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Pan, Yucheng; Sang, Min; Duan, Shilong; Li, Zimu; Zhang, Zhentao; Liu, Shuai; Wu, Jianpeng; Chen, Hong; Hu, Yuan; Gong, Xinglong

doi: 10.1002/smll.202500493pmid: 40135349

The ubiquitous mechanical and thermal damage in extreme environments puts new demands on protective equipment. At the same time, with the continuous development of electronic equipment, electromagnetic hazards and information leakage risks are increasing, so equipment with force/thermal/magnetic protection performance needs to be developed urgently. Herein, a shear thickened composite aerogel (MS) with host–guest structure is developed by a two‐step reinforcement process involving unidirectional freeze casting and ultrasonic assisted penetration of shear thickening fluid (STF). An interweaved skeleton is established by introducing MXene nanosheets, thus improving the structure stability. Moreover, the MS composite with further reinforced structure is obtained through the synergetic enhancement of STF, which achieves high compressive strength (570 kPa) and superior impact resistance (80% impact dissipation). Meanwhile, MS composite shows reliable heat insulation and flame retardant ability, and the total heat release is as low as 4.8 kJ g−1. Furthermore, MS demonstrates an efficient shielding performance of 45.5 dB at an extremely low MXene load of 0.43 wt%. As a result, this functionally integrated composite is proving to be a competitive candidate for resistance to impact damage, thermal threats and electromagnetic interference hazards in complex environments.

Xie, Fengting; Wu, Ziyang; Yang, Jianping

doi: 10.1002/smll.202500833pmid: 40159784

Electrochemical nitrate reduction (NO3RR) offers a sustainable approach to mitigating nitrogen pollution while enabling the resourceful conversion of nitrate (NO3−) into ammonia (NH3), nitrogen gas (N2), and value‐added chemicals such as urea. Copper (Cu)‐based catalysts, with their versatile catalytic properties and cost‐effectiveness, have emerged as pivotal materials in advancing NO3RR. This review systematically summarizes recent progress in Cu‐based catalysts for NO3RR, focusing on their catalytic mechanisms, tuning strategies, and applications across diverse product pathways. The intrinsic self‐reconstruction behavior and synergistic effects of Cu‐based catalysts are elucidated alongside advanced in situ characterization techniques that reveal dynamic structural evolution and intermediate interactions during reactions. We comprehensively discuss the performance of Cu‐based catalysts in steering NO3RR toward NH3 or N2 production, emphasizing the role of catalyst design (e.g., single atoms, alloys, oxides, hydroxides) in enhancing selectivity and efficiency. Furthermore, the multifunctionality of Cu catalysts is exemplified through carbon–nitrogen (C–N) coupling reactions, where reactive nitrogen intermediates are valorized into urea. Key challenges and future directions are outlined to guide the rational design of Cu‐based systems for efficient electrochemical nitrogen cycling.

Zhang, Xuanwei; Matsuo, Ryu; Yahano, Yusuke; Nishida, Jun; Namura, Kyoko; Suzuki, Motofumi

doi: 10.1002/smll.202408979pmid: 40231610

Microbubbles in liquids dynamically change their volumes through iterative vaporization and gas compression, driving highly localized (≈5 µm) and rapidly oscillating (≈1 MHz) flows. In contrast to an isolated bubble, closely spaced multiple bubbles can potentially induce not only stronger flows but also more complex flow profiles that are spatially and temporally regulated. However, precise on‐demand control of bubble distance and the associated interactions between bubbles has remained elusive, limiting their applications in microfluidics. This study demonstrates the induction of two laser‐induced microbubbles with configurable separations ranging from 14 to 92 µm with 1 µm precision. These microbubbles self‐oscillating at sub‐MHz frequencies are generated via photothermal heating, and their dynamics are captured in real‐time using a high‐speed camera. When the bubbles are in proximity (< 50 µm), their oscillation profiles are in stark contrast to those of an isolated bubble, exhibiting hybridized in‐phase and anti‐phase vibrations. The distance‐dependent evolution of the coupled oscillation frequency, ranging from 0.5 to 0.8 MHz is quantitatively reproduced, using an extended Rayleigh–Plesset equation that accounts for pressure interactions. The findings pave the way for leveraging multiple microbubble arrays to generate complex yet well‐regulated spatiotemporal flows previously unattainable in microfluidics.

Han, Qi; Li, Jiaqi; Deng, Hao; Shi, Sirong; Zhou, Mi; Cai, Xiaoxiao; Chen, Yu; Lin, Yunfeng

doi: 10.1002/smll.202570159pmid: N/A

Dai, Xingjian; Li, Yingfeng; Li, Hongjia; Zhou, Weiling; Xu, Xiaopeng; Deng, Min; Liao, Chentong; Peng, Qiang

doi: 10.1002/smll.202411457pmid: 40135346

Heterojunction interfaces play a crucial role in charge carrier transport, influencing the overall photovoltaic performance of organic solar cells (OSCs). Despite the importance, advancements in interfacial engineering, especially in optimizing the microstructure and nanomorphology, have not kept pace with research on photoactive layers. In the study, a strategy is explored to control the self‐assembly growth of alcohol‐soluble Me‐4PACz (4P) used as a hole transport layer (HTL) in OSCs. The surface architecture is modified of inorganic Co salts via Cu doping and UV‐ozone treatments, creating a smooth top surface with an increased Co3+/Co2+ ratio and hydroxyl groups. This meticulous design fine‐tuned the assembly behavior of self‐assembled molecules, resulting in the transition from spherical aggregates to a more uniform worm‐like morphology. Additionally, the electrical and optical properties are optimized to passivate surface defects and enhance the wettability of organic solvents, leading to improved hole extraction and reduced interfacial charge carrier recombination losses. Consequently, an OSC with Cu‐Co/4P as the HTL exhibited the highest power conversion efficiency of 20.42% (certified 20.20%). The characteristic universality and stability make the Cu‐Co/4P HTL a potential candidate for widespread applications, particularly in providing rationalized guidance to further enhance the performance of OSCs.

Moss, Genevieve C.; Binninger, Tobias; Rajan, Ziba S. H. S.; Itota, Bamato J.; Kooyman, Patricia J.; Susac, Darija; Mohamed, Rhiyaad

doi: 10.1002/smll.202412237pmid: 40159796

Iridium oxides are the state‐of‐the‐art oxygen evolution reaction (OER) electrocatalysts in proton‐exchange‐membrane water electrolyzers (PEMWEs), but their high cost and scarcity necessitate improved utilization. Crystalline rutile‐type iridium dioxide (IrO2) offers superior stability under acidic OER conditions compared to amorphous iridium oxide (IrOx). However, the higher synthesis temperatures required for crystalline phase formation result in lower OER activity due to the loss in active surface area. Herein, a novel perchlorate fusion–hydrothermal (PFHT) synthesis method to produce nano‐crystalline rutile‐type IrO2 with enhanced OER performance is presented. This low‐temperature approach involves calcination at a mild temperature (300 °C) in the presence of a strong oxidizing agent, sodium perchlorate (NaClO4), followed by hydrothermal treatment at 180 °C, yielding small (≈2 nm) rutile‐type IrO2 nanoparticles with high mass‐specific OER activity, achieving 95 A gIr−1 at 1.525 VRHE in ex situ glass‐cell testing. Most importantly, the catalyst displays superior stability under harsh accelerated stress test conditions compared to commercial iridium oxides. The exceptional activity of the catalyst is confirmed with in situ PEMWE single‐cell evaluations. This demonstrates that the PFHT synthesis method leverages the superior intrinsic properties of nano‐crystalline IrO2, effectively overcoming the typical trade‐offs between OER activity and catalyst stability.

Yu, Jiahao; Kou, Yong; Lei, Hongbing; Lu, Qiangqiang; Xiao, Lei; Yang, Hongyu; Xu, Xuran; Yang, Junqing; Jiang, Wei; Hao, Gazi

doi: 10.1002/smll.202500967pmid: 40150993

Ammonium perchlorate (AP) plays an important role in solid propellants because of its high specific impulse, high energy density and low cost. However, the excellent performance cannot conceal the many shortcomings of AP, and the problems of non‐concentrated exothermic, high sensitivity and hygroscopicity still seriously impede its application in solid propellants. In this study, the solvent evaporation method is used to directionally modify the order of the cupric oxide (CuO) and fluororubber (F2603) shell layers so as to obtain AP‐based composites with different core‐shell structures. The interlayer binding energies of the composites with different structures are explored by theoretical calculations, and it is demonstrated that AP‐based composites have excellent stability. In addition, CuO with valence‐band holes not only reduces the peak temperature of the high temperature decomposition of AP (440.4 to 354.5 °C), but also enhances its combustion properties by undergoing thermite reaction with Al. Furthermore, the excellent hydrophobicity and barrier properties of F2603 greatly strengthened the hydrophobicity and mechanical properties of the AP‐based composites and reduced their sensitivity. In summary, the core‐shelled structures AP‐based composites prepared by this strategy possessed 5‐in‐1 excellent properties, which provided a new idea for targeted modulation of the properties of energetic materials.

Halseth, Troy A.; Mujeeb, Anzar A.; Liu, Lisha; Banerjee, Kaushik; Lang, Nigel; Hollon, Todd; Yu, Minzhi; Vander Roest, Mark; Mei, Ling; He, Hongliang; Sheth, Maya; Castro, Maria G.; Schwendeman, Anna

doi: 10.1002/smll.202307097pmid: 40249282

Glioblastoma multiforme (GBM) is a highly aggressive primary brain tumor with a 5‐year survival rate of 7%. Previous studies have shown that GBM tumors have a reduced capacity to produce cholesterol and instead depend on the uptake of cholesterol produced by astrocytes. To target cholesterol metabolism to induce cancer cell death, synthetic high‐density lipoprotein (sHDL) nanodiscs delivering Liver‐X‐Receptor (LXR) agonists and CpG oligonucleotides for targeting GBM are investigated. LXR agonists synergize with sHDL nanodiscs by increasing the expression of the ABCA1 cholesterol efflux transporter, resulting in further depletion of cholesterol reserves within tumors, and CpG oligonucleotides are established adjuvants used in cancer immunotherapy that work through the toll‐like receptor 9 pathway. In the present study, treatment with GW‐CpG‐sHDL nanodiscs increases the expression of cholesterol efflux transporters on murine GL261 cells leading to enhanced cholesterol removal. Experiments in GL261‐tumor‐bearing mice reveal combining GW‐CpG‐sHDL nanodiscs with radiation (IR) therapy significantly increases median survival compared to GW‐CpG‐sHDL or IR alone. Furthermore, 66% of long‐term survivors from the GW‐CpG‐sHDL +IR treatment group show no tumor tissue when rechallenged.

Lee, Jin Ah; Lee, In Suh; Kang, Dayoung; Kim, Nayeon; Kim, Jigeon; Baek, Se‐Woong; Kim, Younghoon

doi: 10.1002/smll.202412420pmid: 40159846

Eco‐friendly Ag2Te colloidal quantum dots (CQDs) have emerged as promising candidates for shortwave infrared (SWIR) optoelectronic applications owing to their size‐tunable bandgaps with high optical properties. However, conventional synthesis methods relying on high temperatures and long reaction times yield low‐quality Ag2Te CQDs because of their low chemical stability, resulting in decomposition under synthetic conditions and, thus, a non‐uniform size distribution. Here, chemical reactivity‐controlled synthesis is presented to regulate the crystal size and bandgap of Ag2Te CQDs. This involves adjusting the concentration and type of ligands, as well as the precursor ratio. The rapid termination of the reaction in this method prevents Ag2Te CQD decomposition, yielding monodisperse CQDs with a 1.66 peak‐to‐valley ratio at the first exciton absorption peak (≈1440 nm) and enabling absorption and emission in the 1100−1600 nm range. Furthermore, polar antisolvents in the purification process cause surface ligand removal from Ag2Te CQDs, resulting in surface defects and CQD aggregation. To mitigate these issues by enhancing their chemical stability, core/shell‐type Ag2Te/Ag2S CQDs are synthesized. The photoluminescence (PL) intensity of Ag2Te/Ag2S CQDs significantly increased fivefold compared to Ag2Te core CQDs, and after purification, their size distribution remained uniform with preserved PL intensity. This is attributed to a significant reduction in surface defects. Consequently, the Ag2Te/Ag2S CQD‐based SWIR photodetector exhibits a high external quantum efficiency of 8.4% and a specific detectivity of 1.1 × 1011 Jones at 1550 nm, with a fast response time of 38 ns.

Celi, Nuoer; Gong, De; Cai, Jun; Tang, Tan; Xu, Ye; Zhang, Deyuan

doi: 10.1002/smll.202407585pmid: 39806837

Magnetic microrobots are significant platforms for targeted drug delivery, among which sperm‐inspired types have attracted much attention due to their flexible undulation. However, mass production of sperm‐like soft magnetic microrobots with high‐speed propulsion is still challenging due to the need of more reasonable structure design and facile fabrication. Herein, a novel strategy is proposed for large‐scale preparation of microalgae‐based soft microrobots with a fully magnetic head‐to‐tail structure, called AlgaeSperm with robust propulsion and chemo‐photothermal performance. This approach deposited Pd@Au nanoparticles (NPs) inside chlorella cells, which are further coated with Fe3O4 NPs and polydopamine layers to form the magnetic heads. Then, flexible flagella are grafted via magnetic assembly of Fe3O4@PVP NPs to construct the final AlgaeSperm. Under precessing magnetic fields, the AlgaeSperms can achieve a forward velocity up to 2.3 body length/s, the highest among sperm‐like magnetic microrobots to the best of the knowledge. Besides, their flexible maneuverability in a swarm is also verified. In vitro anti‐cancer experiments are conducted after loading doxorubicin (DOX) to confirm their excellent targeted chemo‐photothermal performance. This work offers a significant paradigm for constructing sperm‐like soft magnetic microrobots with great potential for targeted tumor treatment.