Kinetic Insight into the Formation of Physically Robust Molecular Network in Cellulose HydrogelsChen, Shi‐Peng; Zhu, Jin‐Long; Yang, Hongli; Zhou, Shengyang; Zhong, Gan‐Ji; Huang, Hua‐Dong; Li, Zhong‐Ming
doi: 10.1002/smll.202503486pmid: 40346962
Sol‐gel method unlocks the enormous potential of utilizing abundant and renewable cellulose resources. However, the molecular‐level structural evolution during the cellulose gelation process is less well understood, bringing challenges for achieving high performance of cellulose hydrogels by regulating their molecular network. Herein, a fascinating journey is unveiled through time‐resolved in situ techniques for the evolution of the hierarchical structure of cellulose from micro to molecular scale during the gelation process. The two‐regime gelation mechanism of cellulose is proposed. Unexpectedly, it is discovered that the polarity of anti‐solvents could effectively control the gelation kinetics and manipulate the molecular network of cellulose hydrogels. As a result, the performance of cellulose hydrogels can be purposefully customized, which are either robust and elastic, or tough and high‐damping. Understanding the gelation mechanism of cellulose and its structural evolution kinetics unlocks the pathways to exceptional performance and multifunctionality, which will foster potential advances in sustainable cellulose‐based hydrogels.
Molecular Tuning of Pyrene‐Based Conjugated Porous Polymers for Enhanced Photocatalytic Hydrogen ProductionZeng, Xinyu; Meng, Kai; Wang, Wang; Zhang, Jianjun; Cheng, Bei; Zhang, Song; Luo, Guoqiang; Yu, Jiaguo; Cao, Shaowen
doi: 10.1002/smll.202500130pmid: 40341901
Conjugated porous polymers (CPPs) have emerged as promising candidates for photocatalytic H2 production (PHP) in recent years due to their structural diversity, tunable electronic properties, and high specific surface area. Herein, three CPPs are synthesized by the Suzuki coupling reaction for photocatalytic H2O splitting to produce H2. Through molecular tuning strategies, the π‐conjugation degree of the CPPs is adjusted, significantly impacting the charge separation and transfer efficiency of the photocatalysts as well as their light‐harvesting ability. The optimal photocatalyst, namely PyDF, shows a high photocatalytic H2 evolution rate of 12.8 mmol g−1 h−1 with a large number of continuous visible bubbles, which is up to five times higher than its counterparts. Advanced characterization techniques, including photo‐irradiated Kelvin probe force microscopy (KPFM) and femtosecond transient absorption (fs‐TA) spectroscopy, together with theoretical calculations, reveal that the PyDF with a smaller dihedral angle has much‐improved π‐conjugation degree, resulting in higher charge separation and transfer efficiency. This work provides a new perspective for the application of CPPs in the PHP and emphasizes the importance of modulation of the π‐conjugation degree.
The Full‐Graphdiyne‐Based Fast‐Charging Aqueous Zinc Ion Battery Toward Synergistically Boosted Capacity and Long LifespanXiong, Zecheng; Sun, Hao; Su, Wei; Jin, Weiyue; Liu, Hongye; Huang, Yang; Liu, Huibiao
doi: 10.1002/smll.202502191pmid: 40331499
The practical application of rechargeable aqueous zinc ion batteries (AZIBs) is severely hindered by their poor stability, sluggish kinetics, and limited specific capacity. Based on the synergetic effect of trifluoro‐substituted graphdiyne (3F‐GDY), a full‐graphdiyne‐based AZIB is designed that achieves simultaneous regulation of cathodic and anodic electrochemical performance with enhanced lifespan, capacity, and fast‐charging property. 3F‐GDY@Zn||3F‐GDY@NVO full cell exhibits specific capacity of 486.0 mA h g−1 at current density of 0.1 A g−1 with stable cycling performance of over 4000 cycles at 1 A g−1, 7000 cycles at 5 A g−1 and 10000 cycles at 10 A g−1.The synergetic effects of 3F‐GDY for AZIBs are further investigated via electrochemical and ex situ characterization techniques, as 3F‐GDY possesses porous structure, strong interaction between F atoms and zinc ions, and robust strength. These results bring new perspectives to the fabrication of high‐performance AZIBs.
NIR‐Induced Photoswitching Hybrid DNA Nanoconstruct‐Based Drug Delivery System for Spatiotemporal Control of Stem Cell FatePongkulapa, Thanapat; Yum, Ji Hye; McLoughlin, Callan D.; Conklin, Brandon; Kumagai, Tomotaka; Goldston, Li Ling; Sugiyama, Hiroshi; Park, Soyoung; Lee, Ki‐Bum
doi: 10.1002/smll.202409530pmid: 40007062
Precise spatiotemporal control of drug delivery is extremely valuable for regulating stem cell fate, particularly in stem cell differentiation. A novel near‐infrared (NIR)‐mediated spatiotemporal delivery system is reported combining photo‐switchable arylazopyrazole (AAP)‐containing DNA strands and upconversion nanoparticles (UCNPs). This nano‐drug delivery system (NDDS) enables precise modulation of DNA duplex structures in response to NIR stimuli, overcoming the limitations of traditional UV‐responsive systems. AAP derivatives with enhanced photoswitching efficiency (≈98%) and significantly improved cis‐form stability are engineered. The successful delivery of curcumin, a neurogenic compound with an affinity for the minor groove of DNA, to human neural stem cells (NSCs) is achieved using UCNP‐DNA‐AAP constructs. Upon 980 nm NIR light exposure, UCNPs efficiently up‐converted NIR to UV light, triggering AAP photoisomerization and DNA dissociation, thus releasing curcumin. This approach enabled efficient spatiotemporal control over NSC differentiation while facilitating neuroprotection. Immunofluorescence and gene expression analyses demonstrated enhanced neuronal mRNA levels and neurite outgrowth in treated cells. In short, the NIR‐mediated photo‐switchable NDDS offers a precise and innovative approach to control stem cell fate, enabling spatiotemporal regulation of cellular processes. This technology has significant potential applications in nanomedicine and neuroscience, where precise drug delivery is crucial for targeted neural interventions.
Understanding Volatile Electrical Switching in hBN Nanodevices by Fully Optical Operando InvestigationKelly, Dawn M.; Symonowicz, Joanna; Stewart, J. Callum; Hofmann, Stephan; Di Martino, Giuliana
doi: 10.1002/smll.202410569pmid: 40357810
Memristors based on 2D materials have emerged as promising candidates for use in artificial synaptic devices and energy‐efficient neuromorphic computing. Limited understanding of the fundamental switching mechanisms hinders device optimization and stalls commercialization. Conventional analysis techniques are often destructive, and only offer a static characterization of the device after electrical cycling, providing limited insights into switching dynamics. In this study, an operando approach utilizing plasmon enhancement of optical signals is used to investigate a two‐terminal vertical device based on monolayer hexagonal boron nitride. Real‐time photoluminescence and dark‐field scattering measurements reveal that conductive filaments (CFs) form through the migration of metallic ions from the electrode. The modification of a photoluminescence signal near 620 nm and a redshift of dark‐field scattering indicating a refractive index change of roughly 1 are detected when voltage is applied across the nanodevice. These optical changes are interpreted to show that this CF formation is mediated by point defect structures. This highlights the crucial role of defects in the switching dynamics. This finding resolves the ongoing debate in the literature about the mechanism of CF formation and paves the way for defect engineering as a step‐changing pathway to the optimization of these devices.
Tunable Charge Distribution in Self‐Supported NiCoP Through V and Mo Incorporation for Efficient Hydrogen Evolution in all pH Ranges and Alkaline SeawaterBagaria, Tanu; Borgohain, Taranga; Jadhav, Swati; Das, Tisita; Debnath, Bharati
doi: 10.1002/smll.202503368pmid: 40321037
Developing electrocatalysts with high activity and durability remains a key challenge in water electrolysis, essential for advancing sustainable hydrogen fuel production. Efficient electrocatalysts capable of functioning across diverse pH conditions and in alkaline seawater for hydrogen evolution reactions (HER) are crucial for the future of clean energy. In this study, a dual incorporation of vanadium (V) and molybdenum (Mo) into NiCoP [V, M (x,y)‐NCP] catalyst is successfully fabricated via electrodeposition, offering an effective method for enhancing HER activity. Exhibiting low impedance and a high electrochemically active surface area, the material achieved overpotentials of 24 mV in 0.5 m H2SO4, 85 mV in 1 m PBS, and 32 mV in 1 m KOH at 10 mA cm−2. Impressively, V, M (3,6)‐NCP demonstrated excellent electrocatalytic performance in alkaline seawater, achieving 41 mV at 10 mA cm−2. The catalyst exhibited remarkable corrosion resistance, maintaining stable performance for over 100 h. Theoretical calculations revealed that Mo and V incorporation into NiCoP enhances electron transfer efficiency by modifying the local electronic structure, promoting the HER process effectively. These findings highlight the significant impact of dual metal incorporation in enhancing HER technology, offering a straightforward, efficient, and cost‐effective method for developing advanced electrocatalysts for diverse energy applications.