Latest ArticlesPlants play a crucial role in maintaining ecological balance and biodiversity. However, plant health is easily affected by environmental stresses. Hence, the rapid and precise monitoring of plant health is crucial for global food security and ecological balance. Currently, traditional detection strategies for monitoring plant health mainly rely on expensive equipment and complex operational procedures, which limit their widespread application. Fortunately, near-infrared (NIR) fluorescence and surface-enhanced Raman scattering (SERS) techniques have been recently highlighted in plants. NIR fluorescence imaging holds the advantages of being non-invasive, high-resolution and real-time, which is suitable for rapid screening in large-scale scenarios. While SERS enables highly sensitive and specific detection of trace chemical substances within plant tissues. Therefore, the complementarity of NIR fluorescence and SERS modalities can provide more comprehensive and accurate information for plant disease diagnosis and growth status monitoring. This article summarizes these two modalities in plant applications, and discusses the advantages of multimodal NIR fluorescence/SERS for a better understanding of a plant's response to stress, thereby improving the accuracy and sensitivity of detection.
Engineering of sulfur vacancies on the basal plane of molybdenum disulfide (MoS2) may provide effective way to promote the catalytic activity. Although the sulfur vacancy density has previously been correlated with catalytic activity, direct evidence that vacancies create surfaces with enhanced electrocatalytic activity is still lacking. Here, we used a combination of scanning electrochemical cell microscopy (SECCM) with submicrometer resolution and photoluminescence imaging to show that sulfur vacancies in monolayer MoS2 microflakes lead to significant spatial heterogeneity in the electrochemical hydrogen evolution reaction (HER) activity. Specifically, colocated multi-microscopy unveils that regions with superior HER activity are associated with sulfur vacancy defects. As the vacancy density increases, the triangular flakes display significantly enhanced and spatially uniformly distributed electrocatalytic activity. Our multi-microscopic imaging approach using SECCM convincingly highlights the spatial heterogeneity of electrocatalytic activity across monolayer MoS2 by sulfur vacancy engineering.
Surface-confined metal-organic frameworks have emerged as versatile structures with a broad spectrum of applications such as nanoelectronics, catalysis, sensing, and molecular storage, owing to their unique structural and electronic properties. However, the exploration and optimization of molecular networks typically involve resource-intensive trial-and-error experiments. The complexity comes from factors like metal nodes, organic ligands, substrates, and the preparation conditions. To address this challenge, high-throughput methodologies have been used in materials exploration. In this work, we explored a high-throughput method for preparing sub-monolayer metals with continuous coverage spread on metal surfaces. By employing a physical mask during metal deposition under ultra-high vacuum conditions, we achieved sample libraries with copper (Cu) and silver (Ag) adatoms on the metal substrates, and constructed surface-supported metal-organic frameworks with varying metal-to-molecule stoichiometric ratios. This approach facilitates the exploration of surface-confined metal-organic frameworks, particularly in terms of varying metal-to-ligand stoichiometric ratios, offering an efficient pathway to unlock the potential of these intricate two-dimensional networks.
Utilizing superwettability micro/nanostructures to enhance the condensation heat transfer (CHT) performance of engineering materials has attracted great interest due to its values in basic research and technological innovations. Currently, exploring facile micro/nanofabrication approaches to create high-efficiency CHT surfaces has been one of research hotspots. In this work, we propose and demonstrate a type of new superwettability hybrid surface for high-efficiency CHT, which consists of superhydrophobic nanoneedle arrays and triangularly-patterned superhydrophilic microdots (SMDs). Such hybrid surface can be fabricated by the facile growth of densely-packed ZnO nanoneedles on the Zn-electroplated copper surface followed by fluorosilane modification and mask-assisted photodegradation. Through regulating the diameters and interspaces of SMDs, we obtain the optimized triangularly-patterned hybrid surface, which shows 42.7% higher CHT coefficient than the squarely-patterned hybrid surface and 58.5% higher CHT coefficient than the superhydrophobic surface. The key of such hybrid surface design is to considerably increase CHT coefficient brought about by SMD-triggered drop sweeping at the cost of slightly reducing heat transfer area of superhydrophobic functional zone for drop jumping. Such new strategy helps develop advanced CHT surfaces for high-efficiency electronic cooling and energy utilization.
The development of stable and efficient non-noble metal cocatalysts has arisen as a promising yet challenging endeavor in the context of photocatalytic overall water splitting. In this study, NiCo alloy cocatalysts were synthesized with nickel/cobalt metal organic framework (NiCo-MOF) as source of nickel and cobalt. Systematic characterization results demonstrate the successful deposition of alloy cocatalysts onto the surface of SrTiO3. The prepared SrTiO3 loaded NiCo-alloy can generate hydrogen and oxygen in a stoichiometric ratio for photocatalytic overall water splitting, achieving an apparent quantum yield of 11.9% at 350 ± 10 nm. Theoretical calculations indicate that the introduction of cobalt has a beneficial regulatory effect on the hydrogen evolution sites of Ni, reducing the free energy of H adsorption. The synergistic catalytic effect of bimetallic catalysts contributes to enhancing photocatalytic activity and stability. This study offers constructive insights for the development of high-efficiency and cost-effective cocatalyst systems.
The tert-butyl nitrite as a bifunctional reagent mediated radical alkene difunctionalization has emerged as a powerful strategy for synthesis of structurally diverse oxime-containing compounds. However, the phosphorus-centered radical initiated transformations remain largely elusive. Herein, a visible-light-induced radical phosphinoyloximation of alkenes with secondary phosphine oxides and tert-butyl nitrite has been developed under photocatalyst- and metal-free conditions. This protocol features mild conditions, broad substrate scope, good functional tolerance, and operational simplicity, yielding a diverse array of α-phosphinoyl oximes in moderate to good yields with high stereoselectivities. The photomediated homolytic cleavage of ONO bond of tert-butyl nitrite generates the reactive tert-butoxyl radical and persistent NO radical to act as both HAT reagent and the source of oximes.
As one of the most essential components in photocuring system, photoinitiators (PIs) exert a crucial influence on the properties of the cured product. However, commercially available PIs encounter challenges in simultaneously achieving efficient photoinitiation performance and excellent light absorption properties, significantly limiting their applications in various fields. Here, two bis-chalcones and four corresponding oxime esters (OXEs) were designed and synthesized as highly efficient PIs. Featuring a structure comprising bis-chalcone and two diphenyl sulfides, the conjugated systems in these compounds enhance their light-absorption properties in near-ultraviolet and visible region, effectively. Both the frontier molecular orbital simulations and excited state calculations suggest the contribution of sulfur atoms to electron delocalization and the formation of conjugated structure. Due to the high reactivity of the NO bond in OXE moiety, the four OXEs exhibit exceptional free radical photoinitiating ability in commercial acrylic monomers/oligomers with LED@365 nm as light source. Notably, one of them demonstrates superior performance in the photoinitiation of multifunctional crosslinker, achieving more than 70% conversion within 3 s, coupled with outstanding absorption at 365 nm. These chalcone-based OXEs are considered to exert significant potential in the realm of free radical photocuring.
Developing high performance electrocatalysts for the cathodic oxygen reduction reaction (ORR) is essential for the widespread application of fuel cells. Herein, a promising Pt2NiCo atomic ordered ternary intermetallic compound with N-doped carbon layer coating (o-Pt2NiCo@NC) has been synthesized via a facile method and applied in acidic ORR. The confinement effect provided by the carbon layer not only inhibits the agglomeration and sintering of intermetallic nanoparticles during high temperature process but also provides adequate protection for the nanoparticles, mitigating the aggregation, detachment and poisoning of nanoparticles during the electrochemical process. As a result, the o-Pt2NiCo@NC demonstrates a mass activity (MA) and specific activity (SA) of 0.65 A/mgPt and 1.41 mA/cmPt2 in 0.1 mol/L HClO4, respectively. In addition, after 30,000 potential cycles from 0.6 V to 1.0 V, the MA of o-Pt2NiCo@NC shows much lower decrease than the disordered Pt2NiCo alloy and Pt/C. Even cycling at high potential cycles of 1.5 V for 10,000 cycles, the MA still retains ~70%, demonstrating superior long-term durability. Furthermore, the o-Pt2NiCo@NC also exhibits strong tolerance to CO, SOx, and POx molecules in toxicity tolerance tests. The strategy in this work provides a novel insight for the development of ORR catalysts with high catalytic activity, durability and toxicity tolerance.
Efficient and innovative nano-catalytic oxidation technologies offer a breakthrough in removing emerging contaminants (ECs) from water, surpassing the limitations of traditional methods. Environmental functional materials (EFMs), particularly high-end oxidation systems using eco-friendly nanomaterials, show promise for absorbing and degrading ECs. This literature review presents a comprehensive analysis of diverse traditional restoration techniques-biological, physical, and chemical-assessing their respective applications and limitations in pesticide-contaminated water purification. Through meticulous comparison, we unequivocally advocate for the imperative integration of environmentally benign nanomaterials, notably titanium-based variants, in forthcoming methodologies. Our in-depth exploration scrutinizes the catalytic efficacy, underlying mechanisms, and adaptability of pioneering titanium-based nanomaterials across a spectrum of environmental contexts. Additionally, strategic recommendations are furnished to surmount challenges and propel the frontiers of implementing eco-friendly nanomaterials in practical water treatment scenarios.
Achieving seamless tiling through the self-assembly of organic species has long fascinated scientists for its potential applications across various fields. However, constructing periodic nanostructures with high-order tessellation remains challenging, particularly in achieving precise control at the supramolecular level. In this study, we present the successful creation of multiple seamless 2D tessellations on Au (111) surface using versatile hexagonal tiles derived from a singular molecular unit, namely 2,6,10-tribromotricycloquinazoline. Through scanning tunneling microscopy imaging, seven distinct 2D tessellations, ranging from regular to semiregular to k-uniform tilings, are unveiled at the molecular level. Density functional theory calculations provide a theoretical basis for the formation of these complex 2D tessellation, highlighting the important role of the variability of Br···Br/H contacts in facilitating complex seamless 2D tessellations on surface. This work opens avenues for exploring possibilities in constructing intricate tiling patterns with diverse applications.
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