Multi‐Responsive COF‐Enhanced Smart ActuatorCheng, Gong; Sui, Chao; Hao, Weizhe; Zang, Zifu; Zhao, Yushun; Zhou, Yichen; Zhao, Chenxi; Wen, Lei; Li, Junjiao; Sang, Yuna; He, Xiaodong; Wang, Chao
doi: 10.1002/adfm.202420729pmid: N/A
Smart composite materials are attracting increasing attention for their novel stimulus‐response characteristics. Among them, Cellulose nanofibers (CNF)‐based smart composites are widely used due to their excellent properties. For enhancing the response rate and stability of CNF‐based smart composite actuator, a novel covalent organic framework (COF) nanoparticle is synthesized via molecular design to enhance CNF‐based multi‐responsive composite materials. COF‐TASA, characterized by a high specific surface area, exhibits the highest photothermal conversion efficiency of 79.9% for COF materials to date. A multi‐stimuli responsive actuator is prepared through the compounding of COF‐TASA, CNF, and polyvinylidene fluoride (PVDF). The smart membrane demonstrates a reversible ability to change shape when exposed to near‐infrared (NIR) light and humidity. This is caused by the asymmetric deformation of the COC and PVDF layers. Finally, the mechanism for the enhancement of the smart response rate of the system by COF‐TASA is successfully elucidated through experiments and molecular dynamics (MD) simulations, indicating that the introduction of COF forms ordered channels in the COC, greatly enhancing the specific surface area and the transport speed of water molecules. This COF‐enhanced smart actuator is anticipated to provide important solutions for smart control, smart detection, and environmental energy collection.
Fabricating Open‐Framework Using Polyoxovanadate Clusters for Efficient Removal of Radioactive Cs+ and Sr2+Cheng, Lin; Li, Si‐Yu; Zhang, Yu‐Jie; Meng, Xin; Wang, Ying; Wang, Shuaihua; Wang, Kai‐Yao
doi: 10.1002/adfm.202424406pmid: N/A
Innovation of 137Cs+ and 90Sr2+ ion exchangers is achieved through heteroatom‐bridged integration of polyoxovanadate clusters, whose soft Lewis basic nature and large size promote the selective capture of cesium/strontium radionuclides. The radiolytically stable Na6P4V10O34·19H2O (VPO‐1) features an interlinkage of {NaV10O26} clusters and phosphorus bridges, forming nanoscale voids with hydration‐lubricated sodium ions. This structure endows VPO‐1 with remarkable exchange kinetics (k2Cs = 3.774 g mg−1 min−1; k2Sr = 1.376 g mg−1 min−1), equilibrium removal (R > 99.3% within 5–10 min), and maximum capacities (qmCs = 300.32 mg g−1; qmSr = 113.00 mg g−1). The exchange mechanism is illuminated through single‐crystal XRD by revealing cluster‐vacancy pathways and ionic‐radius‐dependent adsorption sites. VPO‐1 exhibits stability across pH = 3–12, with exceptional KdCs and KdSr values above 105 mL g−1, and high selectivity for Cs+ and Sr2+ over various competing ions. These properties enable excellent column filtration performance (R = 99%–100%) for mixed Cs+ and Sr2+ during a 3000 mL test. Deep cleaning of these ions is also possible via suction filtration using an ultra‐thin VPO‐1/PTFE membrane, with high exchange activity (R = 98.8%–99.9%) retained after simple regeneration with 2 m NaCl, offering significant potential for nuclear wastewater treatment applications.
Multifunctional Reconfigurable Electromagnetic Metamaterials Based on Compression‐Torsion Coupling Structures for Transmission Modulations and Holographic DisplaysHe, Shuchang; Yao, Xincheng; Tao, Jie; Wang, Kai; Tang, Haishan; Wang, Chengjun; Gao, Fei; Wang, Zuojia; Song, Jizhou
doi: 10.1002/adfm.202421065pmid: N/A
Mechanically controlled reconfigurable electromagnetic metamaterials that can dynamically modulate their electromagnetic properties by simple mechanical compression/stretch hold great potential in wavefront control, tunable filtering, and holographic display. Undesired operating frequency shift and difficult independent controlling of unit cells in existing mechanically controlled reconfigurable metamaterials greatly limit their wide developments. Here, a multifunctional reconfigurable electromagnetic metamaterial based on a compression‐torsion coupling structure with the unit cell featuring a split‐ring resonator, a pair of parallel square frames, and four inclined beams between the frames, is reported. The unit cells can be globally or selectively compressed to induce the uniform or patterned in‐plane rotations of split‐ring resonators, enabling the multifunctionalities of electromagnetic transmission modulation and holographic display, which are not easily accessible by existing mechanically controlled electromagnetic metamaterials based on in‐plane compression and tension schemes. Numerical and experimental studies are carried out to reveal the design and operation of reconfigurable metamaterials enabled by the compression‐torsion coupling structure. Demonstrations of the metamaterials in modulating the transmittance of linearly polarized waves with stable resonant frequencies and multi‐imaged holographic display functions illustrate the versatility and feasibility of compression‐torsion strategy in realizing multifunctional electromagnetic metamaterials.
Premixed Exciplex Co‐Host for Constructing High‐Performance Organic Light‐Emitting DiodesNie, Yufang; Jiang, Chao; Cao, Chi; Liang, Baoyan; Zhuang, Xuming; Bi, Hai; Wang, Yue
doi: 10.1002/adfm.202419495pmid: N/A
Exciplex, characterized by intermolecular charge transfer and thermally activated delayed fluorescence (TADF) properties, plays a significant role in organic light‐emitting diodes (OLEDs), particularly as co‐hosts. The rapid rate of reverse intersystem crossing (RISC) and balanced carrier mobility contribute to improved efficiency and suppressive efficiency roll‐off at high current density. Despite these advantages, the fabrication of devices using two‐component exciplexes is challenging, especially when the emitting layers require the simultaneous evaporation of three or four materials from separate crucibles. To address this issue, a pair of premixed exciplex co‐hosts is developed and utilized as the co‐host for Ir(ppy)3. The consistent performance of continuous parallelly fabricated devices with the same premixed co‐host sample indicates the long‐term stability of the premixed exciplex co‐host and the stable evaporation ratio of the electron donor and electron acceptor molecules. The devices achieve maximum luminance over 250 000 cd m−2, a maximum external quantum efficiency of 21.9%, a regardless efficiency roll‐off of 4.6% at 10 000 cd m−2, along with a prolonged operational LT95(lifetime to 95% of the initial luminance) of 165 h at the current density of 10 mA cm−2. Further enhancement in device performance is observed through co‐doping a multiple resonance TADF (MR‐TADF) material in the emitting layer, underscoring the significant potential for industrial application.
Unlocking the Potential: Na4Fe3(PO4)2(P2O7) Supporting the Innovation of Commercial Sodium‐Ion BatteriesLiu, Cong; Zhang, Zhi; Liao, Huanyi; Jiang, Yumeng; Zheng, Yifan; Li, Zhongxi; Gao, Yihua
doi: 10.1002/adfm.202424759pmid: N/A
Sodium‐ion batteries (SIBs) are highly anticipated as an efficient energy storage solution in addressing contemporary energy challenges. The pursuit of high‐performance cathode materials is critical for the commercialization of SIBs. Among the contenders, Na4Fe3(PO4)2(P2O7) (NFPP) is one of the most promising commercial cathode materials due to its stable structure framework and excellent sodium storage capability. Although the research on NFPP has achieved great progress, especially in the last 10 years, the timely and dedicated summary of the research progress and prospect of this rising star of cathode materials for SIBs has not been reported. This review provides a comprehensive overview of the advancement and prospect of NFPP as commercial cathode material in SIBs. In this review, the crystal structure and sodium storage mechanism of NFPP are examined first. Then, different proposed preparation methods of NFPP have been elaborated in the following section. After that, the optimization strategies are discussed to enhance the sodium storage performance of NFPP cathode material in detail. At last, the gap between current research and the practical application of NFPP is highlighted, and possible future research directions for the commercialization of NFPP cathode material in SIBs are proposed.
Crystalline Hydrogen Enhanced Dual‐Acid Quasi‐Solid‐State Proton BatteryMeng, Fanhao; Dong, Xiaoyu; Wu, Haiyang; Wu, Zhiyuan; Dou, Hui; Zhang, Xiaogang
doi: 10.1002/adfm.202422079pmid: N/A
Proton batteries are considered promising due to their high‐power output, cost‐effectiveness, and safety. However, they also face challenges such as low voltage, limited capacity, and poor cycle stability. To address these challenges, a dual‐acid quasi‐solid‐state electrolyte (SSAE) is developed by combining H2SiO3 with H2SO4. This electrolyte has the decomposition voltage of 2.15 V and ultra‐high conductivity of 95 mS cm⁻¹ (1.5 mS cm⁻¹ at −70 °C). Leveraging this high decomposition voltage, the specific capacity of MoO3 is successfully enhanced to 1.74 times than its original value at a current density of 5 A g−1 by harnessing the hydrogen evolution/oxidation reaction (HER/HOR) of lattice hydrogen (H·ad,s) in MoO3 at low potentials, which is typically regarded as a significant factor to suppress the gas evolution. Notably, the voltage achieved a record‐breaking 1.8 V in the Prussian Blue Analog //MoO3 system at room temperature. The full cell consisting of HVFe‐PBA (pre‐protonated vanadium hexacyanoferrate)//SSAE//MoO3 exhibited outstanding electrochemical performance at both room temperature and low temperatures. As a proof‐of‐concept, a pouch cell is assembled with an energy density of 72.3 Wh kg−1, and even it maintained an energy density of 40.7 Wh kg−1at −60 °C.
Spin Pumping in Magnetostrictive Galfenol Interfaced with TaSahoo, Ajit Kumar; Mukhopadhyay, Suchetana; Baghira, Bikram; Chelvane, Jeyaramane Arout; Mohanty, Jyoti Ranjan; Barman, Anjan
doi: 10.1002/adfm.202424006pmid: N/A
In view of their advantages for memory and storage applications, the quest to find suitable magnetic thin film heterostructures that can exhibit strong spin pumping effect persists in the scientific community. Here, the spin pumping phenomenon is investigated in Galfenol (FeGa) thin films by systematically varying the thickness of the heavy metallic Ta underlayer (UL). The films exhibit soft magnetic properties with a bcc‐phase and a notably low Gilbert damping is obtained for FeGa on Si (100). The precessional magnetization dynamics of Ta/FeGa films are explored using the time‐resolved magneto‐optical Kerr effect technique, revealing the presence of a resonant Kittel mode and additional strain‐induced modes. The lowest value of effective Gilbert damping in Ta/FeGa is obtained as ∼0.015, which rises by ∼65% as the thickness of UL increases. Spin pumping and two‐magnon scattering mechanisms are validated using a ballistic spin transport model. An overall effective spin mixing conductance value of ∼5.48 × 1015 cm−2 is found, which is the highest value ever reported in magnetostrictive Galfenol films. Additionally, micromagnetic simulations are explored to understand the effect of tilted magnetic anisotropy on the formation of magnetic modes in these films. These findings in FeGa films establish it as an effective spin source material and offer innovative ideas to control spin‐wave propagation and diverse applications in straintronics.