Drought and nitrogen (N) deposition are major threats to global forests under climate change. However, investigation into how dioecious woody species acclimate to drought and N deposition and how ...this is influenced by gender has, so far, been unexplored. We examined the phenotypic and physiological changes in Salix myrtillacea females and males under 60 d drought, and wet N deposition on leaves’ treatments. Drought inhibited their growth by limiting water acquisition, photosynthesis, and increasing oxidative stress, especially in males. However, females exhibited greater drought resistance than males due to their better water acquisition ability and instantaneous water use efficiency (WUEleaf), higher foliar abscisic acid (ABA) and auxin (IAA) levels and greater antioxidase activities. N deposition increased foliar ABA, H2O2 accumulation, and reduced N distribution to the leaves, causing restricted photosynthesis and aerial growth in males. Interestingly, N deposition improved biomass accumulation in both the genders under drought, with greater positive effects on drought-stressed males by increasing their radial growth and causing greater N distribution to the leaves, increased foliar IAA and reduced oxidative stress. Regardless, S. myrtillacea females still showed better growth and drought resistance than males under both drought and N deposition. The females’ superior performance indicated that they are more appropriate for forestation, thus supporting the dominant gender’s selection in the afforestation of unisexual S. myrtillacea in drought and severe N deposition regions.
A flexible graphene oxide/Au nanoparticles (GO/AuNP) based fiber with high sensitivity and reproducibility for SERS sensing on a large scale using the self-assembly of liquid crystalline and wet ...spinning processes, which break the geometric limitations of the nanoscale of GO nanosheets and extend its properties to the macroscopic level.
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•Uniform encapsulation of AuNPs in GO fiber by electrostatic adsorption and liquid crystal self-assembly process.•Extending GO/AuNPs hybrids nanoscale properties to the macroscopic level to address geometric constraints.•SERS sensitivity of the sensor derives from the synergistic effect of CT resonance of GO and plasmonic coupling of AuNPs at vertical direction.•Flexible GO/AuNPs fiber allow sampling on the peel surface for rapid detection of thiram residues.
Graphene oxide has attracted wide interest for theoretical research and application exploration in surface enhancement Raman scattering (SERS). However, how to break the geometric limitations of the nanoscale and extend its properties to the macroscopic level remains an urgent problem. Here, we prepared flexible graphene oxide/Au nanoparticles (GO/AuNP) fibers with high sensitivity and reproducibility for SERS sensing using wet spinning method. Benefitting from the plasmonic coupling of GO/AuNP fibers in vertical direction and uniform adsorption of the target molecules, the limit of detection for fiber was as low as 5 × 10-11 M for rhodamine 6G (R6G) and crystal violet (CV) molecules. In addition, due to the optimal distribution of AuNP in the macroscopic assembly of GO/AuNP hybrid, the fiber substrates provided uniform and stable signals for both temporal (6 months) and spatial (RSD = 8.18 %) scales, exhibited excellent reliability and durability. Moreover, an ultra-low concentrations of the pesticide thiram residues could be rapidly traced by direct sampling from the apple peel with a sensitivity of 5 × 10-9 M, which is much lower than the residue limit set by the US environmental protection agency. We envision that this work could provide new insights into the large-scale and economical fabrication of high-performance flexible SERS sensors for real world applications.
A multifunctional MXene fiber was fabricated by incorporating MoO3-x nanobelts with abundant oxygen vacancies via wet spinning and coagulation process, where the produced fiber not only realized the ...substantially improvement of volumetric capacitances, but also demonstrated a low limit of detection for biomarkers in artificial sweat.
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•A multifunctional MXene/MoO3-x fiber was fabricated by wet spinning and coagulation methods.•Fiber realized an ultrahigh volumetric energy density after the addition of treated MoO3-x nanobelts.•Fiber demonstrated a low limit of detection for biomarkers in artificial sweat.•Fiber provided the potential applications in the next generation of wearable intelligent devices.
MXene fibers are expected to accelerate the sustainable development of intelligent era as multi-functional smart fibers. However, MXene fibers have serious obstacles when used for multi-functional applications. Here, we fabricated a multi-functional MXene fiber by incorporating MoO3-x nanobelts with abundant oxygen vacancies via wet spinning and defect engineering methods. Benefiting from the presence of abundant oxygen vacancies, the produced MXene/MoO3-x fibers not only provide more active sites to interact with electrolyte ions, but also substantially augment the rate capacities of fibers due to the enlarged distances between MXene flakes. Thus, the assembled fiber-based supercapacitor (SCs) realized high capacitance of 869.1F cm−3 at 0.5 A cm−3, good volumetric energy density of 77.3 mWh cm−3 at a power density of 204.8 mW cm−3 and long-term cycling stability along with 86.4 % capacity retention after 5000 cycles. Moreover, due to the narrowed bandgap of MoO3-x produced by defect engineering enhanced the charge transfer between the fiber and molecules, MXene/MoO3-x fiber also demonstrated a low limit of detection and reliable biomarkers detection in artificial sweat. These findings provide the potential application of MXene-based fibers in multi-functional devices.
Sensitive and rapid identification of volatile organic compounds (VOCs) at ppm level with complex composition is vital in various fields ranging from respiratory diagnosis to environmental safety. ...Herein, we demonstrate a SERS gas sensor with size-selective and multiplexed identification capabilities for VOCs by executing the pre-enrichment strategy. In particular, the macro-mesoporous structure of graphene aerogel and micropores of metal-organic frameworks (MOFs) significantly improved the enrichment capacity (1.68 mmol/g for toluene) of various VOCs near the plasmonic hotspots. On the other hand, molecular MOFs-based filters with different pore sizes could be realized by adjusting the ligands to exclude undesired interfering molecules in various detection environments. Combining these merits, graphene/AuNPs@ZIF-8 aerogel gas sensor exhibited outstanding label-free sensitivity (up to 0.1 ppm toluene) and high stability (RSD=14.8%, after 45 days storage at room temperature for 10 cycles) and allowed simultaneous identification of multiple VOCs in a single SERS measurement with high accuracy (error < 7.2%). We visualize that this work will tackle the dilemma between sensitivity and detection efficiency of gas sensors and will inspire the design of next-generation SERS technology for selective and multiplexed detection of VOCs.
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•A powerful graphene/AuNPs@ZIF-8 SERS gas sensor was fabricated.•Hierarchical pores greatly improve the enrichment efficiency of VOCs.•Pore size in sensor can be facilely adjusted for size-selective detection.•Sensor exhibited outstanding label-free sensitivity and high stability.
The preparation of high performance, low cost and recyclable adsorbents is very important to cope with the increasingly devastating water pollution. As a typical three-dimensional porous carbon ...material, carbon foam (CF) is expected to be a highly efficient adsorbent to wipe out organic dyes from wastewater. However, the uneven size distribution, and lack of adsorption sites signified by insufficient foaming process limit its wider application in the environmental field. Here, CF/carbon nanotubes/graphene oxide (CF/CNTs/GO) composites (adsorbents) were prepared by press-assisted foaming and carbonization methods using mesophase precursors of coal tar pitch and CNTs followed by impregnation of GO nanosheets. The results highlighted that the addition of CNTs facilitated improvement in pore distribution, porosities, and mechanical properties (20 MPa). After treating with GO nanosheets, the adsorption performances of CF/CNTs/GO adsorbents substantially improved due to the increased active sites in the CF/CNTs and the adsorption rate and capacity of methylene blue (MB) reached 73.1% and 146 mg/g respectively. Further, adsorption isotherms (Langmuir and Freundlich), thermodynamics, quasi-first order and quasi-second order kinetics and intraparticle diffusion models were employed to investigate the adsorption mechanism. This work provides a low-cost fabrication technique for the high-performance CF/CNTs/GO adsorbent and is expected to provide reference for application in the treatment of contaminated water.
Drought and nitrogen (N) deposition are major threats to global forests under climate change. However, investigation into how dioecious woody species acclimate to drought and N deposition and how ...this is influenced by gender has, so far, been unexplored. We examined the phenotypic and physiological changes in Salix myrtillacea females and males under 60 d drought, and wet N deposition on leaves’ treatments. Drought inhibited their growth by limiting water acquisition, photosynthesis, and increasing oxidative stress, especially in males. However, females exhibited greater drought resistance than males due to their better water acquisition ability and instantaneous water use efficiency (WUEsub.leaf), higher foliar abscisic acid (ABA) and auxin (IAA) levels and greater antioxidase activities. N deposition increased foliar ABA, Hsub.2Osub.2 accumulation, and reduced N distribution to the leaves, causing restricted photosynthesis and aerial growth in males. Interestingly, N deposition improved biomass accumulation in both the genders under drought, with greater positive effects on drought-stressed males by increasing their radial growth and causing greater N distribution to the leaves, increased foliar IAA and reduced oxidative stress. Regardless, S. myrtillacea females still showed better growth and drought resistance than males under both drought and N deposition. The females’ superior performance indicated that they are more appropriate for forestation, thus supporting the dominant gender’s selection in the afforestation of unisexual S. myrtillacea in drought and severe N deposition regions.
Flexible fiber-based supercapacitors (SCs) as power sources are highly anticipated for their potential applications in wearable and portable devices. However, it is still a big challenge to fabricate ...SCs with good electrochemical performance and high mechanical strength in a controllable and easy way. Here, we fabricated a reduced graphene oxide/Ti3C2T x /carbon nanotube (rGO/Ti3C2T x /CNT) fiber-based electrode using wet spinning and reduction processes. Benefiting from the π–π stacking interaction, hydrogen bonding and van der Waals’ forces between GO/Ti3C2T x hybrid nanosheets and treated CNTs, a wearable, flexible, and knittable rGO/Ti3C2T x /CNT-30 fiber electrode (272.0 MPa) was fabricated. More interestingly, the assembled symmetric all-solid SC from rGO/Ti3C2T x /CNT-30 exhibited a high volumetric capacitance (C v, 336.1 F·cm–3) and an excellent cycling stability after 3000 cycles at a current density of 2 A·cm–3. As a result, the fabricated SCs demonstrated a high volumetric energy density of 23.11 mWh·cm–3 at a power density of 1600 mW·cm–3 in the PVA/H2SO4 electrolyte. This work provides a designed rule for the fabrication of high-performance fiber-based SCs with potential applications in wearable, knittable, and portable devices.
Two-dimensional transition metal carbon/nitrides (MXenes) are promising candidates to revolutionize next-generation wearable sensors as high-performance surface-enhanced Raman scattering (SERS) ...substrates. However, low sensitivity of pure MXene nanosheets and weak binding force or uncontrolled in situ growth of plasmonic nanoparticles on hybrid MXene composites limit their progress toward universal and reliable sensors. Herein, we designed and manufactured a highly sensitive, structurally stable wearable SERS sensor by in situ fabrication of plasmonic nanostructures on the flexible TiVC membranes via the maximization of chemically reducing sites using alkaline treatment. DFT calculations and experimental characterization demonstrated that the hydroxyl functional groups on the surface of MXenes can facilitate the reduction of metal precursors and the nucleation of gold nanoparticles (AuNPs) and can be covalently attached to AuNPs. Thus, the fabricated flexible TiVC–OH-Au sensor satisfied the rigorous mechanical requirements for wearable sensors. In addition, combining the electromagnetic (EM) enhancement from dense AuNPs formed by the activation of nucleation sites and charge transfer (CT) between target molecule and substrate induced by the abundant DOS near the Fermi level of TiVC, the fabricated sensor exhibits ultrasensitivity, long-term stability, good signal repeatability, and excellent mechanical durability. Moreover, the proof-of-concept application of the wearable SERS sensor in sweat sensing was demonstrated to monitor the content of nicotine, methotrexate, nikethamide, and 6-acetylmorphine in sweat at the molecular level, which was an important step toward the universality and practicality of the wearable sensing technology.
The main contribution of semiconductor nanomaterials to surface-enhanced Raman scattering (SERS) comes from charge transfer (CT) between the absorbing molecules and the semiconductor. However, it is ...still challenging to realize the combined effects of the electromagnetic mechanism (EM) and the chemical mechanism (CM) for semiconductor-based SERS substrates. Herein, we demonstrate and design double-shelled ZnO (ZnO-DS) hollow microspheres by a modified hydrothermal/solvothermal process. SERS experiments and theoretical simulations proved that the excellent SERS activity is mainly attributed to the combined effect of Mie resonances generated by the nanocavities in the unique hollow double-shell nanoparticles and the CT effect excited by special structure ZnO. Particularly, the produced ZnO-DS SERS substrates exhibited a low limit of detection (LOD, 1 × 10–7 M for 4-MPY), outstanding sensitivity (EF = 1.2 × 104), and high stability (RSD = 10.4%, over 30 days of storage at room temperature). Furthermore, benefiting from the matching of energy levels of the ZnO-DS substrate and probe molecules, the sulfhydryl molecules with similar structures could be selectively distinguished in complex environments. We visualize that this work will resolve the current dilemma between sensitivity and selective detection of SERS substrates and expect to enable the monitoring of target molecules in the environment containing complex mixtures such as food safety and environmental protection.
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