Energy Conversion Performance Research Articles

Polydimethylsiloxane modified with yeast cells for wearable triboelectric nanogenerator with enhanced energy conversion performance

Polydimethylsiloxane modified with yeast cells for wearable triboelectric nanogenerator with enhanced energy conversion performance

Magnetic Material in Triboelectric Nanogenerators: A Review.

Nowadays, magnetic materials are also drawing considerable attention in the development of innovative energy converters such as triboelectric nanogenerators (TENGs), where the introduction of magnetic materials at the triboelectric interface not only significantly enhances the energy harvesting efficiency but also promotes TENG entry into the era of intelligence and multifunction. In this review, we begin from the basic operating principle of TENGs and then summarize the recent progress in applications of magnetic materials in the design of TENG magnetic materials by categorizing them into soft ferrites and amorphous and nanocrystalline alloys. While highlighting key role of magnetic materials in and future opportunities for improving their performance in energy conversion, we also discuss the most promising choices available today and describe emerging approaches to create even better magnetic TENGs and TENG-based sensors as far as intelligence and multifunctionality are concerned. In addition, the paper also discusses the integration of magnetic TENGs as a power source for third-party sensors and briefly explains the self-powered applications in a wide range of related fields. Finally, the paper discusses the challenges and prospects of magnetic TENGs.

Numerical investigation on the hydrodynamic and conversion performance of a dual cylindrical OWC integrated into a caisson-type breakwater

The hydrodynamic performance of an integrated oscillating water column (OWC) combined with a cylindrical caisson type breakwater was investigated. A three-dimensional numerical wave tank was established to simulate the overall energy conversion performance and hydrodynamics of the integrated system with the software Star-CCM+. The developed Computational Fluid Dynamics (CFD) model was initially verified with the published physical results and numerical results derived from an analytical solution. The effects of the structural geometry and the pneumatic damping of the PTO system on the wave absorption and power conversion efficiency of the proposed device were investigated using this developed model. Based on this proposed numerical model, the velocity of the air flow, the corresponding air pressure characteristics in the air turbine nozzle and chamber zone were discussed. The results indicate that this proposed half-open land based OWC is adapted to absorb shorter nearshore waves, characterized by dimensionless wave number kd approaching 1.49. Furthermore, a larger opening inlet zone for this proposed OWC would shift the resonant corresponding kd to higher wave frequencies, while lowering the opening inlet could help to increase the power extraction efficiency for long waves. The peak hydrodynamic efficiency is observed at a ratio of OWC inlet width to diameter B/D of 0.97, which is approximately six times larger than that at B/D = 0.5. The inclusion of an impulse turbine yields a more uniform pressure distribution within the central chamber and effectively mitigates wave reflection for smaller incident waves, with maximum efficiency achieved using 37 blades. The property of the efficiency mitigation with insufficient certain intake depth of the wave chamber should be avoided for system design.

Improved thermal properties of phase change composites reinforced by Cu nanoparticles modified anisotropic carbon rolls

The scalability of phase change materials (PCMs) for industrial applications is impeded by issues such as leakage during phase transition, suboptimal thermal conductivity, and insufficient photothermal absorption. This research introduces advanced phase change composites (PCCs) reinforced by Cu nanoparticle-enriched porous carbon rolls. These rolls are derived from cotton cloth sheets and are serviced as a scaffold to embed Cu nanoparticles, substantially enhancing interlayer thermal transport. The PCCs are synthesized through a vacuum impregnation process, utilizing paraffin wax as the PCM, yielding a composite with augmented thermal conductivity and improved structural integrity. This innovation elevates anisotropic thermal conductivity values, achieving axial and radial conductivities of 3.4 W/(m·K) and 2 W/(m·K), respectively. The PCCs exhibit advanced solar-thermal-electric energy conversion performance, positioning them as impactful materials for applications in solar energy collection, thermal energy storage, and thermal management.

Large pyroelectric energy conversion in lead scandium tantalate thin films

Non-linear pyroelectric energy harvesting using ferroelectric thin films exhibits high energy conversion, primarily due to their large breakdown field compared to bulks. Here, we report the pyroelectric energy conversion potential of lead scandium tantalate, Pb(Sc1/2Ta1/2)O3 (PST) thin film fabricated on a c-sapphire substrate using chemical solution deposition. To enable the application of high electric field and to assess the pyroelectric energy conversion performance, interdigitated electrodes were deposited on the PST thin film. A maximum harvested energy density of 9.1 J cm−3 per cycle was deduced from polarization measurements in films undergoing an Olsen cycle between 0 °C and 150 °C when the electric field was varied between 50 and 1500 kV/cm. Furthermore, PST thin films can reach up to 27 % of Carnot efficiency for a temperature interval of 10 K between 30 °C and 40 °C. This study highlights the significance of PST thin films for electro-thermal energy harvesting and promising opportunities for enhancing the conversion efficiency and power density using thin films or thin film multi-layer capacitors in the future for thermal energy harvesting.

Promoting effect and kinetic analysis of Fe-Co bimetallic doping on the LaMnO3 catalytic activity for methane combustion

To enhance the catalyst’s properties, a modified sol–gel method is developed in this study, and a unique perovskite catalyst, LaMnxFeyCo1-x-yO3, is successfully synthesized by doping Fe-Co into the lattice of LaMnO3. The catalytic activity of the synthesized catalysts is initially determined by applying them to methane oxidation. Then, the structural, chemical, and surface properties of these catalysts are systematically evaluated utilizing XRD, BET, O2-TPD, H2-TPR, SEM, and XPS analyses. The modified LaMn0.8Fe0.15Co0.05O3 is shown to exhibit excellent activity (T90 at 486.5 ℃) in methane catalytic combustion, comparable to several standard noble metal materials. Experimental findings indicate that such perovskite structures have a larger specific surface area, an elevated molar ratio of Mn4+, desirable low-temperature reducibility, and excellent oxygen mobility relative to the original LaMnO3. Meanwhile, more efficient electron transfer from Mn4+/Mn3+ redox cycles, as well as the emergence of oxygen defects, significantly contribute to the robust interaction between Fe-Co and LaMnO3. Further reaction kinetic analysis is conducted to determine changes in species components and identify possible catalytic pathways. Notably, Fe-Co co-doping leads to an improvement in the increase of lattice oxygen and CH4 adsorption. In addition, the MVK kinetic mechanism governs methane combustion over LaMn0.8Fe0.15Co0.05O3. This study provides new insights into enhancing energy conversion performance and efficient utilization of ventilation air methane (VAM) through the implementation of highly efficient perovskites.

One-dimensional KNN micro rods doping to facilitate the energy conversion performance of a KNN MRs/P(VDF-TrFE) composite

Piezoelectric self-powered electronic devices can convert ambient mechanical vibrations into electrical energy in an environmentally friendly manner, significantly alleviating the scarcity of non-renewable sources. This work prepares an one-dimensional potassium sodium niobate micro rods (1D KNN MRs) using the molten salt - topological chemical reaction method, showing the significant advantages over 0-dimension (0D) nanoparticles due to its anisotropy. Simultaneously, KNN MRs are introduced into poly (vinylidene fluoride-trifluoroethylene) to form a KNN MRs/P(VDF-TrFE) piezoelectric composite, effectively facilitating the piezoelectric β-phase in P(VDF-TrFE) film, and contributing to a high remnant polarization (Pr ∼12.3 μC/cm2) at 125 MV/m and a high piezoelectric constant (d33 = −28 pC/N). Interestingly, a piezoelectric sensor assembled by KNN MRs/P(VDF-TrFE) composite shows a considerable piezoelectric output of 17.6 V at a scene of 2.5 MPa stress, offering a novel route for designing the optimum ceramic/polymer combinations suitable for mechanical energy conversion and energy harvesting.

Complementary Weaknesses: A Win‐Win Approach for rGO/CdS to Improve the Energy Conversion Performance of Integrated Photorechargeable Li−S Batteries

AbstractIntegrating solar energy into rechargeable battery systems represents a significant advancement towards sustainable energy storage solutions. Herein, we propose a win‐win solution to reduce the shuttle effect of polysulfide and improve the photocorrosion stability of CdS, thereby enhancing the energy conversion efficiency of rGO/CdS‐based photorechargeable integrated lithium‐sulfur batteries (PRLSBs). Experimental results show that CdS can effectively anchor polysulfide under sunlight irradiation for 20 minutes. Under a high current density (1 C), the discharge‐specific capacity of the PRLSBs increased to 971.30 mAh g−1, which is 113.3 % enhancement compared to that of under dark condition (857.49 mAh g−1). Remarkably, without an electrical power supply, the PRLSBs can maintain a 21 hours discharge process following merely 1.5 hours of light irradiation, achieving a breakthrough solar‐to‐electrical energy conversion efficiency of up to 5.04 %. Ex situ X‐ray photoelectron spectroscopy (XPS) and in situ Raman analysis corroborate the effectiveness of this complementary weakness approach in bolstering redox kinetics and curtailing polysulfide dissolution in PRLSBs. This work showcases a feasible strategy to develop PRLSBs with potential dual‐functional metal sulfide photoelectrodes, which will be of great interest in future‐oriented off‐grid photocell systems.

Dynamic Energy Conversion Performance of Wearable Annular Thermoelectric Generators for Harvesting Human Body Heat

Dynamic Energy Conversion Performance of Wearable Annular Thermoelectric Generators for Harvesting Human Body Heat

Exploiting multi-stiffness combination inspired absorbers for simultaneous energy harvesting and vibration mitigation

In scenarios where wide-amplitude shock excitation is encountered, a routine bistable configuration struggles to achieve satisfactory energy transfer, and a sensible combination of multiple nonlinear oscillators with different stiffness mechanisms can be exploited to achieve optimal vibration mitigation performance. In this paper, a nonlinear energy conversion and multi-stiffness combination inspired dynamic vibration absorber (NECMC-DVA) is proposed with a magnetic-spring tunable nonlinear stiffness element as the substructure. Parametric studies are performed for different modes of magnet-spring tunable nonlinear stiffness unit arrays considering transient impulses and harmonic excitation. The NECMC-DVA device, which comprises bistable oscillators, cubic stiffness oscillators, and hybrid stiffness oscillators, is also experimentally demonstrated for its synergistic performance in vibration mitigation and energy harvesting. The performance of the NECMC-DVA is measured under transient impulses and harmonic excitations. It has been found that the NECMC-DVA, which consists of a bistable oscillator, a cubic stiffness oscillator, a hybrid stiffness oscillator, energy-capture elements, and motor sequences, achieves high-efficiency nonlinear energy transfer and significant shock robustness in wide-amplitude impulsive scenarios. The NECMC-DVA with hybrid energy sinks demonstrates more remarkable targeted energy transfer and energy conversion performance than its pure bistable oscillator counterpart. Furthermore, the NECMC-DVA prototype can achieve adaptive vibration control modulation and energy conversion management through motion control boards by monitoring ambient excitation signals. Therefore, the NECMC-DVA enables integrated active and passive mitigation and energy harvesting to simultaneously accommodate multi-source indeterminate vibration and shock environments.

Photoinduced charge generation of nanostructured carbon derived from human hair biowaste for performance enhancement in polyvinylidene fluoride based triboelectric nanogenerator

Carbon nanostructures derived from human hair biowaste are incorporated into polyvinylidene fluoride (PVDF) polymer to enhance the energy conversion performance of a triboelectric nanogenerator (TENG). The PVDF filled with activated carbon nanomaterial from human hair (AC-HH) exhibits improved surface charge density and photoinduced charge generation. These remarkable properties are attributed to the presence of graphene-like nanostructures in AC-HH, contributing to the augmented performance of PVDF@AC-HH TENG. The correlation of surface morphologies, surface charge potential, charge capacitance properties, and TENG electrical output of the PVDF composites at various AC-HH loading is studied and discussed. Applications of the PVDF@AC-HH TENG as a power source for micro/nanoelectronics and a movement sensor for detecting finger gestures are also demonstrated. The photoresponse property of the fabricated TENG is demonstrated and analyzed in-depth. The analysis indicates that the photoinduced charge carriers originate from the conductive reduced graphene oxide (rGO), contributing to the enhanced surface charge density of the PVDF composite film. This research introduces a novel approach to enhancing TENG performance through the utilization of carbon nanostructures derived from human biowaste. The findings of this work are crucial for the development of innovative energy-harvesting technology with multifunctionality, including power generation, motion detection, and photoresponse capabilities.

Multi-interfacial bridging engineering of flexible MXene film for efficient electromagnetic shielding and energy conversion

Accompanied by the progressive development of electronic equipment, excellent electromagnetic interference (EMI) shielding materials display a satisfying prospect in protecting electronic devices against electromagnetic pollution/radiation, while integrating energy conversion. Heretofore, it remains a conundrum to availably construct thin films with multi-interfacial bridging engineering as multifunctional shielding devices. To effectively achieve electromagnetic wave attenuation and integrate energy conversion, a co-mixed vacuum-assisted filtration strategy is designed to synthesize Au@MXene/cellulose nanocrystal/dodecylbenzenesulfonic acid-doped polyaniline (AMCP) films. Profited from the interfacial engineering, the total EMI shielding effectiveness (SE) can be increased by 27 % with the highest value of 67.9 dB. MXene with localized surface plasmon resonance characteristics gives the composite films good energy conversion performance, that is, the composite film can be rapidly heated up to 100 °C under the irradiation of an infrared lamp, and its surface temperature remains stable after continuous irradiation. Additionally, the infrared emissivity is as low as 0.173 within the 8–14 μm, which is necessary to adapt various application scenarios. Therefore, it is reliable that the AMCP films constructed by multicomponent offer a facile strategy for MXene-based EMI shielding devices with integration characteristics.

Prediction of Thermionic Energy Conversion Performance and Parametric Effects Using Genetic Algorithms to Fit Physics-Inspired Model Equations to Prototype Test Data

Abstract Thermionic converters have potential as an energy conversion technology for high-temperature space and terrestrial applications using concentrated solar, nuclear reaction, and combustion processes as the heat source. Recent studies have generated experimental performance data for narrow-gap thermionic energy conversion devices. This investigation explores the use of genetic algorithms to fit existing data with physics-inspired model equations. The resulting model equations can be used for performance prediction for system design optimization or to explore parametric effects on performance. The model equations incorporate Richardson’s law for current density, including both the saturated and Boltzmann regimes, with appropriate relations for power delivered to the external load. The transition regime is characterized using two separate models, each accounting for nonuniformity in emission surfaces and irregularities in the manufacturing process. The trained models enable performance prediction of small-gap thermionic energy conversion devices. In this study, data were fitted for two different prototype designs. The prototype test data and postulated values for the work functions and a transition regime parameter are substituted into physics-inspired model equations, yielding performance models with three adjustable constants. Optimized values of these constants are determined using a genetic algorithm to best fit the experimentally determined performance data for prototype thermionic conversion devices tested in earlier studies. This approach is demonstrated to fit the performance data to within 9%. This methodology also allows the user to back-infer the effective work function values, which were found in this study to be consistent with independent measurement.

Improving wave energy conversion performance of a floating BBDB-OWC system by using dual chambers and a novel enhancement plate

In this study, a novel floating dual-chamber backward bent duct buoy oscillating water column (BBDB-OWC) wave energy converter (WEC) is introduced, featuring a horizontal plate at the bottom of the front chamber to act as an enhancement plate. A three-dimensional computational fluid dynamics (CFD) model is developed and validated by comparing its results with existing experimental measurements. The validated model is employed to investigate the hydrodynamic performance and power generation characteristics of the dual-chamber BBDB-OWC WEC under various conditions, including variations in the length of the horizontal plate (lp/lf) and different regular wave conditions. Key performance metrics, including peak to average ratio of power (PTARP), wave energy capture width ratio (ξtotal), and its wave period respond bandwidth (indicated by Pξtotal > 0.5 and Pξtotal > 0.7), are analyzed and compared with those of a traditional single-chamber BBDB-OWC WEC. The results reveal that, compared to the single-chamber WEC, the dual-chamber WEC with a specific horizontal plate length reduces the average PTARP from 2.88 to a minimum value of 1.82 for lp/lf = 0.5, improves the average ξtotal from 0.55 to a maximum value of 0.64 for lp/lf = 2.5, and increases Pξtotal > 0.5 and Pξtotal > 0.7 from 71 % and 14 % to maximum values of 86 % and 43 % for lp/lf = 2.5, respectively. An explanation for these observations is also provided in the context of structure motion and flow fields.

Electrokinetic energy conversion and desalination of an asymmetric nanopore with applied temperature gradients

The electrokinetic energy conversion (EKEC) and desalination performance of a cation-selective funnel-shaped nanopore are investigated theoretically through a continuum description. The effects of pore geometry, characterized by a symmetric factor between the conical and the cylindrical regions, are considered along with pressure and temperature gradients. A desalination index is proposed to evaluate the performance of desalination, examining the trade-off between the ion rejection rate and the volumetric flow rate. It is found that applying a positive (or negative) ∆T relative to ∆P lowers (or raises) the rejection rate, as influenced by the ion selectivity. In addition, the rejection rate at a positive pressure difference (∆P>0; flow coming from tip to base) is slightly larger than that at ∆P<0 because the former has a stronger inlet electric field. Based on the desalination index, a positive ∆T manifests a better desalination performance than a negative ∆T, in contrast to the EKEC case, which displays better energy efficiency under a negative ∆T than under a positive ∆T. The smaller diffusivity of Na+ compared with K+ makes the power density and efficiency of NaCl better than those of KCl. Meanwhile, the more significant thermal diffusion for NaCl impacts its rejection rate more appreciably.

Solar to thermal energy storage performance of composite phase change material supported by copper foam loaded with graphite and boron nitride

Phase Change Materials (PCM) have emerged as one of the potential candidates for solar Thermal Energy Storage (TES) because of their high energy density, low volume change, and easy availability in varying temperature ranges. However, PCM suffers from a few critical drawbacks such as leakage during phase transformation, low thermal conductivity, and poor photothermal energy conversion performance. In this study, shape-stable composite PCM loaded with varying percentages of Graphite (GR) and Boron Nitride (BN) were prepared. Copper foam of 96 PPI was used as 3-dimensional skeleton support to provide shape stability to the eutectic mixture of Lauric Acid (LA)-Myristic Acid (MA). Shape stable composite PCM CF/LA-MA/GR with 0 %, 5 %, 15 %, 25 %, and 35 % of GR and CF/LA-MA/BN with 0 %, 5 %, 15 %, 25 %, and 35 % of BN were prepared and characterized for thermal, physical, and photothermal energy conversion performance. A maximum loading percentage of 67 % of LA-MA in CF without leakage was obtained. The PCM composites show excellent thermal stability at elevated temperatures and suitable TES parameters for solar thermal storage applications. Among all the prepared samples, CF/LA-MA/GR35% shows a maximum rise of 76.1 % in heating rate and 81.2 % in photothermal energy conversion efficiency in comparison with CF/LA-MA/GR0%. In addition, CF/LA-MA/GR35% shows a maximum of 1.08 W/m-K of thermal conductivity at a melting enthalpy of 95.36 J/g. The shape-stable composite PCM shows a stable physical structure along with good surface morphology.

Complementary Weaknesses: A Win-Win Approach for rGO/CdS to Improve the Energy Conversion Performance of Integrated Photorechargeable Li-S Batteries.

Integrating solar energy into rechargeable battery systems represents a significant advancement towards sustainable energy storage solutions. Herein, we propose a win-win solution to reduce the shuttle effect of polysulfide and improve the photocorrosion stability of CdS, thereby enhancing the energy conversion efficiency of rGO/CdS-based photorechargeable integrated lithium-sulfur batteries (PRLSBs). Experimental results show that CdS can effectively anchor polysulfide under sunlight irradiation for 20 minutes. Under a high current density (1 C), the discharge-specific capacity of the PRLSBs increased to 971.30 mAh g-1, which is 113.3 % enhancement compared to that of under dark condition (857.49 mAh g-1). Remarkably, without an electrical power supply, the PRLSBs can maintain a 21 hours discharge process following merely 1.5 hours of light irradiation, achieving a breakthrough solar-to-electrical energy conversion efficiency of up to 5.04 %. Ex situ X-ray photoelectron spectroscopy (XPS) and in situ Raman analysis corroborate the effectiveness of this complementary weakness approach in bolstering redox kinetics and curtailing polysulfide dissolution in PRLSBs. This work showcases a feasible strategy to develop PRLSBs with potential dual-functional metal sulfide photoelectrodes, which will be of great interest in future-oriented off-grid photocell systems.

Light-responsive and ultrapermeable two-dimensional metal-organic framework membrane for efficient ionic energy harvesting

Nanofluidic membranes offer exceptional promise for osmotic energy conversion, but the challenge of balancing ionic selectivity and permeability persists. Here, we present a bionic nanofluidic system based on two-dimensional (2D) copper tetra-(4-carboxyphenyl) porphyrin framework (Cu-TCPP). The inherent nanoporous structure and horizontal interlayer channels endow the Cu-TCPP membrane with ultrahigh ion permeability and allow for a power density of 16.64 W m−2, surpassing state of-the-art nanochannel membranes. Moreover, leveraging the photo-thermal property of Cu-TCPP, light-controlled ion active transport is realized even under natural sunlight. By combining solar energy with salinity gradient, the driving force for ion transport is reinforced, leading to further improvements in energy conversion performance. Notably, light could even eliminate the need for salinity gradient, achieving a power density of 0.82 W m−2 in a symmetric solution system. Our work introduces a new perspective on developing advanced membranes for solar/ionic energy conversion and extends the concept of salinity energy to a notion of ionic energy.

Oriented Growth of Parallel‐Standing Bimetallic Nanosheet Arrays for Enhanced Charge Transfer

AbstractFabricating highly oriented 2D nanosheet arrays is crucial for boosting their performance in electronics, catalysis, optics, and energy conversion, while it remains a challenge due to the high surface energy often leads to random aggregation or interlaced structure. In this study, it is found that the exposed facet of Fe2O3 can greatly influence the interface growth arrangement of bimetallic hydroxide (NiCo(OH)2) nanosheets. The NiCo(OH)2 nanosheets tend to parallel‐standing on the cubic and spindle Fe2O3 while random‐ and interlaced‐standing on the Fe2O3 hexagonal nanoplates and microspheres. The theoretical simulation further indicates the orientation of deposited hydroxide sheets is decided explicitly by the interfacial lattice match/mismatch. Compared to the common interlaced structure of nanosheets, the parallel‐standing nanosheet arrays reduce grain boundaries and improve the charge transfer efficiency. As a result, the derived NiCoP cages exhibit a promising oxygen evolution reaction performance with an overpotential of 255 mV at 10 mA cm−2, and the maximum current density of 400 mA cm−2 with the overpotential of 319 mV.

Manipulating CNT Films with Atomic Precision for Absorption Effectiveness–Enhanced Electromagnetic Interference Shielding and Adaptive Infrared Camouflage

AbstractPromoting advanced functional films that integrate protective behaviors for synergetic radar, infrared (IR), and visible light is confronted with extreme challenges. The effective integration of shielding capacity and IR camouflage into single‐component carbon films remains an enormous challenge because of limited conductivity and high IR absorption. In this work, carbon nanotube (CNT) films with excellent electromagnetic interference (EMI) shielding, switchable IR camouflage, and energy conversion are obtained via a (FCCVD) method and subsequent defect engineering strategies induced by temperature (Strategy I) and N/S co‐doping (Strategy II). Wherein the effect on the electronic configuration as well as multi‐spectra performance is deeply explored. Ascribing to the synergistic effects of strategies, defective CNT films present superior EMI shielding effectiveness (SE) with a high absorption effectiveness ratio of 86.9%, and a large span of emissivity (0.479), which provides the necessary condition for various application scenarios. Under the applied electric field excitation, the IR radiation of CNT films can adapt to rapidly changing surroundings, such as low‐high/high‐low temperatures. Besides, the desirable energy conversion performance and de‐icing can be achieved. This work supplies a feasible strategy for designing EM absorption, adaptive IR camouflage, and energy conversion to confront multiband surveillance.