Search

Abstract The effective flow of electrons through bulk electrodes is crucial for achieving high-performance batteries, although the poor conductivity of homocyclic sulfur molecules results in high barriers against the passage of electrons through electrode structures. This phenomenon causes incomplete reactions and the formation of metastable products. To enhance the performance of the electrode, it is important to place substitutable electrification units to accelerate the cleavage of sulfur molecules and increase the selectivity of stable products during charging and discharging. Herein, we develop a single-atom-charging strategy to address the electron transport issues in bulk sulfur electrodes. The establishment of the synergistic interaction between the adsorption model and electronic transfer helps us achieve a high level of selectivity towards the desirable short-chain sodium polysulfides during the practical battery test. These finding indicates that the atomic manganese sites have an enhanced ability to capture and donate electrons. Additionally, the charge transfer process facilitates the rearrangement of sodium ions, thereby accelerating the kinetics of the sodium ions through the electrostatic force. These combined effects improve pathway selectivity and conversion to stable products during the redox process, leading to superior electrochemical performance for room temperature sodium-sulfur batteries.

Potassium metal batteries (PMBs) have become a paramount alternative energy storage technology to lithium-ion batteries, due to their low cost and potential energy density. However, uncontrolled dendrite growth interferes with the stability of the interfacial anode, leading to significant capacity degradation and safety hazards. Herein, a facile reactive prewetting strategy is proposed to discourage dendrite growth by constructing a functional KF/Zn-rich hybrid interface layer on K metal. The KF/Zn@K anode design functions like an interconnected paddy field, stabilizing the anode interface through the preferential redistribution of K+ flux/electrons, continuous transport paths, and enhanced transport dynamics. As anticipated, symmetrical batteries exhibit an extended cycling lifetime of over 2000 ​h, with reduced voltage hysteresis at 0.5 ​mA ​cm−2 and 0.5 mAh cm−2. Furthermore, when the KF/Zn@K anode is applied to full batteries coupled with PTCDA, a boosted reversible capacity of 61.6 mAh g−1 at 5 ​C is present over 3000 cycles. This interfacial control creates rational possibilities for constructing high-efficiency, stable K metal anodes.

The negative thermal expansion (NTE) phenomenon is of great significance in fabricating zero thermal expansion (ZTE) materials to avoid thermal shock during heating and cooling. NTE is observed in limited groups of materials, e.g., metal cyanides, oxometallates, and metal-organic frameworks, but has not been reported in the family of metal hydrides. Herein, a colossal and continuous negative thermal expansion is firstly developed in the low-temperature phases of LT1- and LT2-Mg2NiH4 between 488 K and 733 K from in-situ transmission electron microscope (TEM) video, with the volume contraction reaching 18.7% and 11.3%, respectively. The mechanisms for volume contraction of LT1 and LT2 phases are elucidated from the viewpoints of phase transformation, magnetic transition, and dehydrogenation, which is different from common NTE materials containing flexible polyhedra units in the structure. The linear volume shrinkage of LT2 in the temperature of 488–553 K corresponds to the phase transition of LT2→HT with a thermal expansion coefficient of –799.7 × 10–6 K–1 revealed by in-situ synchrotron powder X-ray diffraction. The sudden volume contraction in LT1 between 488 and 493 K may be caused by the rapid dehydrogenation of LT1 to Mg2Ni. The revealed phenomenon in single composite material with different structures would be significant for preparing zero thermal expansion materials by tuning the fraction of LT1 and LT2 phases.

Abstract While multiple external stimuli (e.g., temperature, light, pressure) have been reported to regulate gas adsorption, limited studies have been conducted on controlling molecular admission in nanopores through the application of electric fields (E-field). Here we show gas adsorption capacity and selectivity in zeolite molecular sieves can be regulated by an external E-field. Through E-field pre-activation during degassing, several zeolites exhibited enhanced CO2 adsorption and decreased CH4 and N2 adsorptions, improving the CO2/CH4 and CO2/N2 separation selectivity by at least 25%. The enhanced separation performance of the zeolites pre-activated by E-field was maintained in multiple adsorption/desorption cycles. Powder X-ray diffraction analysis and ab initio computational studies revealed that the cation relocation and framework expansion induced by the E-field accounted for the changes in gas adsorption capacities. These findings demonstrate a regulation approach to sharpen the molecular sieving capability by E-fields and open new avenues for carbon capture and molecular separations.

Abstract Covalent modification is commonly used to tune the channel size and functionality of 2D membranes. However, common synthesis strategies used to produce such modifications are known to disrupt the structure of the membranes. Herein, we report less intrusive yet equally effective non-covalent modifications on Ti3C2T x MXene membranes by a solvent treatment, where the channels are robustly decorated by protic solvents via hydrogen bond network. The densely functionalized (-O, -F, -OH) Ti3C2T x channel allows multiple hydrogen bond establishment and its sub-1-nm size induces a nanoconfinement effect to greatly strengthen these interactions by maintaining solvent-MXene distance and solvent orientation. In sub-1-nm ion sieving and separation, as-decorated membranes exhibit stable ion rejection, and proton-cation (H+/Mn+) selectivity that is up to 50 times and 30 times, respectively, higher than that of pristine membranes. It demonstrates the feasibility of non-covalent methods as a broad modification alternative for nanochannels integrated in energy-, resource- and environment-related applications.

This study describes the capabilities and limitations of carrying out total scattering experiments on the Powder Diffraction (PD) beamline at the Australian Synchrotron, ANSTO. A maximum instrument momentum transfer of 19 Å−1 can be achieved if the data are collected at 21 keV. The results detail how the pair distribution function (PDF) is affected by Qmax, absorption and counting time duration at the PD beamline, and refined structural parameters exemplify how the PDF is affected by these parameters. There are considerations when performing total scattering experiments at the PD beamline, including (1) samples need to be stable during data collection, (2) highly absorbing samples with a μR > 1 always require dilution and (3) only correlation length differences >0.35 Å may be resolved. A case study comparing the PDF atom–atom correlation lengths with EXAFS-derived radial distances of Ni and Pt nanocrystals is also presented, which shows good agreement between the two techniques. The results here can be used as a guide for researchers considering total scattering experiments at the PD beamline or similarly setup beamlines.

Abstract Catalytic conversion of CO2 into high value‐added chemicals using renewable energy is an attractive strategy for the management of CO2. However, achieving both efficiency and product selectivity remains a great challenge. Herein, a brand‐new family of 1D dual‐channel heterowires, Cu NWs@MOFs are constructed by coating metal–organic frameworks (MOFs) on Cu nanowires (Cu NWs) for electro‐/photocatalytic CO2 reductions, where Cu NWs act as an electron channel to directionally transmit electrons, and the MOF cover acts as a molecule/photon channel to control the products and/or undertake photoelectric conversion. Through changing the type of MOF cover, the 1D heterowire is switched between electrocatalyst and photocatalyst for the reduction of CO2 with excellent selectivity, adjustable products, and the highest stability among the Cu‐based CO2RR catalysts, which leads to heterometallic MOF covered 1D composite, and especially the first 1D/1D‐type Mott–Schottky heterojunction. Considering the diversity of MOF materials, the ultrastable heterowires offer a highly promising and feasible solution for CO2 reduction.

Selective CO2 adsorption for efficient carbon capture from flue gas (CO2/N2 - 15/85, v/v) and biogas (CO2/CH4 - 50/50, v/v) is important for achieving global energy and climate goals but remains a challenge due to the lack of effective adsorbents. To address this issue, we attempted to develop zeolite adsorbents by systematically investigating the effect of different extra-framework metal cations (i.e., Na+, Ca2+, Mn2+, and Ce3+-exchanged in LTA zeolites) on selective CO2 adsorption from CO2/N2 and CO2/CH4. Analyzing the isosteric heat of adsorption results showed that CO2 adsorption at moderate pressure (e.g., 15 and 50 kPa relevant to the compositions of flue gas and biogas, respectively) is governed by the gas-framework interaction. On the other hand, the adsorption of N2 and CH4 was found to be dominated by the gas-cation interaction. Therefore, we concluded that metal cations with a small charge-to-size ratio are beneficial for selective CO2 adsorption from flue gas and biogas because they tend to induce strong CO2-framework interaction (due to the enhanced charge induction to zeolite framework O) and weak N2 or CH4-cation interaction (due to the weakened gas-cation electrostatic interaction). Specifically, LTA zeolites in the form of Na+, with the smallest charge-to-size ratio of cation in this study, exhibit the highest CO2 uptake and separation factor of CO2/N2 and CO2/CH4, as demonstrated by both static single-component adsorption and dynamic binary adsorption results. In addition, the potential of metal cation-exchanged LTA zeolites for VSA and PSA processes was evaluated. Our study provides valuable insights for designing small-pore zeolites as adsorbents for carbon capture.

NO2 as a toxic air pollutant causes serious health problems and contributes to environmental damages, which needs to be abated to a harmless level urgently. However, the abatement of low-concentration NO2 pollution under ambient temperature is challenging due to the ineffectiveness of the state-of-the-art deNOx technologies which are only efficient at elevated temperatures (>300 °C). Adsorption is herein studied as an alternative approach for ambient temperature NO2 removal, using transition metal (i.e., Ag+, Cu2+, Co2+, Ni2+, Zn2+, In3+, and Ce3+) ion-exchanged chabazite (CHA) zeolites with different Si/Al ratios (Si/Al = 2, 6, and 12). NO2 is dominantly physiosorbed on the as-prepared samples, which enables the reversible adsorption in cyclic adsorption process. Ni2+ and Co2+ as active adsorption sites showed elevated affinity to NO2 molecules, which was attributed to the formation of Pi-back bonding via the donation of the electrons in dz2 orbital of the metal ions to Pi × orbitals of NO2 molecule, as evidenced by the changes in the electron occupancies in the orbitals of both transition metal ions and NO2 molecule upon NO2 adsorption (DFT calculation). Co2+ ion-exchanged CHA with Si/Al ratio of 2 (Co2+-2-L) showed an outstanding NO2 capacity of 4.65 mmol/g, with a stable NO2 removal performance verified by the adsorption-desorption cycles. The NO release amount of our adsorbents (

Transition metal dissolution from cathode materials limits the cycle life of Li-ion batteries. Here, the authors report an atomic-thin protecting layer on the surface of a high-voltage cathode material, enabling long-term Li-ion battery cycling.

The reaction between solid Fe and liquid Al occupies the important position due to its wide application in industrial processes. However, it is still unclear now which intermetallic compounds will form and the formation mechanism of Fe–Al intermetallic phases. In present work, the Fe–Al solid-liquid reaction by using iron wire as Fe resource is traced by in-situ synchrotron powder X-ray-diffraction. With Fe4Al13 as the dominant phase, two intermetallic phases named Fe4Al13 and Fe2Al5 are found. This phenomenon is different with the result obtained from the diffusion couple of Fe block and melt Al. Thermodynamic calculation and molecular dynamics simulation are performed to verify the underlying mechanism. Related events such as interfacial diffusion and nucleation driving force are analyzed and discussed.

Incomplete conversion of sodium polysulfides represents a significant issue in room-temperature sodium-sulfur batteries. Here, the authors propose Mo5N6 as an electrocatalyst for efficient Na2S electrodeposition and improved cell cycling performances.

The mechanism for the enhanced piezoelectricity in (K,Na)NbO3 based ceramics has not been fully understood. Here, the authors find that the dopants induced tetragonal phase and the accompanying high-density nanoscale heterostructures are responsible for the high dielectric and piezoelectric properties.

Dross in a Zn-55wt%Al-1.6wt%Si metal coating bath is a mixture of bath metal and the quaternary intermetallic phase τ5c-Al20Fe5Si2(+Zn). Understanding the properties and formation of dross in a hot-dip Al-Zn galvanizing bath at the processing temperature (~600 °C) is critical for improving the production quality of steel sheet coating. However, dross analysis is usually conducted at room temperature with dross samples taken from the hot-dip bath and it is not known how representative these samples are of the phase(s) existing at high temperature. Using in-situ synchrotron X-ray diffraction (XRD), the crystal lattice and the coefficient of thermal expansion (CTE) of the intermetallic phase have been determined in the temperature range of 30 °C to 660 °C. Phase formation and phase stability of the intermetallic phase in the dross powder have been determined, providing fundamental knowledge for optimizing the production and quality of steel sheet coating.

Room temperature rechargeable sodium sulfur batteries are promising for next-generation energy storage systems, but their development is limited by polysulfide dissolution and slow kinetics. Here the authors report a cathode that serves as a multifunctional sulfur host and imparts enhanced performance.

Full utilization of ZSM-5 shape-selectivity is restricted by crystal external surface acid sites and co-existence of two different sized channels. Here, the authors synthesize reverse Al zoned ZSM-5 with sinusoidal channel preferentially opened to its inert external surface to achieve 99.3% p-xylene selectivity.

Here Chou and co-authors demonstrate a NASICON-type low-cost Fe-based cathode material for sodium ion batteries. Na4Fe3(PO4)2(P2O7) allows for long-term cycling and high-power density and is featured by its air stability and all-climate property with 3D diffusion pathways for Na+ ions.

Regulating guest access and release in porous materials remains an important goal. Here, May and colleagues elucidate the mechanism by which guest admission can be temperature-regulated in typical microporous materials, and experimentally exploit this process to achieve appreciable and reversible hydrogen storage.

A flow-through reaction cell has been developed for studying minerals leaching by in-situ time-resolved powder X-ray diffraction, allowing for a better understanding of the leaching mechanisms and kinetics. The cell has the capability of independent control of temperature (up to 95 °C) and flow rate (>0.5 mL min−1) for atmospheric pressure leaching. It was successfully tested at the powder diffraction beamline at the Australian Synchrotron. Galena powder was leached in a citrate solution under flow-through condition at a flow rate of 0.5 mL min−1, while diffraction patterns were collected during the entire leaching process, showing rapid galena dissolution without the formation of secondary mineral phases. The flow-through cell can be used to study leaching processes of other ore minerals.

Solid-state reactions between sodium hydride and sodium hydroxide are unusual among hydride-hydroxide systems since hydrogen can be stored reversibly. In order to understand the relationship between hydrogen uptake/release properties and phase/structure evolution, the dehydrogenation and hydrogenation behavior of the Na-O-H system has been investigated in detail both ex- and in-situ. Simultaneous thermogravimetric-differential thermal analysis coupled to mass spectrometry (TG-DTA-MS) experiments of NaH-NaOH composites reveal two principal features: Firstly, an H2 desorption event occurring between 240 and 380 °C and secondly an additional endothermic process at around 170 °C with no associated weight change. In-situ high-resolution synchrotron powder X-ray diffraction showed that NaOH appears to form a solid solution with NaH yielding a new cubic complex hydride phase below 200 °C. The Na-H-OH phase persists up to the maximum temperature of the in-situ diffraction experiment shortly before dehydrogenation occurs. The present work suggests that not only is the inter-phase synergic interaction of protic hydrogen (in NaOH) and hydridic hydrogen (in NaH) important in the dehydrogenation mechanism, but that also an intra-phase Hδ+… Hδ– interaction may be a crucial step in the desorption process.

High hydrostatic pressure (HHP) has been employed to gelatinize or physically modify starch dispersions. In this study, waxy maize starch, normal maize starch, and two high amylose content starch were processed by a HHP of the order of 600 MPa, at 25°C for 15min. The effect of HHP processing on the crystallization of maize starches with various amylose content during storage at 4°C was investigated. Crystallization kinetics of HHP treated starch gels were investigated using rheology and FTIR. The effect of crystallization on the mechanical properties of starch gel network were evaluated in terms of dynamic complex modulus (G*). The crystallization induced increase of short-range helices structures were investigated using FTIR. The pressure releasing rate does not affect the starch retrogradation behaviour. The rate and extent of retrogradation depends on the amylose content of amylose starch. The least retrogradation was observed in HHP treated waxy maize starch. The rate of retrogradation is higher for HHP treated high amylose maize starch than that of normal maize starch. A linear relationship between the extent of retrogradation (phase distribution) measured by FTIR and G* is proposed.