Reversible Cycle Research Articles

Silver nanoparticle functionalized heterojunction NiO/SnO2 nanotubes for comprehensive sensitization of acetone sensor

Acetone detection with a good sensitivity and a low operating temperature is crucial owing to the serious harm that acetone can cause to the environment and humans and its importance as a marker of diabetes in human exhalation. One-dimensional (1D) semiconductor metal oxides with easily accessible active sites are potential candidates for use in gas sensors; however, the facile synthesis of 1D nanotubes (NTs) remains a challenge. Herein, Ag–NiO/SnO2 NTs are synthesized via an electrospinning process, followed by spin-coating permeation and subsequent annealing and chemical reduction; furthermore, the gas-sensing properties of the Ag–NiO/SnO2 NTs are investigated. The Ag–NiO/SnO2 NT-based sensor exhibits a rapid response to acetone (12 s) with excellent sensitivity and selectivity at a low operating temperature (190 °C). The lower acetone detection limit of the Ag–NiO/SnO2 NT-based sensor is 50 ppb. The 1D porous NTs efficiently promote gas diffusion during reversible resistance signal cycling and provide numerous active sites. Furthermore, the conjunction of NiO nanograins with SnO2 nanograins forms a heterogeneous construction, enhancing the gas sensitivity of the sensing layers. In addition, Ag nanoparticles homogeneously incorporated onto the surface of the 1D NTs enhance substantially the acetone detection capability based on noble-metal sensitization.

Harnessing eco-friendly additives to manipulate zinc-ion solvation structures towards stable zinc metal batteries

Considerable research efforts have been dedicated to investigating the side reactions and the growth of Zn dendritic in aqueous zinc-ion batteries (AZIBs). The incorporation of organic solvents as additives in electrolytes has yielded highly promising results. Nevertheless, their pervasive use has been hindered by concerns regarding their toxicity, flammability, and economic viability. Herein, we propose the utilization of γ-valerolactone (γ-V), a novel eco-friendly solvent, as an alternative for conventional organic additives to improve the performance of Zn anode. Experimental investigations and theoretical analyses have verified that γ-V additives can diminish the Zn2+-desolvation energy and enhance Zn2+ transport kinetics. The adsorbed γ-V molecules modulate the nucleation and diffusion of Zn2+, facilitating Zn growth along the (002) crystal plane, thus inhibiting dendrite formation and side reactions. Consequently, the modified electrolyte with 3% γ-V exhibit highly reversible cycling for 2800 h at 1 mA cm−2 and 1 mA h cm−2 in Zn//Zn symmetric cell. The Zn//KVOH coin cells deliver a capacity retention of 74.7% after 1000 cycles at 5 A g−1. The Zn//KVOH pouch cells maintain a capacity retention of 78.7% over 90 cycles at 3 A g−1. Notably, the γ-V additives also effectively alleviate the self-discharge phenomenon. This work provides valuable insights on the development of aqueous zinc-ion batteries with superior safety through the modulation of electrolytes using eco-friendly additives.

Copper hydride species activated hypophosphite hydrolysis towards litre-level and high-purity hydrogen production

Large-scale generation of high-purity hydrogen (H2) from simple hydrolysis strategy is vital, but the traditional technologies remain problems of economy and efficiency. Herein, a new and low-cost technical route is highlighted to realize the litre-level and efficient production of high-purity H2 from sodium hypophosphite (NaH2PO2) hydrolysis at room temperature. The formation and stabilization of CuH species on the designed Cu–Cu2O/CuH catalyst plays a key role in stimulating a continuous reversible NaH2PO2 hydrolysis cycle for H2. Impressively, this new technology achieves the high generated rate of 3.3 L h−1•cm−2 for H2 in alkaline media, which outperforms the other existing hydrolysis technologies. The proposed catalytic mechanism involves renewable CuH active species catalyzing the spontaneous reaction of NaH2PO2 and H2O to form H2 gas and phosphate. From the view of practical application, the developed coupling catalytic system also operates efficiently in deionized water, seawater and tap water solutions, shows unique interference immunity and high stability of convenient H2 generation.

Evaluation of the high-robustness nuclear power cycle against lunar surface environmental threat

Heat sinks exposed to the lunar surface environment cause fluctuations in the energy cycle due to variations in lunar thermal conditions, leading to non-design operations of the energy system. Such suboptimal operations decrease energy efficiency and shorten the lifespan of system components. This paper introduces an innovative design for a highly robust lunar nuclear power cycle that mitigates environmental threats on the lunar surface. A reverse closed Brayton cycle increases the waste heat discharge temperature. Higher waste heat temperatures allow the heat sink panels to have greater heat radiation per unit area, countering the negative disturbances from lunar environmental changes on the energy system. Under the dual threats of lunar dust toxicity and intense solar radiation, the output reduction of this robust nuclear cycle is only 0.96% that of traditional nuclear power cycles with the same thermoelectric parameters. Moreover, even under severe environmental threats, the power quality of this robust nuclear cycle remains 10.8 times better than that of conventional designs with the same nighttime output design baseline. In conclusion, employing a reverse Brayton cycle to increase waste heat emission temperature effectively enhances the robustness of the nuclear power cycle. This paper proposes a new nuclear thermoelectric system framework to withstand threats from the lunar surface environment.

Titanium hexacyanoferrate/carbon nanotube composites as the cathode material for aqueous sodium/zinc ion batteries

Aqueous zinc ion batteries (AZIBs), featuring its low cost and environmental protection, are regarded as the promising alternative for traditional energy storage devices acting on clean power generation and electrical vehicles. Prussian blue analogues (PBAs) have received a lot of attention for a potential cathode candidate in AZIBs due to its competence in accommodating various ions with good electrochemical stability. However, conventional PBAs have some inherent problems in Zn ions de-intercalation involving of high discharge potential separation, low structural stability, and high raw material cost. Herein, titanium hexacyanoferrate/carbon nanotube composite (TiHCF-CNT) is synthesized and applied to the cathode materials for aqueous sodium/zinc ion batteries at the first time. The resultant material exhibits not only a high capacity for 134.6 mAh g−1 at 0.05 A g−1, but also excellent cycling stability of 93.7 % capacity retention after 300 cycles at 0.3 A g−1. Na+ in the electrolyte can decrease the resistance of electrolyte and co-insert in the material structure with Zn2+, thus elevate the electrochemical performances remarkably. Moreover, the defects in the structure are identified as Ti vacancies, and these defects can be occupied by Zn2+ reversibly at the charging-discharging process, which lead to a high reversible capacity and cycle stability accordingly.

Stable nature of [BH4]− ions in deliquescence thin-film NaBH4 and humidity control of their decomposition toward hydrogen supply and storage application

In this study, we investigated the deliquescence of NaBH4 thin films under atmospheric conditions toward their hydrogen supply application. Upon exposed to air, the film deliquesced along with generating hydrogen due to the decomposition of [BH4]- ions, but the decomposition rate was slow enough for a sizable amount of [BH4]- ions remained stable in the deliquesced film. As a result, a reversible deliquescence-recrystallization cycle in the NaBH4 thin film could be achieved through control of humidity. Molecular dynamics simulations suggested that Na+ and [BH4]- ions tended to neighbor each other with almost the same intra-distance as that in the crystal. A kind of such local ordered structures in deliquesced NaBH4 may prevent an excess hydration and subsequent decomposition of [BH4]- ions and is responsible for the stability of [BH4]- ions, enabling the reversible deliquescence-recrystallization cycle. These combined experimental and theoretical insights offer new perspectives on controlling hydrogen release from borohydrides based on humidity conditions in the thin film form.

A Symmetric Form of the Clausius Statement of the Second Law of Thermodynamics.

Bridgman once reflected on thermodynamics that the laws of thermodynamics were formulated in their present form by the great founders of thermodynamics, Kelvin and Clausius, before all the essential physical facts were in, and there has been no adequate reexamination of the fundamentals since. Thermodynamics still has unknown possibilities waiting to be explored. This paper begins with a brief review of Clausius's work on the second law of thermodynamics and a reassessment of the content of Clausius's statement. The review tells that what Clausius originally referred to as the second law of thermodynamics was, in fact, the theorem of equivalence of transformations (TET) in a reversible cycle. On this basis, a new symmetric form of Clausius's TET is proposed. This theorem says that the two transformations, i.e., the transformation of heat to work and the transformation of work from high pressure to low pressure, should be equivalent in a reversible work-to-heat cycle. New thermodynamic cyclic laws are developed on the basis of the cycle with two work reservoirs (two pressures), which enriches the fundamental of the second law of thermodynamics.

Design and Implementation of Electrochromic Smart Windows with Self-Driven Thermoelectric Power Generation.

Electrochromic smart windows can achieve controllable modulation of color and transmittance under an external electric field with active light and thermal control capabilities, which helps reduce energy consumption caused by building cooling and heating. However, electrochromic smart windows often rely on external power circuits, which greatly affects the independence and portability of smart windows. Based on this, an electrochromic smart window driven by temperature-difference power generation was designed and implemented. This smart window provides automatic and manual control of the reversible cycle of electrochromic glass from light blue to dark blue according to user requirements and changes in the surrounding environment, achieving adaptive adjustment of visual comfort and reducing energy consumption. The infrared radiation rejection (from 780 to 2500 nm) of the electrochromic smart window is as high as 77.3%, and its transmittance (from 380 to 780 nm) fluctuates between 39.2% and 56.4% with changes in working state. Furthermore, the temperature in the indoor simulation device with electrochromic glass as the window was 15 °C lower than that with ordinary glass as the window after heating with a 250 W Philips infrared lamp for ten minutes. After 2000 cycles of testing, the performance of the smart window was basically maintained at its initial values, and it has broad application prospects in buildings, vehicles, and high-speed rail systems.

DREAM On, DREAM Off: A Review of the Estrogen Paradox in Luminal A Breast Cancers.

It is generally assumed that all estrogen-receptor-positive (ER+) breast cancers proliferate in response to estrogen and, therefore, examples of the estrogen-induced regression of ER+ cancers are paradoxical. This review re-examines the estrogen regression paradox for the Luminal A subtype of ER+ breast cancers. The proliferative response to estrogen is shown to depend on the level of ER. Mechanistically, a window of opportunity study of pre-operative estradiol suggested that with higher levels of ER, estradiol could activate the DREAM-MMB (Dimerization partner, Retinoblastoma-like proteins, E2F4, and MuvB-MYB-MuvB) pathway to decrease proliferation. The response of breast epithelium and the incidence of breast cancers during hormonal variations that occur during the menstrual cycle and at the menopausal transition, respectively, suggest that a single hormone, either estrogen, progesterone or androgen, could activate the DREAM pathway, leading to reversible cell cycle arrest. Conversely, the presence of two hormones could switch the DREAM-MMB complex to a pro-proliferative pathway. Using publicly available data, we examine the gene expression changes after aromatase inhibitors and ICI 182,780 to provide support for the hypothesis. This review suggests that it might be possible to integrate all current hormonal therapies for Luminal A tumors within a single theoretical schema.

Intercalation-Induced Localized Conversion Reaction in h-CuSe for Ultrafast-Rechargeable and Long-Cycling Sodium Metal Battery.

Cathode materials of sodium-based batteries with high specific capacity and fast charge-discharge mode, as well as ultralong reversible cycles at wide applied temperatures, are essential for future development of advanced energy storage system. Developing transition metal selenides with intercalation features provides a new strategy for realizing the above cathode materials. Herein, this work reports a storage mechanism of sodium ion in hexagonal CuSe (h-CuSe) based on the density functional theory (DFT) guidance. This work reveals that the two-dimensional ion intercalation triggers localized redox reaction in the h-CuSe bulk phase, termed intercalation-induced localized conversion (ILC) mechanism, to stabilize the sodium storage structure by forming localized Cu7Se4 transition phase and adjusting the near-edge coordination state of the Cu sites to achieve high reversible capacity and ultra-long cycling life, while allowing rapid charge-discharge cycling over a wide temperature range.

Interfacially Ordered NiCoMoS Nanosheets Arrays on Hierarchical Ti3C2Tx MXene for High‐energy‐density Fiber‐Shaped Supercapacitors with Accelerated Pseudocapacitive Kinetics

Balancing electrochemical activity and structural reversibility of fibrous electrodes with accelerated Faradaic charge transfer kinetics and pseudocapacitive storage are highly crucial for fiber‐shaped supercapacitors (FSCs). Herein, we report novel core‐shell hierarchical fibers for high‐performance FSCs, in which the ordered NiCoMoS nanosheets arrays are chemically anchored on Ti3C2Tx fiber. Beneficial from architecting stable polymetallic sulfide arrays and conductive networks, the NiCoMoS‐Ti3C2Tx fiber maintains fast charge transfer, low diffusion and OH‐ adsorption barrier, and stabilized multi‐electronic reaction kinetics of polymetallic sulfide. Consequently, the NiCoMoS‐Ti3C2Tx fiber exhibits a large volumetric capacitance (2472.3 F cm‐3) and reversible cycling performance (20,000 cycles). In addition, the solid‐state symmetric FSCs deliver a high energy density of 50.6 mWh cm‐3 and bending stability, which can significantly power electronic devices and offer sensitive detection for dopamine.

Near-infrared colorimetric fluorescent probe for detecting HSO3− and its practical application

A colorimetric near-infrared fluorescent probe was designed and synthesized in this paper. The probe XCCC was obtained by simple condensation of 6-(diethylamino)-2,3-dihydro-1H-xanthene-4-carbaldehyde and 3-cyanoacetyl indoles. XCCC detects HSO3− through 1, 4-nucleophilic addition reaction, with obvious near-infrared fluorescence quenching (λem = 696 nm), and the solution color changes from pink to pale yellow under natural light to realize naked eye recognition. In addition, XCCC has a super large Stokes shift value (196 nm) by calculation. The sensitivity of XCCC and HSO3− in the concentration range of 0 ∼ 60 μM is excellent, and the LOD value is as low as 11.4 nM. It is very fast for XCCC to detect HSO3− in real time (30 s), and the reversible cycle of HSO3−- H2O2 is realized (5 times). In practical application, XCCC successfully detected HSO3− qualitatively and quantitatively in actual water samples. Furthermore, we made XCCC into fluorescent test strips to qualitatively detect HSO3− in red wine. In particular, XCCC was used to realize exogenous cell imaging of HSO3− with different concentrations and reversible cell imaging of HSO3−-H2O2 in A549 cells. It shows that probe XCCC has a potential application prospect in food samples and life systems.

Levofloxacin removal by 2D-Vermiculite loaded with NiCo2O4 activated peroxymonosulfate: Performance and mechanism

The presence of antibiotics in wastewater threatens the human living environment. Activated peroxymonosulfate (PMS) method is often used for catalytic degradation of antibiotics. However, how to reduce catalyst cost and ensure efficient degradation of antibiotics at the same time is a sticky issue for the activated PMS method. Two-dimensional vermiculite flakes (2D-VMT) is cost-effective and can be used as catalyst carriers for PMS activation. Hence, we exfoliated 2D-VMT from natural vermiculite and prepared NiCo2O4 loaded 2D-VMT (NiCo2O4/2D-VMT) catalyst. Levofloxacin (LVX), as a normal antibiotic, was used to evaluate the catalytic capacity of NiCo2O4/2D-VMT in PMS systems. Also, LVX degradation mechanism through NiCo2O4/2D-VMT activated PMS were explored here. XRD, EDS, TEM, and HRTEM analysis all demonstrated NiCo2O4 nanoparticles were successfully anchored on 2D-VMT. NiCo2O4/2D-VMT had a high specific surface area and abundant active sites. The NiCo2O4/2D-VMT/PMS system, with a 15% mass ratio of NiCo2O4 to 2D-VMT (15%-CN/2D-VMT), achieved LVX removal efficiency of 87% and LVX removal rate of 0.034 min−1. 1O2 and SO4·- were the major ROS for LVX degradation. The reversible redox cycle between Co(III)/Co(II) and Ni(III)/Ni(II) played a crucial role in activating PMS to generate ROS for LVX degradation process. Also, based on intermediates identification by LC-MS, possible degradation pathways of LVX were proposed and their ecotoxicological evolution was assessed by using the ECOSAR software. 15%-CN/2D-VMT may be a worth recommended loaded catalyst for antibiotics removal in environmental remediation, owing to its high reusability and excellent renewability.

A new concept of ternary aqueous electrolytes based on lithium 4,5-dicyanoimidazolate hydrates

A new concept of aqueous electrolytes based on heterocyclic anions (hydrated anionic triplet electrolyte, HATE) has been presented. Structural studies showed that dimeric lithium 4,5-dicyanoimidazolate (LiTDI) dihydrate molecules, in the presence of acetonitrile, form an ionic system preserved in high concentrations and solid states. X-ray diffraction measurements show that electroneutral dihydrate units can coordinate additional lithium cations acting as charge carriers. The crystalline ionic phase was characterized using spectroscopic, thermal, and electrochemical methods and was used to prepare model electrolytes based on LiTDI hydrates. Linear sweep voltammetry and impedance spectroscopy measurements show, in this system, the depletion of water activity, high conductivity, and reversible cycling of full cells comprising examined electrolytes. We will prove that a concentrated triplet solution acts similarly to the anhydrous electrolyte; regardless of the concentration, it reaches high ionic conductivity values (12–16 mS/cm at room temperature) and is electrochemically stable.

Engineering Sb/Zn4(OH)6SO4·5H2O interfacial layer by in situ chemically reacting for stable Zn anode

Rechargeable aqueous zinc ion batteries with abundant resources and high safety have gained extensive attention in energy storage technology. However, the cycle stability is largely limited by notorious Zn dendrite growth and water-induced interfacial side reactions. Here, a uniform and robust protection layer consisting of metal antimony (Sb) nanoparticles and micrometer-size sheets Zn4(OH)6SO4·5H2O (ZHS) is purposely designed to stabilize Zn anode via an in situ chemical reaction strategy. The two-phase protection layers (Sb/ZHS) induce a reinforcement effect on the Zn anode (Zn@Sb/ZHS). Specifically, Sb nanoparticles play the part of nucleation sites to facilitate uniform Zn plating and homogenize the electric field around the Zn surface. ZHS micrometer-size sheets possess sufficient electrolyte wettability, fast ion transfer kinetics, and anti-corrosion, thus guaranteeing uniform ion flux and inhibiting H2O decomposition. As expected, the symmetric Zn@Sb/ZHS//Zn@Sb/ZHS cells achieve a minimal voltage hysteresis and a reversible cycle of over 2000 h at 1 mA cm−2. By pairing with the MnO2 cathode, the full cell exhibits a significantly improved stability (∼94.17 % initial capacity after 1500 cycles). This study provides a new strategy to design artificial protection layers.

Engineering Porous Carbon with Precise Sizes to Promote Surface‐Dominated Storage in Sodium‐Ion Batteries

AbstractAs the sole commercially viable anode material for sodium‐ion batteries, hard carbon currently faces challenges such as slow diffusion kinetics in the low voltage range and low safety due to sodium deposition. In order to deepen the understanding of the pseudocapacitive processes of hard carbon in the high voltage range and enhance sodium storage capacity, this study systematically investigates the electrochemical performance and ion storage of ZIF‐8‐derived porous carbons (ZPCs) of different sizes. We propose a mathematical model based on a spherical particle core‐shell structure, which profoundly reveals the relationship between size and specific surface area, as well as the linear relationship between specific surface area and specific capacity. Moreover, simply by reducing the size of the porous carbon, the specific capacity increased by 86.5 mAh g−1. Dynamic studies reveal that in nano‐porous carbon materials, sodium‐ion storage primarily relies on defect adsorption. Size reduction enhances physical adsorption and surface capacitance response, with ZPC‐80 exhibiting lower resistance and higher diffusion coefficient, indicating that size reduction improves electronic conductivity and charge transfer efficiency, achieving excellent reversible capacity and cycling stability. This work yields a profound insight into the dynamic characteristics of hard carbon anode materials, presenting a new perspective for the design of efficient sodium‐ion batteries.

Facile Galvanic Replacement Construction of Bi@C Nanosheets Array as Binder‐Free Anodes for Superior Sodium‐Ion Batteries

AbstractBismuth (Bi) possesses an ultrahigh theoretical volume capacity (3800 mAh cm−3) and low embedding potential stimulated considerable attention as anodes for sodium‐ion batteries (SIBs). However, its practical application is still hampered by the huge volume variation during the charge/discharge process. To settle this issue, Bi@C nanosheet arrays (Bi@C‐NSA) are fabricated on copper foam via a facile galvanic replacement followed by in situ polymerization of dopamine and an annealing procedure. The carbon‐coated nanosheet array structure not only accommodates the volume expansion during cycling and maintains electrode stability, but also facilitates rapid electron/ion transport. Due to the unique structural design, this Bi@C‐NSA exhibits an impressive capacity of 315.72 mAh g−1 after 1500 cycles under 1 A g−1. Furthermore, a series of in situ/ex situ techniques reveal that this Bi@C‐NSA possesses superior reaction kinetics and undergoes a typical alloying/dealloying storage mechanism. Furthermore, Bi@C‐NSA also achieves commendable reversible capacity and cycling stability in a wide temperature range (0 °C–60 °C). Notably, the assembled Na3V2(PO4)3//Bi@C‐NSA full cell demonstrates a capacity of 325 mAh g−1 after 50 cycles at 0.05 A g−1, which promises for practical applications. This galvanic replacement strategy spearheads a way to prepare nanoarray electrodes and will accelerate the development of sodium‐ion batteries.

Utilizing Reversed Brayton Cycle for Enhanced Cooling Tower Technology

This study demonstrates an enhanced cooling tower technology (ECTT) under which the ambient air is precooled and dehumidified to improve the cooling tower efficiency. The reverse Brayton cycle, comprising a compressor, an air cooler, an expander, and a heat and mass exchanger, is used to precondition the ambient air before entering the cooling tower. A plant-scale thermodynamic model is constructed for ECTT, and the system parameters are optimized through genetic algorithm based on the maximum power gained from the system, including the effects of reducing the makeup water for the cooling tower. Compared to conventional cooling towers, the ECTT achieved sub-wet bulb cooling of water, which is 9.5 °C below the wet bulb temperature of ambient air, reduces steam condensation temperature by 34%, and increases steam turbine power output by 4.3%. It also reduces evaporative losses in the cooling tower and reduces the makeup water by 36%. With cooling tower exhaust recirculated in a closed loop, makeup water requirements are further reduced with additional gains in power output.

Interfacial bonding enhances MXene/Sb2Se3 composites toward cyclic stability and fast aluminum storage

Metal-chalcogenides have been extensively studied as electrode materials for rechargeable ion batteries due to their high theoretical specific capacity and high abundance. Although promising, these materials face challenges related to slow electrochemical kinetics, pronounced structural distortions, and severe shuttle effects. These issues have seriously hindered the practical application of metal-chalcogenides in ion batteries. This work presents a novel approach to form interfacial binding bonds and in situ generation of antimony selenide (Sb2Se3) on MXene by electrostatic adsorption. This innovative strategy enhances the reversible capacity and cycling stability of Sb2Se3 and effectively improves the electrochemical kinetics and shuttle effect. Ex-situ characterization elucidates the distinctive energy storage mechanism of the Ti3C2/Sb2Se3 cathode and the inhibitory effect of MXene on the dissolution of reaction intermediates into the electrolyte. Additionally, the improvement in charge transfer and ion diffusion due to the introduction of MXene was validated through density functional theory calculations. This work offers new insights into enhancing the stability of metal-chalcogenides and understanding the energy storage mechanism of antimony-based selenides in ion batteries.

Fabrication of FeP2/C/CNTs@3D interconnected graphene aerogel composite for lithium-ion battery anodes and the electrochemical performance evaluation using machine learning

Featuring low cost and high theoretical capacity, phosphorus-rich iron diphosphides (FeP2) have emerged as excellent anode candidates for lithium-ion batteries. However, the typical chemical synthses involving high temperatures and toxic gases have restricted the mass production of FeP2. We now report a FeP2/C/CNTs@3D interconnected graphene aerogel composite synthesized by ball milling and low temperature heat treatment. Because of the unique microstructure and synergistic effect between well-dispersed FeP2 particles and graphene aerogel, the as-prepared FeP2/C/CNTs@GA-2.5% displays excellent lithium storage performance in terms of reversible capacity (886 mA h g−1 at 0.1 A g−1), cycling stability (476 mA h g−1 at 2 A g−1 even after 1000 cycles), and rate capability (685 mA h g−1 at 5 A g−1). Machine learning methods (decision tree and random forest algorithms) prove effective in evaluating and predicting electrochemical performance of the electrode materials.