucial for extending a network's lifetime and reducing operational costs. This paper presents a comprehensive analysis of the factors affecting WSN energy consumption at the node and network levels, alongside effective energy management strategies for prolonging the WSN's lifetime. By categorizing existing strategies into node energy reduction, network energy balancing, and energy replenishment, this study assesses their effectiveness when implemented in LWSN applications, providing valuable insights to assist engineers during the design of green and energy-efficient LWSN monitoring systems. [ABSTRACT FROM AUTHOR]

A novel 2.4 GHz high-efficiency rectifier circuit suitable for working under very-low-input electromagnetic (EM) power conditions (−20 to −10 dBm) is proposed for typical indoor power harvesting. The circuit features a SMS7630 Schottky diode in a series with a voltage booster circuit at the front end and a direct-current (DC)-pass filter at the back end. The voltage booster circuit consists of an asymmetric coupled transmission line (CTL) and a high-impedance microstrip line (of 100 Ω instead of 50 Ω) to significantly increase the potential at the diode's input, thereby enabling the diode to operate effectively even in very-low-power environments. The experimental measurements show that the microwave direct-current (MW-DC) conversion efficiency of the rectifier circuit reaches 31.1% at a −20 dBm input power and 62.4% at a −10 dBm input power, representing a 7.4% improvement compared to that of the state of the art. Furthermore, the rectifier circuit successfully shifts the input power level corresponding to the peak rectification efficiency from 0 dBm down to −10 dBm. This design is a promising candidate for powering low-energy wireless sensors in typical indoor environments (e.g., the home or office) with low EM energy density. [ABSTRACT FROM AUTHOR]

The proliferation of smart devices increases the demand for energy-efficient, battery-free technologies essential for sustaining IoT devices in Industry 4.0 and 5G networks, which require zero maintenance and sustainable operation. Integrating radio frequency (RF) energy harvesting with IoT and 5G technologies enables real-time data acquisition, reduces maintenance costs, and enhances productivity, supporting a carbon-free future. This survey reviews the challenges and advancements in RF energy harvesting, focusing on far-field wireless power transfer and powering low-energy devices. It examines miniaturization, circular polarization, fabrication challenges, and efficiency using the metamaterial-inspired antenna, concentrating on improving diode nonlinearity design. This study analyzes key components such as rectifiers, impedance matching networks, and antennas, and evaluates their applications in biomedical and IoT devices. The review concludes with future directions to increase bandwidth, improve power conversion efficiency, and optimize RF energy harvesting system designs. [ABSTRACT FROM AUTHOR]

This paper investigates the synthesis and characterization of eco-friendly piezoelectric composite thin films composed of chitosan and Ln2O3-doped Na0.5Bi0.5TiO3-BaTiO3 (NBT-BT) nanoparticles. The films were fabricated using a solution-casting technique, successfully embedding the particles into the chitosan matrix, which resulted in enhanced piezoelectric properties compared to pure chitosan. Characterization methods, such as photoluminescence spectroscopy and piezo-response force microscopy (PFM) which revealed strong electromechanical responses, with notable improvements in piezoelectric performance due to the inclusion of NBT-BT nanoparticles. X-ray diffraction (XRD) analysis revealed a pure perovskite phase with the space group R3c for NBT-BT and NBT-BT-Ln particles. Scanning electron microscopy (SEM) images showed a non-uniform distribution of NBT-BT particles within the chitosan matrix. The results also suggest that the incorporation of rare earth elements further enhances the electrical and piezoelectric properties of the composites, highlighting their potential in flexible and smart device applications. Overall, these findings underscore the potential of chitosan-based composites in addressing environmental concerns while offering effective solutions for energy harvesting and biomedical applications. [ABSTRACT FROM AUTHOR]

A 3D-printable polymer can provide an effective solution for developing piezoelectric structures. However, their nanocomposite formulation and 3D printing processability must be optimized for fabricating complex geometries with high printability. In the present study, we optimized the 3D-printable piezoelectric composite formulation for developing complex geometries by an additive manufacturing approach. The zinc oxide (ZnO) nanomaterial was synthesized by the hydrothermal method. The ZnO loading in the 3D-printed flexible resin was optimized to exhibit good interfacial adhesion and enable 3D printing. The lattice structure was fabricated to improve the piezoelectric response compared with the solid structure. The lattice structure block printed with 10 wt% ZnO showed a good piezoelectric response, with a linear increase in the generated output voltage for an increase in force. The maximum power density of 0.065 μW/cm2 was obtained under 12 N force at 1 Hz. The fabricated structure generated a peak–peak voltage of ~3 V with a foot heel strike. [ABSTRACT FROM AUTHOR]

The sizing of solar energy power plants is usually made using typical meteorological years, which disregards the inter-annual variability of the solar resource. Nevertheless, such variability is crucial for the bankability of these projects because it impacts on the production goals set at the time of the supply agreement. For that reason, this study aims to fill the gap in the existing literature and analyse the impact that solar resource variability has on solar power plant production as applied to the case of Portugal (southern Europe). To that end, 17 years (2003–2019) of meteorological data from a network of 90 ground stations hosted by the Portuguese Meteorological Service is examined. Annual capacity factor regarding photovoltaic (PV) and concentrating solar power (CSP) plants is computed using the System Advisor Model, used here for solar power performance simulations. In terms of results, while a long-term trend for increase in annual irradiation is found for Global Horizontal Irradiance (GHI) and Direct Normal Irradiance (DNI), 0.4148 and 3.2711 kWh/m2/year, respectively, consistent with a solar brightening period, no corresponding trend is found for PV or CSP production. The latter is attributed to the long-term upward trend of 0.0231 °C/year in annual average ambient temperature, which contributes to PV and CSP efficiency reduction. Spatial analysis of inter-annual relative variability for GHI and DNI shows a reduction in variability from the north to the south of the country, as well as for the respective power plant productions. Particularly, for PV, inter-annual variability ranges between 2.45% and 12.07% in Faro and Santarém, respectively, while higher values are generally found for CSP, 3.71% in Faro and 16.04% in São Pedro de Moel. These results are a contribution to future instalments of PV and CSP systems in southern Portugal, a region with very favourable conditions for solar energy harvesting, due to the combination of high production capacity and low inter-annual variability. [ABSTRACT FROM AUTHOR]

Rising environmental concerns and increasing electricity generation costs have sparked significant interest in waste heat recovery systems, particularly thermoelectric modules. Given the challenge of breakthroughs in thermoelectric materials, improving module structure has become a key strategy for enhancing efficiency. This study examines the commercially available TGM1-127-1.0-0.8 thermoelectric module through comparative simulation of flat plate and annular configurations. By maintaining consistent conditions across designs—including total volume of thermoelectric material, element geometry, heat source contact area, temperature differential, and connecting copper plate volume—we investigated the relationship between thermoelectric element quantity and module performance. Results demonstrate that the number of thermoelectric elements not only determines the open-circuit voltage but also significantly influences output power. Notably, the output power trend remains consistent across temperature differentials, independent of load resistance variations, suggesting a fundamental relationship between element quantity and module efficiency. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) energy has been a preferable choice with the rise in global energy demand, as it is a sustainable, efficient, and cost-effective source of energy. Optimizing the power generation is necessary to fully utilize the PV system. Harvesting more power uses cascading of impedance source converters taking input from low-voltage PV arrays which requires multiple maximum power point tracking (MPPT) controllers. To solve this problem, a three-level inverter topology with a proposed PV arrangement, offering higher voltage boosting and a smaller size with a lower cost suitable for low-voltage panels, is designed in this article. The design criteria for parameters are discussed with the help of the small signal analysis. In this paper, three PV arrays are used to harvest maximum energy, which require only one MPPT controller and employ an extended perturb and observe (P&O) algorithm, being faster, highly efficient, and reducing the computational burden of the controller. Moreover, a three maximum power points tracker algorithm, which perturbs one parameter and observes six variables, is designed for the selected converter topology. Finally, the designed 1.1 kVA grid-connected PV system was simulated in MATLAB (R2023a) which shows that the MPPT algorithm offers better dynamics and is highly efficient with a conversion efficiency of 99.2% during uniform irradiance and 97% efficiency during variable irradiance conditions. [ABSTRACT FROM AUTHOR]

This paper models and analyzes the Complementary Metal Oxide Semiconductor (CMOS) cross-coupled differential-drive (CCDD) rectifier for Ultra-Low-Power ambient radio-frequency energy harvesters (RFEHs) working in the subthreshold region. In this paper, two closed-form equations of CCDD rectifier output voltage and input resistance in the subthreshold region were derived based on BSIM4 models of NMOS and PMOS. The model give insight to specify circuit parameters according to different inputs, transistor sizes, threshold voltages, numbers of stages, load conditions and compensation voltages, which can be used to optimize the rectifier circuit. There is a good agreement between the simulation results and these models, and these models have a maximum deviation of 10% in comparison with the simulation results in the subthreshold region. The measurement results of a single-stage CCDD rectifier reported in a previous paper were adopted to verify the model. The output voltage and input resistance predicted by these models provide excellent consistency with corresponding measurement results. The model can be employed to optimize the CCDD rectifier without expensive calculation in the design stage. [ABSTRACT FROM AUTHOR]

Soil contaminated with petroleum-derived products should be used to cultivate energy crops. One such crop is Zea mays. Therefore, a study was performed to determine the suitability of Zea mays biomass obtained from gasoline-contaminated soil for energy purposes. The analysis included determining the heat of combustion and calorific value of the biomass, as well as the content of nitrogen, carbon, hydrogen, oxygen, sulfur, and ash in the biomass. Additionally, the suitability of vermiculite, dolomite, perlite, and agrobasalt for the phytostabilization of gasoline-contaminated soil was evaluated. It was found that the application of sorbents to gasoline-contaminated soil significantly reduced the severe negative effects of this petroleum product on the growth and development of Zea mays. Gasoline contamination of the soil caused a significant increase in ash, nitrogen, and sulfur, along with a decrease in carbon and oxygen content. However, it had no negative effect on the heat of combustion or calorific value of the biomass, although it did reduce the energy production from Zea mays biomass due to a reduction in yield. An important achievement of the study is the demonstration that all the applied sorbents have a positive effect on soil stabilization, which in turn enhances the amount of Zea mays biomass harvested and the energy produced from it. The best results were observed after the application of agrobasalt, dolomite, and vermiculite on gasoline-contaminated soil. Therefore, these sorbents can be recommended for the phytostabilization of gasoline-contaminated soil intended for the cultivation of energy crops. [ABSTRACT FROM AUTHOR]

This work presents the development of a magnetic levitation system with a ferrite core, designed for electromagnetic energy harvesting from mechanical vibrations. The system consists of a fixed enamel-coated copper coil and five neodymium-iron-boron permanent magnets housed within a PVC spool. To enhance magnetic flux concentration, a manganese-zinc ferrite (Mn-Zn) ring was employed within the spool. Experimental tests were conducted at frequencies up to 20 Hz, demonstrating the device's potential for harvesting energy from small vibrations, such as those generated by human biomechanical movements, achieving operating voltages up to 3 V. Additionally, the architecture is scalable for larger systems and allows for the integration of multiple transducers without magnetic field interference, independent of the frequency or excitation phase of each transducer. [ABSTRACT FROM AUTHOR]

This research work aims to design and prototype a DC-DC converter to step up the low voltage of a small, low-power thermoelectric generator (TEG). The system is based on an inductive boost converter and attains a regulated output voltage of 1.2 V. The design's optimisation was based on simulation and experimental validation and it was implemented with only ten low-cost commercial off-the-shelf (COTS) components. To reduce complexity, the low-side switch MOSFET of the boost converter is directly driven by an LC oscillator, switching at 1.25 MHz. For loads above 20 k Ω , the converter ensures voltages higher than 1.2 V, supplied by the TEG voltage of 0.5 V, while registering identical efficiency values to those of more complex and expensive CMOS-integrated solutions. These designed features suggest applications in remote IoT nodes and portable devices, delivering sufficient power to backup the supply of corresponding sensing and communication low-power circuits, reducing the necessity of battery replacements or increasing their lifetime. [ABSTRACT FROM AUTHOR]

A unique oscillating wind-driven triboelectric nanogenerator (OWTENG) based on the sphere's vortex-induced vibration (VIV) behavior is proposed in this study, which can harvest wind energy across a multitude of horizontal directions. With the Euler-Lagrange method, the coupled governing equations of the OWTENG are established and subsequently validated by experimental tests. The vibrational properties and output performance of the OWTENG for varying wind speeds are analyzed, demonstrating its effectiveness in capturing wind energy across a broad range of wind speeds (from 2.20 m/s to 8.84 m/s), and the OWTENG achieves its peak output power of 106.3 µW at a wind speed of 5.72 m/s. Furthermore, the OWTENG maintains a steady output power across various wind directions within the speed range of 2.20 m/s to 7.63 m/s. Nevertheless, when the wind speed exceeds 7.63 m/s, the vibrational characteristics of the sphere shift based on the wind direction, leading to fluctuations in the OWTENG's output power. This research presents an innovative approach for designing vibrational triboelectric nanogenerators, offering valuable insights into harvesting wind energy from diverse directions and speeds. [ABSTRACT FROM AUTHOR]

This study aims to demonstrate the behaviors of a two degree-of-freedom (DOF) dynamical system consisting of attached mass to a nonlinear damped harmonic spring pendulum with a piezoelectric device. Such a system is influenced by a parametric excitation force on the direction of the spring's elongation and an operating moment at the supported point. A negative-velocity-feedback (NVF) controller is inserted into the main system to reduce the undesired vibrations that affect the system's efficiency, especially at the resonance state. The equations of motion (EOM) are derived by using Lagrangian equations. Through the use of the multiple-scales-strategy (MSS), approximate solutions (AS) are investigated up to the third order. The accuracy of the AS is verified by comparing them to the obtained numerical solutions (NS) through the fourth-order Runge-Kutta Method (RK-4). The study delves into resonance cases and solvability conditions to provide the modulation equations (ME). Graphical representations showing the time histories of the obtained solutions and frequency responses are presented utilizing Wolfram Mathematica 13.2 in addition to MATLAB software. Additionally, discusses the bifurcation diagrams, Poincaré maps, and Lyapunov exponent spectrums to show the various behavior patterns of the system. To convert vibrating motion into electrical power, a piezoelectric sensor is connected to the dynamical model, which is just one of the energy harvesting (EH) technologies with extensive applications in the commercial, industrial, aerospace, automotive, and medical industries. Moreover, the time histories of the obtained solutions with and without control are analyzed graphically. Finally, resonance curves are used to discuss stability analysis and steady-state solutions. [ABSTRACT FROM AUTHOR]

Piezothermoelasticity and wave interaction studies hold immense significance in designing functional devices ranging from transducers to sensors for a variety of purposes like energy harvesting and structural health monitoring. These applications catalyze interest in this article which addresses the problem of reflection of plane wave at the boundary of piezothermoelastic half-space. Through this study, the effect of impedance parameter on amplitude and energy ratios of the reflected waves is studied. Four wave modes are indicated upon reflection and a linear system of equations is formed to obtain a closed-form expression for amplitude and energy ratios. These equations are solved by suitable mathematical tools leading to expression for amplitude ratios as a function of incidence angle. For a suitable piezothermoelastic medium, the ratios are plotted against incidence angle and the findings are compared for two well-known theories of thermoelasticity, namely, Lord–Shulman (LS theory) and Green–Lindsay (GL theory). The analytical outcomes suggest approximate values of impedance and incidence angle for preferred energy division between reflected waves. It is recognized that adding impedance increases the amplitude of the quasi-longitudinal (qP) wave and decreases that of the quasi-transverse wave, making it suitable for devices that require a more robust qP wave signal detection. [ABSTRACT FROM AUTHOR]

Barium titanate doped with calcium and zirconium (BCZT) relaxor ferroelectric ceramics enhance energy storage capabilities due to their excellent ferroelectric and dielectric properties. In this investigation, BCZT particles (Ps) were incorporated into poly (vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) using the solvent casting method to prepare biocompatible composite films with varying BCZT Ps contents. The uniform dispersion and distribution of BCZT Ps throughout the polymer matrix results in robust interfacial interactions, promoting improved nucleation of the β-phase in PVDF-HFP and increased thermal stability with higher BCZT Ps loading. The Young's modulus and tensile strength of the composites experienced respective increases of 78.2 % and 41.8 % with the addition of 20 wt% BCZT Ps. While the dielectric constant was improved from 12 to 31. This research contributes to the development of flexible composite films with different BCZT Ps contents, to promote an innovative and environmentally friendly energy harvesting technology. This innovation captures environmental vibrations and converts them into electrical energy to supply a variety of sensors. [ABSTRACT FROM AUTHOR]

• Energy extraction efficiency exhibits dual-peak shape with varying spring stiffness. • The first peak is heavily influenced by leading-edge vortices for lift generation. • It happens when system's natural frequency approximately matches pitching frequency. • Lamb vector, fluid acceleration, and pressure terms dominate lift generation. • The second peak is mainly caused by trailing-edge vortices for torque variations. Flapping airfoil energy harvesting has emerged as a promising paradigm inspired by birds and marine organisms. In this investigation, a semi-passive flapping airfoil device with a predetermined pitching motion was examined using a transient numerical simulation method employing an overlapping grid technique. The impact of the spring stiffness on the energy harvesting characteristics of the flapping airfoil was analyzed through the implementation of the integral momentum theorem and dynamic mode decomposition. The results demonstrated that the efficiency and power curves of the flapping airfoil exhibited a distinctive bimodal M shape in response to variations of the spring stiffness. The initial peak efficiency point, which corresponded to the system's natural frequency in proximity to the pitching frequency, was found to be heavily influenced by the presence of leading-edge vortexes, thereby influencing lift generation. By utilizing the integral momentum theorem, it was determined that the Lamb vector term, fluid acceleration term, and total pressure term predominantly contributed to the lift generation. The emergence of the second peak efficiency point was primarily linked to torque variations induced by trailing-edge vortexes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two kinds of natural and renewable materials are combined to fabricate novel 2D membranes for osmotic energy conversion. • The heterogeneous membranes help to the balance of the trade-off between ion selectivity and ion flux. • A record power density of ∼16.57 W/m2 is achieved with the synergism of space and surface charge. • The ion transport mechanism is theoretically investigated by numerical simulations based on Poisson and Nernst–Planck models. As promising prospects for renewable power harvesting, two-dimensional (2D) nanochannels for osmotic energy capture in a reverse electrodialysis arrangement have garnered significant attention. However, existing 2D nanochannel membranes have shown limited power generation capabilities due to challenges in balancing ion flux and selectivity. Here, we construct montmorillonite (MMT)/TEMPO-mediated oxidation cellulose nanofibers (TOCNFs) nanocomposite membranes for enhanced ion transmembrane transport. The intercalation of TOCNFs not only enlarges the interlayer distance, but also provides abundant space charge inside the nanochannels. Benefiting from the strong ion selectivity and high ion flux, the composite membrane achieves a remarkable power output of ∼16.57 W/m2 in the gradient of artificial seawater and river water, exceeding that of the state-of-the-art heterogeneous membrane-based osmotic energy conversion systems. Both experimental and theoretical findings confirm that the synergism of space and surface charge plays a crucial role in promoting osmotic energy conversion. This research contributes valuable insights into the optimization of 2D membranes for efficient clean energy harvesting purposes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The catalytic mechanism and material preparation based on the piezoelectric effect. • The application of the piezoelectric effect in wastewater purification is expounded. • The development of the piezoelectric effect-assisted water purification technology. • The challenges and prospects of the piezoelectric effect in wastewater purification. The demands of human life and industrial activities result in a significant influx of toxic contaminants into aquatic ecosystems. In particular, organic pollutants such as antibiotics and dye molecules, bacteria, and heavy metal ions are represented, posing a severe risk to the health and continued existence of living organisms. The method of removing pollutants from water bodies by utilizing the principle of the piezoelectric effect in combination with chemical catalytic processes is superior to other wastewater purification technologies because it can collect water energy, mechanical energy, etc. to achieve cleanliness and high removal efficiency. Herein, we briefly introduced the piezoelectric mechanisms and then reviewed the latest advances in the design and synthesis of piezoelectric materials, followed by a summary of applications based on the principle of piezoelectric effect to degrade pollutants in water for wastewater purification. Moreover, water purification technologies incorporating the piezoelectric effect, including piezoelectric effect-assisted membrane filtration, activation of persulfate, and battery electrocatalysis are elaborated. Finally, future challenges and research directions for the piezoelectric effect are proposed. [ABSTRACT FROM AUTHOR]

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Radio frequency (RF) energy harvesting finds application in wireless sensors, RF codes, smart switches, IoT device applications, etc. Contrary to batteries, RF energy harvesting is open to electromagnetic waves coming from different sources and there is no limitation on the dimension and duration of application. A RF energy harvester captures electromagnetic energy from the source to which it is exposed and convert this energy into usable DC voltage. In this paper we propose the fundamental unit of RF harvester, the microstrip patch antenna. Microstrip patch antenna comes with a host of qualities like small size, low price, simple design, less weight, easy fabrication and many more. The proposed microstrip patch RF energy harvest antenna is developed using FR4 substrate with dielectric constant 4.4 and loss tangent 0.009. The substrate comes in between the ground and copper metal patch. Selected target frequency of operations is 2.4 GHz and 5 GHz, which lie in the Wi-Fi band. A microstrip line of width 1.1 mm for 50Ω impedance load matching is used. The antenna is inset-fed. The design and simulation are carried out using High-Frequency Structure Simulator (HFSS) software and the antenna dimensions are due to standard antenna equations. Simulation results achieved gain of 7 dBi at 2.4 GHz with low return loss (S11 parameter). The return loss stands near – 13 dB. The gain of the RF harvester at 5 GHz frequency operation is obtained to be 6 dBi with a remarkable low return loss of – 28 dB. With the given results and stable omnidirectional radiation pattern, the proposed antenna design is suitable for energy harvesting application for mm wave application viz. Bluetooth, Wi-Fi, and WiMAX applications, as an alternate energy source meeting the global energy requirement due to increase in demand of power [ABSTRACT FROM AUTHOR]