Additional Energy Input Research Articles

A review of heat transfer enhancement techniques in power systems

The optimization of modern power systems demands that they enhance heat transfer. Analysis has demonstrated the passive use of nanofluids and surface roughness to greatly enhance thermal conductivity as well as increase heat transfer rates, but without requiring the input of additional energy. Meanwhile, active methods, from pulsating flows to electromagnetic fields, have been shown to decrease thermal resistance and improve system performance. Further significant improvements in efficiency are achieved when hybrid approaches combine both passive and active strategies that overcome the limitations of each method individually. This review critically analyses these heat transfer enhancement methods on the grounds of their principles, mathematical models, and experimental results. The paper presents a detailed understanding of how these techniques are applied in a variety of domains, including power generation, renewable energy systems, and high-performance electronics, based on the incorporation of evidence from 20 validated sources. These findings present the transformative potential of these advancements to address fundamental challenges including energy efficiency, component miniaturization, and environmental sustainability.

Low Evaporation Enthalpy Ionic Covalent Organic Frameworks for Efficient Atmospheric Water Harvesting at Low Humidity.

Herein, we introduce a series of ionic covalent organic frameworks (iCOFs) with a focus on addressing the challenge of water collection at low relative humidity levels below 25%. These iCOFs are characterized by numerous hydrophilic sites and high water stability, enabling efficient water vapor adsorption even at relatively low humidity levels. Through the use of various hygroscopic salt cations and precise control of ion concentration within the pores, the water state within the iCOFs pores can be effectively managed. Among the iCOFs, TB-COF-Li stands out with an impressive adsorption capacity of 0.24 g g-1 from 0 to 22% RH. Notably, due to its ionic porous structure, TB-COF-Li exhibits a significantly lower enthalpy of evaporation, measured at 967.04 J g-1, compared to bulk water with an enthalpy of 2387.4 J g-1. Moreover, under simulated conditions of 1.5 solar intensity at 60 °C, the majority of the adsorbed water can be rapidly desorbed without the need for additional energy input. This efficient desorption process contributes to a high water collection rate of 0.092 g g-1 h-1 in the final atmospheric water harvesting device. The development of these iCOFs offers a promising and cost-effective solution for obtaining fresh water in arid regions.

Low Evaporation Enthalpy Ionic Covalent Organic Frameworks for Efficient Atmospheric Water Harvesting at Low Humidity

Herein, we introduce a series of ionic covalent organic frameworks (iCOFs) with a focus on addressing the challenge of water collection at low relative humidity levels below 25%. These iCOFs are characterized by numerous hydrophilic sites and high water stability, enabling efficient water vapor adsorption even at relatively low humidity levels. Through the use of various hygroscopic salt cations and precise control of ion concentration within the pores, the water state within the iCOFs pores can be effectively managed. Among the iCOFs, TB‐COF‐Li stands out with an impressive adsorption capacity of 0.24 g g‐1 from 0 to 22% RH. Notably, due to its ionic porous structure, TB‐COF‐Li exhibits a significantly lower enthalpy of evaporation, measured at 967.04 J g‐1, compared to bulk water with an enthalpy of 2387.4 J g‐1. Moreover, under simulated conditions of 1.5 solar intensity at 60 °C, the majority of the adsorbed water can be rapidly desorbed without the need for additional energy input. This efficient desorption process contributes to a high water collection rate of 0.092 g g‐1 h‐1 in the final atmospheric water harvesting device. The development of these iCOFs offers a promising and cost‐effective solution for obtaining fresh water in arid regions.

Assessing the Spurious Impacts of Ice-Constraining Methods on the Climate Response to Sea Ice Loss Using an Idealized Aquaplanet GCM

Abstract Coupled climate model simulations designed to isolate the effects of Arctic sea ice loss often apply artificial heating, either directly to the ice or through modification of the surface albedo, to constrain sea ice in the absence of other forcings. Recent work has shown that this approach may lead to an overestimation of the climate response to sea ice loss. In this study, we assess the spurious impacts of ice-constraining methods on the climate of an idealized aquaplanet general circulation model (GCM) with thermodynamic sea ice. The true effect of sea ice loss in this model is isolated by inducing ice loss through reduction of the freezing point of water, which does not require additional energy input. We compare the results of freezing point modification experiments with experiments where sea ice loss is induced using traditional ice-constraining methods and confirm the result of previous work that traditional methods induce spurious additional warming. Furthermore, additional warming leads to an overestimation of the circulation response to sea ice loss, which involves a weakening of the zonal wind and storm-track activity in midlatitudes. Our results suggest that coupled model simulations with constrained sea ice should be treated with caution, especially in boreal summer, where the true effect of sea ice loss is weakest, but we find the largest spurious response. Given that our results may be sensitive to the simplicity of the model we use, we suggest that devising methods to quantify the spurious effects of ice-constraining methods in more sophisticated models should be an urgent priority for future work. Significance Statement The potential effects of Arctic sea ice loss on midlatitude weather have been investigated using climate models where sea ice loss is artificially induced, without increasing greenhouse gas concentrations. Recently, this approach has been challenged because the artificial heating used to melt sea ice may also have direct effects on climate, which are not caused by sea ice loss. We run simulations with a simplified climate model that allows us to separate the “spurious” direct effects of the artificial heating from the “true” effect of sea ice loss. In our simulations, the responses of temperature and atmospheric circulation are amplified by spurious effects. Consequently, we argue that previous studies using more complex climate models may overestimate the effect of sea ice loss on climate.

Electrocatalytic nitrate reduction using iron single atoms for sustainable ammonium supplies to increase rice yield

Increasing food production and ensuring drinking water safety have always been a focus of attention, especially for people in underdeveloped regions of the world. Traditional excessive fertilizer applications have increased crop yield but also caused groundwater nitrate pollution. Agricultural irrigating water is an important reservoir for nitrogen (N) (e.g., nitrate) accumulation after fertilization. Ammonium (NH4+-N) is a more readily absorbed N form by rice than nitrate (NO3--N). In this study, we proposed a strategy using iron single-atom catalysts (Fe-SAC) to selectively reduce NO3--N to NH4+-N from the real paddy field irrigating water to provide sustainable NH4+-N supplies for rice uptakes, thereby highlighting decreasing N fertilizer applications and mitigating NO3--N pollution. Then, we constructed a solar-energy-driven electrochemical reactor for NO3--N reduction, with the Fe single atom as the core catalyst, and achieved an average NH4+-N selectivity of 80.2 ± 2.6% with no additional energy input. Sustainable NH4+-N supplies resulted in a 30.4 % increase in the 100-grain weight of the cultivated rice and a 50% decrease of fertilizer application than those of the fertilization group in the pot experiment, which were one of the best values ever reported. Furthermore, the 15N isotope tracing results indicated a N use efficiency (NUE) from 15NO3--N of 71.2 ± 3.2%. Sustainable NH4+-N supplies played a key role in promoting rice root development which contributed to the high NUE. Our study shares unique insights in increasing grain yield, reducing fertilizer applications, and preventing nitrate leaching into groundwater.

Zr-MOF/MXene composite for enhanced photothermal catalytic CO2 reduction in atmospheric and industrial flue gas streams

In this study, a novel composite was engineered by integrating Zr-MOF (NH2-UIO-66) with MXene layers through electrostatic self-assembly. Under simulated sunlight and at 80 °C, this composite material achieved nearly complete conversion of low-concentration atmospheric CO2 to CO and CH4 without additional sacrificial agents or alkaline absorption liquids, marking one of the few reports demonstrating near-complete reduction of low-concentration CO2 directly from the air. For high-concentration CO2 in industrial flue gas, the composite utilized residual heat at 80 °C without additional energy input, exhibiting excellent CO2 reduction efficiency with CO and CH4 production rates of 127 μmol·g-1·h-1 and 330 μmol·g-1·h-1, respectively, resulting in a total production rate 4.76 times higher than that in the air. Compared to most reports on thermocatalytic CO2 reduction (>300 °C), this material shows significant advantages below 100 °C. The performance improvement is attributed to the introduction of Zr-MOF, which provides additional active sites and reduces activation energy. Additionally, the localized surface plasmon resonance (LSPR) effect of MXene facilitates the migration of thermal charge carriers to Zr4+ sites within the MOF. Density Functional Theory (DFT) calculations validate these findings. Overall, Zr-MOF/MXene composite holds potential for reducing CO2 in air and industrial settings, advancing energy conversion and environmental management.

Peroxyacetic acid activated sulfite process: Generation of reactive species and degradation of β-lactam antibiotics

Sulfite advanced oxidation process is a new chemical oxidation technology with strong development potential and can effectively produce many reactive species for the degradation of emerging contaminants (ECs). This study used the peracetic acid activated sulfite advanced oxidation process (PAA/S(IV) process) with no additional energy input and no heavy metal used to degrade typical β-lactam antibiotics. 79.68 % of amoxicillin (AMX) was rapidly degraded in the PAA/S(IV) process within 5 min, and the reaction pH of 7.0∼9.0 is the best degradation effect. In the PAA/S(IV) process, SO4•-, •OH and CH3C(O)OO• that degrade AMX can be produced, and the contribution rates to the AMX degradation were 58.80 %, 22.24 %, and 18.96 %, respectively. The presence of HCO3– and HA cleared •OH and SO4•- affected the formation of CH3C(O)OO• and then delayed the AMX degradation, while the effect of Cl- on the AMX degradation was negligible. Under the action of the reactive species, the β-lactam ring is broken, and five degradation paths are proposed.

(Digital Presentation) Reusability of Copper Nanoparticle-Graphene Nanocomposite Catalysts for Hydrogen Generation

The hydrolysis of sodium borohydride (NaBH4) is a well-studied reaction for generating hydrogen gas to be used as a clean fuel source. The white crystalline powder is stable at room temperature and contains 10.8% hydrogen by weight making it a prime candidate for a method of storing hydrogen and a hydrogen feedstock material for hydrogen generation. The hydrolysis reaction of this material occurs readily without additional energy inputs such as temperature, light, electricity, etc. Thus, many studies have explored different catalysts to optimize this hydrolysis reaction with varying levels of success [1-19]. In this study, we explored a novel catalyst comprised of copper nanoparticles supported on a graphene like material support structure to mitigate nanoparticle agglomeration [1]. This material was tested in five consecutive catalytic trials producing 26.7 mL, 21.0 mL, 25.0 mL, 28.8 mL, and 34.0 mL of hydrogen respectively. It appeared that after an initial drop, the catalyst began producing increasing amounts of hydrogen per trial, possibly indicating that the surface of the nanoparticles was becoming more catalytically active with each usage [1]. The ability of this catalyst to be used multiple times without a loss of catalytic performance, and the availability of copper, makes this a very cost-effective method of producing hydrogen gas for a future hydrogen economy. References Quach, Qui, Erik Biehler, and Tarek M. Abdel-Fattah. Journal of Composites Science, 7, 279 (2023).Biehler, Erik, Qui Quach, and Tarek M. Abdel-Fattah Materials 16, 4779 (2023).Quach, Qui, Erik Biehler, and Tarek M. Abdel-Fattah Catalysts 13, 1117 (2023). Biehler, Erik, Qui Quach, and Tarek M. Abdel-Fattah Nanomaterials 13, 1994 (2023). Biehler, Erik, Qui Quach, and Tarek M. Abdel-Fattah Energies 16, 5053 (2023).Biehler, E.; Quach, Q.; Abdel-Fattah, T.M., ECS J. Solid State Sci. Technol. 2023, 12, 081002.Quach, Q.; Biehler, E.; Elzamzami, A.; Huff, C.; Long, J.M.; Abdel-Fattah, T.M. Catalysts. 2021, 11, 118.Huff, C.; Dushatinski, T.; Barzanji, A.; Abdel-Fattah, N.; Barzanji, K.; Abdel-Fattah, T.M. ECS J. Solid State Sci. Technol. 2017, 6, M69.Huff, C.; Long, J.M.; Aboulatta, A.; Heyman, A.; Abdel-Fattah, T.M. ECS J. Solid State Sci. Technol. 2017, 6, 115–118.Huff, C.; Quach, Q.; Long, J.M.; Abdel-Fattah, T.M., ECS J. Solid State Sci. Technol. 2020, 9, 101008.Huff, C.; Long, J.M.; Heyman, A.; Abdel-Fattah, T.M., ACS Appl. Energy Mater. 2018, 1, 4635–4640.Huff, C.; Dushatinski, T.; Abdel-Fattah, T.M.; 2017, 42 (30), 18985-18990.Dushatinski, T., Huff, C.; Abdel-Fattah, T.M. Applied Surface Science 2016, 385, 282-288Huff, C.; Long, J.M.; Abdel-Fattah, T.M. Catalysts 2020, 10, 1014.Huff, C.; Biehler, E.; Quach, Q.; Long, J.M.; Abdel-Fattah, T.M., Colloid Surf. A 2021, 610, 125734.Biehler, E.; Quach, Q.; Abdel-Fattah, T.M. Catalysts 2024, 14, 423.Biehler, E.; Quach, Q.; Abdel-Fattah, T.M., Energies 2024, 17, 3327.Biehler, E.; Quach, Q.; Abdel-Fattah, T.M. J. Compos. Sci. 2024, 8, 270.Abdel-Fattah, T.M.; Biehler, E. Adv. Carbon J. 2024, 1, 1–19.

Encapsulating Ammonia Borane in Cobalt Decorated Kaolinite Monolith Aerogel for Hydrogen Storage and Controllable Release.

Achieving the "on-off" control of hydrogen release remains a huge challenge in efficiently harnessing hydrogen energy on demand. In this work, a controlled hydrogen production strategy is proposed. Hydrogen carrier ammonia borane (AB) and Co catalyst are loaded into kaolinite aerogel (KA) to obtain a composite AB@Co/KA monolith. The results show that Co particles with surface-oxidized species are uniformly decorated on the surface of aerogel, and AB can fill the pores of aerogel to form a composite hydrogen storage material. Hydrogen generation is modulated on AB@Co/KA by tuning the amount of water added, which achieves an "on-off" hydrogen release on demand. The Co-modified KA (Co/KA) can be repackaged multiple times for recycling use after the AB is completely hydrolyzed. This work provides a promising approach for controlling the release of hydrogen neither the input of additional energy nor foreign reagents added to the reaction system.

Ground motion characteristics induced by high-magnitude events with different source mechanisms of longwall mining

Rockbursts have become one of the most serious hazards in underground mines worldwide. While the characteristics of ground motions before rockbursts (or high-magnitude events (HMEs)) have not been studied. In this study, the peak ground velocity (PGV) and cumulative absolute displacement (CAD) before HMEs were examined based on seismic monitoring in a coal mine. It’s found that the source mechanisms vary significantly across different zones of the longwall, attributed to the low correlation between rock fracture types, stress levels, and seismic intensity. This correlation is mainly related to the distribution of primary fractures within the rock mass. The non-overlap of CAD peak with HME and the induction of delayed rockbursts are mainly caused by the unavoidable creep and additional energy input into the coal mass under disturbances before instability. The energy conversion process of the entire system is determined to be controlled by the stiffness ratio between the roof-floor system and the loaded coal, in accordance with the concept of dynamic and static load superposition. A high static load, strong dynamic disturbances, and a low rigidity ratio between surrounding rock and coal are identified as the most hazardous factors.

Ambient-condition acetylene hydrogenation to ethylene over WS2-confined atomic Pd sites

Ambient-condition acetylene hydrogenation to ethylene (AC-AHE) is a promising process for ethylene production with minimal additional energy input, yet remains a great challenge due to the difficulty in the coactivation of acetylene and H2 at room temperature. Herein, we report a highly efficient AC-AHE process over robust sulfur-confined atomic Pd species on tungsten sulfide surface. The catalyst exhibits over 99% acetylene conversion with a high ethylene selectivity of 70% at 25 oC, and a record space-time yield of ethylene of 1123 molC2H4 molPd−1 h−1 under ambient conditions, which is nearly four times that of the typical Pd1Ag3/Al2O3 catalyst, and exhibiting superior stability of over 500 h. We demonstrate that the confinement of Pd-S coordination induces positively-charged atomic Pdδ+, which not only facilitates C2H2 hydrogenation but also promotes C2H4 desorption, thereby enabling a high conversion of C2H2 to C2H4 at room temperature while suppressing over-hydrogenation to C2H6.

Repurposing Quality-Downgraded Fluorinated Carbon Nanotubes as Eco-Additives in Microgel Composites for Sustained Water Release

While significant efforts have been made to recycle metals like lithium or cobalt for sustainable development in the battery industry, the reuse of other high-value materials, such as fluorinated carbon nanotubes (FCNTs), remains underexplored. This study introduces a novel, eco-friendly method to repurpose quality-downgraded FCNTs (QD-FCNTs) as effective nano-additives in polyacrylamide (PAAm) microgel composites for water retention applications. Because QD-FCNTs are rich in surface defects, by employing a mild surface treatment with a low dosage of organic electron donor N,N,N′,N′-tetramethyl-p-phenylenediamine, we enhanced the hydrophilicity of QD-FCNTs without additional energy input or a large quantity of harmful chemicals. This treatment significantly improved the interaction between QD-FCNTs and PAAm microgels, leading to a 55% increase in water retention time compared to the composites made of untreated QD-FCNTs. Our findings present a sustainable approach to extending the lifecycle of FCNTs, contributing to the circular economy and offering practical solutions for potential water management in agriculture and environmental technologies.

Fabrication of novel MoOx / PVA hydrogel nanocomposite for photochromic smart window

Photochromic smart windows allow for simple manufacturing without the need for additional energy input for adaptive control of sunlight, which will have a huge impact on the comfort of daylight and the development of smart windows. Among them, although molybdenum-based materials have advantages such as low cost and stable coloring, the lack of fast transmission switching capability and liquid phase color changing environment limit its implementation in the field of smart windows. Here, we report a low-cost method to fabricate a novel photochromic hydrogel (MoOx/PVA) by combining molybdenum oxide nanosheets (MoOx, 2 ≤ x ≤ 3) with polyvinyl alcohol (PVA) gel. Under ultraviolet light (UV = 360–400 nm) irradiation, the hydrogel achieves rapid color change visible to the naked eye within 10 s, with an exponential decrease in transmittance, reversible switching of transparency between 70 % and 5 %, and retains about 95 % transmittance after 14 cycles. Due to the good biocompatibility of molybdenum oxide, hydrogel can also be used for personal wearable, which can achieve 1.4 °C of cooling when exposed to sunlight for 3 min. Moreover, the photochromic and recovery properties of the large-sized (29.7 cm × 21 cm) MoOx/PVA hydrogel demonstrate its broad prospects for production applications in smart windows. It is believed that this study will open new opportunities for both fabrication and application in photochromic smart windows and intelligent devices.

A nanofluidic chemoelectrical generator with enhanced energy harvesting by ion-electron Coulomb drag

A sufficiently high current output of nano energy harvesting devices is highly desired in practical applications, while still a challenge. Theoretical evidence has demonstrated that Coulomb drag based on the ion-electron coupling interaction, can amplify current in nanofluidic energy generation systems, resulting in enhanced energy harvesting. However, experimental validation of this concept is still lacking. Here we develop a nanofluidic chemoelectrical generator (NCEG) consisting of a carbon nanotube membrane (CNTM) sandwiched between metal electrodes, in which spontaneous redox reactions between the metal and oxygen in electrolyte solution enable the movement of ions within the carbon nanotubes. Through Coulomb drag effect between moving ions in these nanotubes and electrons within the CNTM, an amplificated current of 1.2 mA cm−2 is generated, which is 16 times higher than that collected without a CNTM. Meanwhile, one single NCEG unit can produce a high voltage of ~0.8 V and exhibit a linear scalable performance up to tens of volts. Different from the other Coulomb drag systems that need additional energy input, the NCEG with enhanced energy harvesting realizes the ion-electron coupling by its own redox reactions potential, which provides a possibility to drive multiple electronic devices for practical applications.

Hybrid Nanoparticle-Enhanced Fluid Flow and Heat Transfer Behaviors in a Parabolic Cavity with a Heat Source

AbstractNatural convection of nanofluids holds considerable importance in both scientific research and engineering applications due to their exceptional heat transfer capabilities, which occur spontaneously without the need for additional energy input. In this paper, the natural convection of nanofluid inside a parabolic cavity containing a hot obstacle is studied numerically. The shape of the hot obstacle is selected as either circular or elliptical. Additionally, the effects of the Rayleigh number, nanoparticle volume fraction, and the position of the heat source are investigated. The computational fluid dynamics model was computed using COMSOL Multiphysics. It is observed that the average Nusselt number tends to increase with both the Rayleigh number and the volume fraction of nanoparticles in the fluid. When the heat source moves from the bottom region to the top area, the heat transfer performance of the heat source increases. When Ra ≤ 105, the cases with circular heat sources exhibit better heat transfer performance than those with elliptical heat sources. However, at Ra = 106, the average Nusselt number of the elliptical heat source is higher than that of the circular one.

Color Design for Daytime Radiative Cooling: Fundamentals and Approaches

The escalating global energy crisis and the worsening global warming have intensified the heat threats posed by high temperatures. Traditional cooling methods like air conditioning are not only energy-intensive but also contribute to environmental degradation. In response, there is a pressing demand for novel, eco-friendly cooling technologies, particularly amid the growing global push for carbon neutrality. As a passive cooling method that does not require any extra power input, radiative cooling offers a promising solution, utilizing thermal radiation to cool the Earth by transferring heat directly to outer space. However, current radiative cooling materials generally have a monotonous white appearance due to their high reflectivity to solar radiation, which, considering their prospects for outdoor applications, has prompted the need for color design. Recent advancements have led to the development of colored passive radiative cooling (CPRC) materials, offering passive cooling without additional energy input, colorful aesthetic appearance, and facile preparation methods. In this review, the latest progress in CPRC materials are summarized, covering fundamental principles, various color design solutions, and potential applications. Besides, the coloration strategy including chemical, structural, and luminescent approaches for CPRC are comprehensively analyzed, providing insights into the future development and deployment of CPRC materials for outdoor energy efficient systems and thermal regulation.

Green extraction of pigment from astaxanthin-producing algae using natural deep eutectic solvents

The high-value carotenoid astaxanthin is a powerful antioxidant with various purported health benefits. The alga Haematococcus lacustris (formerly pluvialis) represents the main natural (farmed) source of astaxanthin. Additionally, Chlamydomonas reinhardtii has been engineered to produce ketocarotenoids including canthaxanthin, astaxanthin, and intermediates that accumulate with its native carotenoids and chlorophylls. Carotenoid extraction from biomass conventionally employs organic solvents such as acetone and ethanol. Here, the use of natural deep eutectic solvents (NADES), composed of food-grade components, was explored as green alternative for the extraction of total pigments, including astaxanthin, from engineered C. reinhardtii and wild-type H. lacustris. Hydrophobic menthol-based NADES extracted up to 2.0 mg of astaxanthin g−1 of dry algal biomass from engineered C. reinhardtii and 13.4 mg g−1 of wildtype H. lacustris, respectively, in single two-hour extractions, giving an extraction efficiency of 79 % and 204 % compared to organic-solvents, respectively. The extractions were carried out at room temperature without necessitating additional energy inputs like heating or sonication and without any pretreatments. The food-grade nature of NADES suggests the feasibility of utilizing the extracted materials in supplements and health applications, offering a cost-effective and sustainable means of converting waste biomass into valuable products.

(Invited) A Hybrid Electrochemical and Catalytic Compression System for Direct Generation of High-Pressure Hydrogen at 350 Atmospheric Pressure

Hydrogen is becoming the center piece in the global de-carbonatization efforts in multiple industrial sectors. Gaseous hydrogen at high pressures in gas tanks is the most common approach for H2 storage, transportation and hydrogen refueling for fuel cell vehicles. Gaseous hydrogen at high pressures is also heavily used in the Haber process for ammonia production and hydro-cracking of heavy petroleum. In the long term, low-cost high pressure H2 will also play a critical role in the future long-duration grid storage for deep decarbonization and improved resilience.In this talk, I will share some recent development on a hybrid electrochemical/catalytic approach for direct generation of high-pressure H2 in collaboration with Pacific Northwest National Laboratory (PNNL). The hybrid system oxidizes water to oxygen at the anode, reduces V3+ to V2+ at the cathode, and stores proton in the catholyte during the “electrochemical charging” step. We demonstrated that the charged catholyte is then capable of generating H2 at >350 bar in the subsequent “catalytic discharging” step without any additional energy input. This concept leverages the electrochemical Nernst potential difference between the redox couple (V2+/3+) and the hydrogen evolution reaction and delivers a unique system that is capable of generating H2 at demand and at high pressure without any mechanical or electrochemical compression. We estimate a cost of <$0.19/kg-H2 for compression, representing >80% of the cost reduction compared to the traditional multi-stage compressor approach.

Affecting the Electropolymerization of Aniline with Permanent Magnets

As portable electronics become more ubiquitous, the demand for different electrochemical energy storage (EES) systems grows. Conductive-polymer-based supercapacitors are an emerging type of EES device promising for their rapid charging and discharging, and among these, polyaniline (PANI) is favored for the ability to deposit it electrochemically from aqueous solutions of monomer. Despite this advantage, supercapacitors fabricated with PANI exhibit poor energy density and cyclability compared to other supercapacitors. In this work, it is shown how a permanent magnet can be applied to affect this electropolymerization, increasing the capacitance of the resultant polymer film by over 70% and increasing its cyclability more than ten-fold. The use of a permanent magnet allows enhancement of the process without the use of any chemical additives or additional energy input, such as from heating, excessive overpotentials, or mechanical stirring. The magnet influences the electropolymerization primarily through the magnetohydrodynamic (MHD) effect, but this work shows that the effect of the magnetic field exceeds that of mechanical stirring. Furthermore, evidence is presented that the influence from the magnet goes beyond forced convection from the MHD effect.

Design and experimental study of a stepped magnetorheological damper with power generation

Traditional vehicle suspension magnetorheological dampers have problems with low output damping force and require additional energy input to operate, to improve the performance of the vehicle suspension magnetorheological damper, in this paper, we propose and investigate a stepped magnetorheological damper structure with power generation, and conducts structural design and magnetic circuit analysis. The effects of different currents, damping gaps, coil slot positions, and coil turns on the damping performance of the stepped magnetorheological damper with power generation are numerically studied. The magnetic circuit sensitivity analysis of the power generation structure and the magnetorheological damper structure is also performed. Experiments have verified the effects of different input excitations on damping and energy-feeding performance, and the results of numerical analysis have been verified. The results show that when the excitation coil is wound for 257 turns, the magnetic circuit requirements are met. And the influence of different amplitudes, frequencies, and currents on the output damping force was studied through experiments. The results showed that the damping force would increase with the increase of single parameter values. When the amplitude was 7 mm, the frequency was 1 Hz, and the current was 2 A, the output damping force could reach 4500 N, meeting the requirements for use.