1D metal‐oxide nanotube (NT) structures have attracted considerable attention for applications in chemical sensors due to their high surface area and unique chemical and physical properties. ...Moreover, bimodal pores, i.e., meso‐ and macro‐sized pores, which are formed on the shell of NTs, can further facilitate gas penetration into the sensing layers, leading to much improved sensing properties. However, thin‐walled NTs with bimodal pore distribution have been rarely fabricated due to the limitations of synthetic methods. Here, Ostwald ripening‐driven electrospinning combined with sacrificial templating route using polystyrene (PS) colloid and bioinspired protein is firstly proposed for producing both bi‐modal pores and catalyst‐loaded thin‐walled SnO2 NTs. Homogeneous catalyst loading on porous SnO2 NTs is achieved by the protein cage that contains catalysts and PS colloids and protein shells are thermally decomposed during calcination of electrospun fibers, resulting in the creation of dual‐sized pores on NTs. Pt catalyst decorated porous SnO2 NTs (Pt‐PS_SnO2 NTs) show exceptionally high acetone gas response, superior selectivity against other interfering gases, and very low limit of detection (10 ppb) to simulated diabetic acetone molecules. More importantly, sensor arrays assembled with developed porous SnO2 NTs enable the direct distinction between the simulated diabetic breath and normal breath from healthy people.
Highly mesoporous SnO2 nanotubes (NTs) functionalized with large pores and bioinspired catalysts (Pt‐PS_SnO2 NTs) are simply synthesized as an ideal nanostructure of sensing layers by using biotemplating route and diffusion of SnO2 effect. Pt‐PS_SnO2 NTs exhibit dramatically enhanced acetone sensing performance; especially, they can clearly distinguish the exhaled breath of healthy people and diabetics.
Abstract
Conductive metal-organic framework (C-MOF) thin-films have a wide variety of potential applications in the field of electronics, sensors, and energy devices. The immobilization of various ...functional species within the pores of C-MOFs can further improve the performance and extend the potential applications of C-MOFs thin films. However, developing facile and scalable synthesis of high quality ultra-thin C-MOFs while simultaneously immobilizing functional species within the MOF pores remains challenging. Here, we develop microfluidic channel-embedded solution-shearing (MiCS) for ultra-fast (≤5 mm/s) and large-area synthesis of high quality nanocatalyst-embedded C-MOF thin films with thickness controllability down to tens of nanometers. The MiCS method synthesizes nanoscopic catalyst-embedded C-MOF particles within the microfluidic channels, and simultaneously grows catalyst-embedded C-MOF thin-film uniformly over a large area using solution shearing. The thin film displays high nitrogen dioxide (NO
2
) sensing properties at room temperature in air amongst two-dimensional materials, owing to the high surface area and porosity of the ultra-thin C-MOFs, and the catalytic activity of the nanoscopic catalysts embedded in the C-MOFs. Therefore, our method,
i.e
. MiCS, can provide an efficient way to fabricate highly active and conductive porous materials for various applications.
Alloys are recently receiving considerable attention in the community of rechargeable batteries as possible alternatives to carbonaceous negative electrodes; however, challenges remain for the ...practical utilization of these materials. Herein, we report the synthesis of germanium-zinc alloy nanofibers through electrospinning and a subsequent calcination step. Evidenced by in situ transmission electron microscopy and electrochemical impedance spectroscopy characterizations, this one-dimensional design possesses unique structures. Both germanium and zinc atoms are homogenously distributed allowing for outstanding electronic conductivity and high available capacity for lithium storage. The as-prepared materials present high rate capability (capacity of ~ 50% at 20 C compared to that at 0.2 C-rate) and cycle retention (73% at 3.0 C-rate) with a retaining capacity of 546 mAh g
even after 1000 cycles. When assembled in a full cell, high energy density can be maintained during 400 cycles, which indicates that the current material has the potential to be used in a large-scale energy storage system.
It has been reported that neutrophil extracellular traps (NETs) play important roles in non-infectious diseases. In ischemic stroke, neutrophils infiltrate damaged brain tissue soon after injury and ...aggravate inflammation. Using a rat permanent MCAO model, we showed citrullinated histone H3
(CitH3, a marker of NETosis) induction in neutrophils in leptomeninges and in peripheral blood soon after MCAO. Entry of CitH3
cells occurred through leptomeninges after 6 h of MCAO and these cells were observed in cerebral cortex from 12 h and subsequently in striatum. It is interesting to note that CitH3
induction began in circulating neutrophils before they migrated to brain parenchyma and they were detected as intact or lysed form. High mobility group box 1 (HMGB1), a danger associated molecular pattern (DAMP) molecule, was accumulated massively in serum after permanent MCAO and plays a critical role in CitH3 inductions in neutrophils in brain parenchyma and in peripheral blood. Both the all-thiol and disulfide types of HMGB1 induced CitH3 via their specific receptors, CXCR4 and TLR4, respectively. Importantly, HMGB1 not only induced NETosis but was included as a part of the extruded NETs, and contribute to NETosis-mediated neuronal death. Therefore, it would appear a vicious cycle exists between neuronal cell death and NETosis and HMGB1 mediates detrimental effects exerted by this cycle. When NETosis was suppressed by a PAD inhibitor in MCAO animals, delayed immune cell infiltrations were markedly suppressed and damages in blood vessels were significantly mitigated. The study shows NETosis with the involvement of HMGB1 as a mediator in a vicious cycle aggravates inflammation and subsequent damage in the ischemic brain.
Single‐atom catalysts (SACs) supported on inorganic materials have attracted much attention in numerous research fields for their high catalytic performance. However, such SACs have been limited by ...the low metal loading, especially on different types of inorganic supports. Herein, a general approach is presented for preparing SACs on metallic, metal oxide, and perovskite nanosheet (NS) supports to reach a high metal loading of up to 3.94 wt%, by utilizing N‐doped graphene as a sacrificial template that spatially confines the single atoms (SAs). Specifically, the target support material precursors are adsorbed onto the SAs‐stabilized sacrificial template, followed by subsequent heat treatment to transfer the SAs to the support material and to remove the graphene layer. Pt SAs on oxide support exhibits little to no aggregation throughout >10 000 min of annealing at 275 °C, demonstrating high thermal stability, as also supported by ex situ post‐anneal electron microscopy and X‐ray absorption fine structure studies. As a proof‐of‐concept, Pt SACs on SnO2 NSs exhibit high catalytic activity toward chemiresistive sensing of acetone gas (response = 95.4 at 10 ppm, 7.6‐fold enhancement compared with pristine SnO2 NSs) and unprecedented stability under highly humid conditions (27.4% response deterioration at 95% relative humidity).
A general strategy is developed to fabricate various types of inorganic nanosheets (NSs) with high‐loading single‐atom catalysts (SACs). N‐doped graphene sacrificial template loaded with high‐loading Pt SACs can successfully transfer the SACs onto NSs‐structured support materials composed of binary and ternary metal oxides and metal. The SACs possess high thermal stability, owing to strong covalent metal–support interactions.
Light‐activated chemiresistors offer a powerful approach to achieving lower‐temperature gas sensing with unprecedented sensitivities. However, an incomplete understanding of how photoexcited charge ...carriers enhance sensitivity obstructs the rational design of high‐performance sensors, impeding the practical utilization under commonly accessible light sources instead of ultraviolet or higher‐energy sources. Here, a rational approach is presented to modulate the electronic properties of the parent metal oxide phase, exemplified by this model system of Bi‐doped In2O3 nanofibers decorated with Au nanoparticles (NPs) that exhibit superior NO2 sensing performance. Bi doping introduces mid‐gap energy levels into In2O3, promoting photoactivation even under visible blue light. Additionally, green‐absorbing plasmonic Au NPs facilitate electron transfer across the heterojunction, extending the photoactive region toward the green light. It is revealed that the direct involvement of photogenerated charge carriers in gas adsorption and desorption processes is pivotal for enhancing gas sensing performance. Owing to the synergistic interplay between the Bi dopants and the Au NPs, the Au‐BixIn2‐xO3 (x = 0.04) sensing layers attain impressive response values (Rg/Ra = 104 at 0.6 ppm NO2) under green light illumination and demonstrate practical viability through evaluation under simulated mixed‐light conditions, all of which significantly outperforms previously reported visible light‐activated NO2 sensors.
The role of interface chemistry of Au‐BixIn2‐xO3 in green‐light‐activated NO2 sensing is systematically investigated. The synergistic interplay between Bi dopants and Au nanoparticles is the key to photosensitizing In2O3 to visible light, significantly reinforcing sensitivity and reversibility at ambient conditions. This meticulous study provides an understanding of the photoactivation mechanism mediated by two dissimilar photosensitizers.
Rational design and massive production of bifunctional catalysts with fast oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics are critical to the realization of highly ...efficient lithium–oxygen (Li–O2) batteries. Here, we first exploit two types of double-walled RuO2 and Mn2O3 composite fibers, i.e., (i) phase separated RuO2/Mn2O3 fiber-in-tube (RM-FIT) and (ii) multicomposite RuO2/Mn2O3 tube-in-tube (RM-TIT), by controlling ramping rate during electrospinning process. Both RM-FIT and RM-TIT exhibited excellent bifunctional electrocatalytic activities in alkaline media. The air electrodes using RM-FIT and RM-TIT showed enhanced overpotential characteristics and stable cyclability over 100 cycles in the Li–O2 cells, demonstrating high potential as efficient OER and ORR catalysts.
In the quest for materials sustainability for grid‐scale applications, graphene quantum dot (GQD), prepared via eco‐efficient processes, is one of the promising graphitic‐organic matters that have ...the potential to provide greener solutions for replacing metal‐based battery electrodes. However, the utilization of GQDs as electroactive materials has been limited; their redox behaviors associated with the electronic bandgap property from the sp2 carbon subdomains, surrounded by functional groups, are yet to be understood. Here, the experimental realization of a subdomained GQD‐based anode with stable cyclability over 1000 cycles, combined with theoretical calculations, enables a better understanding of the decisive impact of controlled redox site distributions on battery performance. The GQDs are further employed in cathode as a platform for full utilization of inherent electrochemical activity of bio‐inspired redox‐active organic motifs, phenoxazine. Using the GQD‐derived anode and cathode, an all‐GQD battery achieves a high energy density of 290 Wh kgcathode−1 (160 Wh kgcathode+anode−1), demonstrating an effective way to improve reaction reversibility and energy density of sustainable, metal‐free batteries.
An all‐graphene quantum dot (GQD)‐derived battery is proposed as a novel platform for sustainable energy storage. Previously unobservable redox behaviors of functional groups in subdomained GQDs are explored to understand the effect of spatially controlled redox sites on electrochemical activity and reversibility. This study also provides a promising method to expedite the practical use of naturally abundant organic redoxophores.
Practical sensing applications such as real‐time safety alerts and clinical diagnoses require sensor devices to differentiate between various target molecules with high sensitivity and selectivity, ...yet conventional devices such as oxide‐based chemo‐resistive sensors and metal‐based surface‐enhanced Raman spectroscopy (SERS) sensors usually do not satisfy such requirements. Here, a label‐free, chemo‐resistive/SERS multimodal sensor based on a systematically assembled 3D cross‐point multifunctional nanoarchitecture (3D‐CMA), which has unusually strong enhancements in both “chemo‐resistive” and “SERS” sensing characteristics is introduced. 3D‐CMA combines several sensing mechanisms and sensing elements via 3D integration of semiconducting SnO2 nanowire frameworks and dual‐functioning Au metallic nanoparticles. It is shown that the multimodal sensor can successfully estimate mixed‐gas compositions selectively and quantitatively at the sub‐100 ppm level, even for mixtures of gaseous aromatic compounds (nitrobenzene and toluene) with very similar molecular structures. This is enabled by combined chemo‐resistive and SERS multimodal sensing providing complementary information.
Synergistic electrical and optical multimodal sensing by 3D nanoarchitectures for label‐free gas detection is reported.
The increase of surface area and the functionalization of catalyst are crucial to development of high-performance semiconductor metal oxide (SMO) based chemiresistive gas sensors. Herein, nanoscale ...catalyst loaded Co3O4 hollow nanocages (HNCs) by using metal–organic framework (MOF) templates have been developed as a new sensing platform. Nanoscale Pd nanoparticles (NPs) were easily loaded on the cavity of Co based zeolite imidazole framework (ZIF-67). The porous structure of ZIF-67 can restrict the size of Pd NPs (2–3 nm) and separate Pd NPs from each other. Subsequently, the calcination of Pd loaded ZIF-67 produced the catalytic PdO NPs functionalized Co3O4 HNCs (PdO–Co3O4 HNCs). The ultrasmall PdO NPs (3–4 nm) are well-distributed in the wall of Co3O4 HNCs, the unique structure of which can provide high surface area and high catalytic activity. As a result, the PdO–Co3O4 HNCs exhibited improved acetone sensing response (R gas/R air = 2.51–5 ppm) compared to PdO–Co3O4 powders (R gas/R air = 1.98), Co3O4 HNCs (R gas/R air = 1.96), and Co3O4 powders (R gas/R air = 1.45). In addition, the PdO–Co3O4 HNCs showed high acetone selectivity against other interfering gases. Moreover, the sensor array clearly distinguished simulated exhaled breath of diabetics from healthy people’s breath. These results confirmed the novel synthesis of MOF templated nanoscale catalyst loaded SMO HNCs for high performance gas sensors.
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