Hot-pressing enhances mechanical strength of PEO solid polymer electrolyte for all-solid-state sodium metal batteries. - In: Small Methods, ISSN 2366-9608, Bd. 0 (2024), 0, 2301579, S. 1-9
Poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) are widely utilized in all-solid-state sodium metal batteries (ASSSMBs) due to their excellent flexibility and safety. However, poor ionic conductivity and mechanical strength limit its development. In this work, an emerging solvent-free hot-pressing method is used to prepare mechanically robust PEO-based SPE, while sodium superionic conductors Na3Zr2Si2PO12 (NZSP) and NaClO4 are introduced to improve ionic conductivity. The as-prepared electrolyte exhibits a high ionic conductivity of 4.42 × 10−4 S cm−1 and a suitable electrochemical stability window (4.5 V vs Na/Na+). Furthermore, the SPE enables intimate contact with the electrode. The Na||Na3V2(PO4)3C ASSSMB delivers a high-capacity retention of 97.1% after 100 cycles at 0.5 C and 60 ˚C, and exhibits excellent Coulombic efficiency (CE) (close to 100%). The ASSSMB with the 20 µm thick electrolyte also demonstrates excellent cyclic stability. This study provides a promising strategy for designing stable polymer-ceramic composite electrolyte membranes through hot-pressing to realize high-energy-density sodium metal batteries.
https://doi.org/10.1002/smtd.202301579
Upgrading cycling stability and capability of hybrid Na-CO2 batteries via tailoring reaction environment for efficient conversion CO2 to HCOOH. - In: Advanced energy materials, ISSN 1614-6840, Bd. 0 (2024), 0, 2304365, S. 1-12
Rechargeable Na-CO2 batteries are considered to be an effective way to address the energy crisis and greenhouse effect due to their dual functions of CO2 fixation/utilization and energy storage. However, the insolubility and irreversibility of solid discharge products lead to poor discharge capacity and poor cycle performance. Herein, a novel strategy is proposed to enhance the electrochemical performance of hybrid Na-CO2 batteries, using water-in-salt electrolyte (WiSE) to establish an optimal reaction environment, regulate the CO2 reduction pathway, and ultimately convert the discharge product of the battery from Na2CO3 to formic acid (HCOOH). This strategy effectively resolves the issue of poor reversibility, allowing the battery to exhibit excellent cycle performance (over 1200 cycles at 30 ˚C), especially under low-temperature conditions (2534 cycles at −20 ˚C). Furthermore, density functional theory (DFT) calculations and experiments indicate that by adjusting the relative concentration of H/O atoms at the electrolyte/catalyst interface, the CO2 reduction pathway in the battery can be regulated, thus effectively enhancing CO2 capture capability and consequently achieving an ultra-high discharge specific capacity of 148.1 mAh cm−2. This work effectively promotes the practical application of hybrid Na-CO2 batteries and shall provide a guidance for converting CO2 into products with high-value-added chemicals.
https://doi.org/10.1002/aenm.202304365
Recent progress and future prospects of high-entropy materials for battery applications. - In: Journal of semiconductors, ISSN 2058-6140, Bd. 45 (2024), 3, 030202, S. 1-5
https://doi.org/10.1088/1674-4926/45/3/030202
Boosting the energy density of bowl-like MnO2carbon through lithium-intercalation in a high-voltage asymmetric supercapacitor with “water-in-salt” electrolyte. - In: Small, ISSN 1613-6829, Bd. 0 (2024), 0, 2310037, S. 1-11
Highly concentrated “‘water-in-salt”’ (WIS) electrolytes are promising for high-performance energy storage devices due to their wide electrochemical stability window. However, the energy storage mechanism of MnO2 in WIS electrolytes-based supercapacitors remains unclear. Herein, MnO2 nanoflowers are successfully grown on mesoporous bowl-like carbon (MBC) particles to generate MnO2/MBC composites, which not only increase electroactive sites and inhibit the pulverization of MnO2 particles during the fast charging/discharging processes, but also facilitate the electron transfer and ion diffusion within the whole electrode, resulting in significant enhancement of the electrochemical performance. An asymmetric supercapacitor, assembled with MnO2/MBC and activated carbon (AC) and using 21 m LiTFSI solution as the WIS electrolyte, delivers an ultrahigh energy density of 70.2 Wh kg−1 at 700 W kg−1, and still retains 24.8 Wh kg−1 when the power density is increased to 28 kW kg−1. The ex situ XRD, Raman, and XPS measurements reveal that a reversible reaction of MnO2 + xLi+ + xe−↔LixMnO2 takes place during charging and discharging. Therefore, the asymmetric MnO2/MBC//AC supercapacitor with LiTFSI electrolyte is actually a lithium-ion hybrid supercapacitor, which can greatly boost the energy density of the assembled device and expand the voltage window.
https://doi.org/10.1002/smll.202310037
Integration of multi-junction absorbers and catalysts for efficient solar-driven artificial leaf structures : a physical and materials science perspective. - In: Solar RRL, ISSN 2367-198X, Bd. 0 (2024), 0, S. 1-88
Artificial leaves could be the breakthrough technology to overcome the limitations of storage and mobility through the synthesis of chemical fuels from sunlight, which will be an essential component of a sustainable future energy system. However, the realization of efficient solar-driven artificial leaf structures requires integrated specialized materials such as semiconductor absorbers, catalysts, interfacial passivation, and contact layers. To date, no competitive system has emerged due to a lack of scientific understanding, knowledge-based design rules, and scalable engineering strategies. Here, we will discuss competitive artificial leaf devices for water splitting, focusing on multi-absorber structures to achieve solar-to-hydrogen conversion efficiencies exceeding 15%. A key challenge is integrating photovoltaic and electrochemical functionalities in a single device. Additionally, optimal electrocatalysts for intermittent operation at photocurrent densities of 10-20 mA cm^-2 must be immobilized on the absorbers with specifically designed interfacial passivation and contact layers, so-called buried junctions. This minimizes voltage and current losses and prevents corrosive side reactions. Key challenges include understanding elementary steps, identifying suitable materials, and developing synthesis and processing techniques for all integrated components. This is crucial for efficient, robust, and scalable devices. Here, we discuss and report on corresponding research efforts to produce green hydrogen with unassisted solar-driven (photo-)electrochemical devices. This article is protected by copyright. All rights reserved.
https://doi.org/10.1002/solr.202301047
Bipolar membrane Electrolyzer for CO2 electro-reduction to CO in organic electrolyte with NaClO produced as byproduct. - In: Electrochimica acta, ISSN 1873-3859, Bd. 483 (2024), 144056, S. 1-8
A novel electrolyzer has been proposed for CO2 reduction to CO, concurrently generating NaClO as a byproduct at the anode. The cell is divided into two compartments by a bipolar membrane, which plays a pivotal role in the dissociation of H2O into H^+ and OH^−. In the cathode compartment, CO2 is reduced to CO within a neutral organic solution. Simultaneously, in the anode compartment, Cl^− undergoes oxidation to form ClO^− within a basic aqueous solution. The electrolyzer remains stable during 10 h of electrolysis, and the current density reaches 76.35 mA cm^−2 at a potential of -2.4 V (vs SHE), with the Faradaic efficiency of CO formation stable at 93 %. By increasing the product values, CO2 electro-reduction technology can be promoted to industrial applications.
https://doi.org/10.1016/j.electacta.2024.144056
Reverse mapping of coarse grained polyglutamine conformations from PRIME20 sampling. - In: ChemPhysChem, ISSN 1439-7641, (2024), e202300521, S. 1-11
An inverse coarse-graining protocol is presented for generating and validating atomistic structures of large (bio-) molecules from conformations obtained via a coarse-grained sampling method. Specifically, the protocol is implemented and tested based on the (coarse-grained) PRIME20 protein model (P20/SAMC), and the resulting all-atom conformations are simulated using conventional biomolecular force fields. The phase space sampling at the coarse-grained level is performed with a stochastical approximation Monte Carlo approach. The method is applied to a series of polypeptides, specifically dimers of polyglutamine with varying chain length in aqueous solution. The majority (>70 %) of the conformations obtained from the coarse-grained peptide model can successfully be mapped back to atomistic structures that remain conformationally stable during 10 ns of molecular dynamics simulations. This work can be seen as the first step towards the overarching goal of improving our understanding of protein aggregation phenomena through simulation methods.
https://doi.org/10.1002/cphc.202300521
Unraveling electron dynamics in p-type indium phosphide (100): a time-resolved two-photon photoemission study. - In: Journal of the American Chemical Society, ISSN 1520-5126, Bd. 146 (2024), 13, S. 8949-8960
Renewable (“green”) hydrogen production through direct photoelectrochemical (PEC) water splitting is a potential key contributor to the sustainable energy mix of the future. We investigate the potential of indium phosphide (InP) as a reference material among III-V semiconductors for PEC and photovoltaic (PV) applications. The p(2 × 2)/c(4 × 2)-reconstructed phosphorus-terminated p-doped InP(100) (P-rich p-InP) surface is the focus of our investigation. We employ time-resolved two-photon photoemission (tr-2PPE) spectroscopy to study electronic states near the band gap with an emphasis on normally unoccupied conduction band states that are inaccessible through conventional single-photon emission methods. The study shows the complexity of the p-InP electronic band structure and reveals the presence of at least nine distinct states between the valence band edge and vacuum energy, including a valence band state, a surface defect state pinning the Fermi level, six unoccupied surface resonances within the conduction band, as well as a cluster of states about 1.6 eV above the CBM, identified as a bulk-to-surface transition. Furthermore, we determined the decay constants of five of the conduction band states, enabling us to track electron relaxation through the bulk and surface conduction bands. This comprehensive understanding of the electron dynamics in p-InP(100) lays the foundation for further exploration and surface engineering to enhance the properties and applications of p-InP-based III-V-compounds for, e.g., efficient and cost-effective PEC hydrogen production and highly efficient PV cells.
https://doi.org/10.1021/jacs.3c12487
Unique gap-related SERS behaviors of p-aminothiophenol molecules absorbed on TiO2 surface in periodic TiO2/Ni nanopillar arrays. - In: Nanotechnology, ISSN 1361-6528, Bd. 35 (2024), 21, 215501, S. 1-11
We observed a unique interpillar gap-related surface-enhanced Raman scattering (SERS) behavior of p-aminothiophenol (PATP) molecules from periodic TiO2 nanopillar arrays with three gap sizes of 191, 297 and 401 nm, which is completely different from that on Ag and Ni nanopillar arrays. Especially, the gap-size-dependent charge-transfer (CT) resonance enhancement from TiO2/Ni has been indicated through comparisons of variation trend of SERS intensities with inter-pillar gap size between TiO2/Ni and Ag/TiO2/Ni as well as Ni nanoarrays, and been confirmed by spectra of ultraviolet-visible absorption and photoluminescence. Results demonstrate that the CT resonance enhancement is more susceptible to the change of the gap size compared with the surface plasmon resonance (SPR) enhancement in TiO2/Ni nanoarrays. Hence, SPR and CT enhancement showing different variation trend and rate with the gap size that leads to a different relative contribution of CT resonance to the overall SERS enhancement as gap size changes, and consequently results in a unique gap-related SERS behavior for TiO2/Ni nanoarrays. The present study is not only helpful for investigating SERS mechanism for semiconductors but also providing a method to design and optimize periodic metal/semiconductor SERS substrates in a controllable way.
https://doi.org/10.1088/1361-6528/ad2a5a
Effect of partial cation replacement on anode performance of sodium-ion batteries. - In: Batteries, ISSN 2313-0105, Bd. 10 (2024), 2, 44, S. 1-13
Due to their high specific capacity and long cycle life, bimetallic sulfides are the preferred choice of researchers as anodes in sodium-ion batteries (SIBs). However, studies indicate that this class of materials often requires expensive elements such as Co, Sb, Sn, etc., and their performance is insufficient with the use of inexpensive Fe, V alone. Therefore, there is a need to explore the relationship between metal cations and anode performance so that the requirements of cost reduction and performance enhancement can be met simultaneously. In this work, a series of partially replaced sulfides with different cation ratios have been prepared by a hydrothermal method followed by heat treatment. By partially replacing Co in NiCo sulfides, all samples show improved capacity and stability over the original NiCo sulfides. As a result, the metal elements have different oxidation states, which leads to a higher capacity through their synergistic effects on each other. Mn-NiCoS with 10% replacement showed satisfactory capacity (721.09 mAh g^−1 at 300 mA g^−1, 662.58 mAh g^−1 after 20 cycles) and excellent cycle life (85.41% capacity retention after 1000 cycles at 2000 mA g^−1).
https://doi.org/10.3390/batteries10020044