The development of efficient and reversible ammonia (NH3) adsorbents is crucial for advancing ammonia fuel cell technology. Key challenges in the ammonia adsorption-desorption process include achieving high uptake/release efficiency, favorable kinetics, and stable cycling lifetime. Herein, we report a strategy to prepare high-performance ammonia adsorbents by partially etching metal-organic frameworks (MOFs) with tannic acid (TA). Partial etching by protonated TA not only exposes metal active sites but also chelates metal ions, significantly enhancing both the adsorption capacity and the stability during adsorption-desorption cycles. This strategy retains the high specific surface area of the micropores and the chelating functional groups while alleviating premature pore blockage caused by capillary condensation of ammonia on the material surface, thereby improving adsorption kinetics. The partially etched ZIF-67 achieves a reversible capacity as high as 58 mmol g-1 at 298 K and 7 bar, theoretically corresponding to a hydrogen content of 7.5%. The generated hierarchical pore network facilitates ammonia desorption, reducing the temperature and energy required for regeneration, with complete desorption achieved at 364 K. Moreover, the partially etched MOF exhibits excellent ammonia adsorption selectivity, offering a new approach for the purification of industrial exhaust gases. In situ infrared spectroscopy and theoretical calculations reveal that the enhanced adsorption arises from weak chemisorption, benefiting from an increased density of adsorption sites within the engineered pore environment. This strategy provides a new avenue for designing integrated, efficient, and safe systems for ammonia fuel storage and release.

The trace-level monitoring of organophosphate pesticides (OPs, e.g., phoxim) is crucial for food safety, yet it remains severely hindered by the intrinsic sluggish kinetics properties of OPs and the single-functionality of traditional sensing interfaces, leading to poor sensitivity and low anti-interference capability. Within this context, a novel interface engineering strategy centered on nanozymes is proposed in this study. This approach employs intrinsic enzyme-like catalytic activity to enhance optical signal amplification, while multi-dimensional structural networks ensure efficient charge transfer, enabling highly sensitive electrochemical sensing capabilities at the interface. Specifically, based on “defect-induced, metal-anchored” interface engineering synthesis strategy, heterogeneous structure was constructed by in situ growing nitrogen-rich COFs on carbon nanotubes (CNT). Subsequently, NiCo bimetal was precisely anchored at the defect interfaces via pyrolysis, effectively preparing the NiCo-SNW-1@CNT nanozyme with excellent catalytic performance. A dual-mode sensing platform for organophosphorus pesticides, which integrates colorimetric and electrochemical detection capabilities, has been developed by taking advantage of the significantly enhanced peroxidase-like activity and accelerated electron transfer properties of this tailored interface. The synergistic output enables dual-signal cross validation, effectively reducing matrix interference for reliable detection of organophosphorus analytes. The designed interface of NiCo-SNW-1@CNT enables dual-mode phoxim detection: competitively suppressing ROS to induce color fading colorimetrically and facilitating a direct electrochemical response via efficient electron transport. Overall, the design of dual-signal platform has successfully overcome the instability limitations of natural enzymes (AChE), and the proposed heterogeneous interface engineering strategy offers promising approach for the rapid and convenient detection of organophosphate pesticides in vegetable and water samples.

Selenium is an essential trace element for the human body, renowned for its antioxidant properties, immune system enhancement, and potential in cancer prevention. Hubei Province possesses abundant selenium resources in its soil. Enshi Prefecture hosts the world's only independent selenium deposit, while the Jianghan Plain boasts superior quality and contiguous distribution of selenium-rich soil. This combined advantage provides a solid resource foundation for developing the selenium-rich industry in Hubei Province. However, due to factors such as soil pH, organic matter content, and redox potential, the bioavailability of selenium in the soil is low, making it difficult for crops to absorb efficiently, which constrains the development of the selenium-rich industry. This study systematically investigated technical methods for enhancing soil selenium availability through laboratory simulation experiments and field trials. Furthermore, by integrating the characteristics of selenium content and distribution in Hubei's soils, it delved into the mechanisms of different activation techniques. The research aims to provide scientific evidence and technical support for the efficient development and utilization of selenium-rich soil resources in Hubei Province.

Ammonia is an alternative hydrogen storage material and a promising source of sustainable clean energy. The lack of a mechanistic understanding of ammonia electrooxidation hinders the efforts to overcome the slow kinetics of the anode reaction in direct ammonia fuel cells. Herein, we use surface-enhanced Raman spectroscopy to study the electro-decomposition of ammonia on the Au surface. We observe three key reaction intermediate species of *NH2, *NH and *NNH and thereby disclose a multistage interfacial decomposition mechanism. Among the three, detection of the N-coupled species fills the blank in the mechanistic study of ammonia oxidation. Additionally, we investigated the influence of the reactant concentrations on the different oxidation stages. This spectroscopic evidence opens up promising avenues to overcome the limitations associated with ammonia fuel cells.

Electrochemical-nitrate-reduction-reaction (eNitRR) synthesis of ammonia is an effective way to treat nitrate wastewater and alleviate the pressure of the Haber-Bosch ammonia production industry. How to develop effective catalysts to electrochemically reduce nitrate to ammonia and purify sewage under complex environmental conditions is the focus of current research. Herein, the dopamine polymerization process and the [(C₁₂H₈N₂)2Cu]2+ complex embedding process were run simultaneously in time and space, and ultrafine Cu nanoparticles (Cu/CN) were effectively loaded on nitrogen-doped carbon after heat treatment. Using Cu/CN as the catalyst, the ammonia yield rate and Faradaic efficiency of the electrochemical conversion of NO3− to NH3 are highly 8984.0 μg h−1 mgcat.−1 and 95.6%, respectively. Even in the face of complex water environments, such as neutral media, acidic media, coexisting ions, and actual nitrate wastewater, nitrate wastewater can be effectively purified to form high value-added ammonia. The strategy of simultaneous embedding increases the exposure rate of Cu sites, and the support of CN is also beneficial to reduce the energy barrier of *NO3 activation. This study rationally designed catalysts that are beneficial to eNitRR, and considered the situation faced by practical applications during the research stage, reducing the performance gap between laboratory exploration and industrial applications.

Flexible Zn–air batteries (FZABs) exhibit low cost and inherent safety and have potential for application in wearable electronic devices. Nevertheless, balancing the high energy density and flexibility of the self-supported electrodes in FZABs is still a challenge. Herein, we develop a novel superassembly strategy for the preparation of N, S-codoped porous carbon frameworks (NS@CFs) as cathodes in FZABs. Benefiting from the abundant heteroatom defect sites, NS@CF exhibits excellent electrocatalytic performance for the oxygen reduction reaction (ORR), including high electrochemical activity and long-term stability. When used as the cathode in a liquid flowing ZAB, NS@CF exhibited a power density of 221 mW cm −2 and achieved a 60% improvement over Pt/C-based ZABs. This new ZAB exhibited a high specific capacity of 792 mA h g Zn −1 , excellent long-term durability and cycling stability, which is superior to those of ZABs assembled with commercial Pt/C cathodes. In addition, the flexible NS@CF with directional channels can be used as independent air cathodes for FZABs, where it provides small charge/discharge voltage gaps, a power density of 49 mW cm −2 and outstanding cycling stability. This work provides a novel strategy for designing and fabricating highly efficient integrated electrodes for flexible and wearable electrochemical devices.

Flexible Zn-air batteries (FZABs), with low cost and inherent safety, have potential applications in wearable electronic devices. Nevertheless, balancing high energy density and flexible self-supporting of electrodes is still a challenge. Herein, we develop a novel method of directed freezing and pyrolysis for the preparation of N, S co-doped porous carbon aerogel (NS@CA) as cathodes in FZABs. The obtained NS@CA exhibits excellent oxygen reduction reaction (ORR) electrocatalytic properties, including high electrochemical activity and long-time stability. When used as a cathode in the liquid flowing ZABs, NS@CA possesses a power density of 221 mW cm -2 , a 60% improvement over Pt/C-based ZABs. This new ZAB exhibits high specific capacity of 792 mAh g Zn -1 , and excellent long-term durability and cycling stability, which is superior to ZABs assembled with commercial Pt/C cathodes. In addition, the flexible NS@CA with directional channels can be used as an independent air cathode for FZABs, providing a smaller charge/discharge voltage gap and a power density of 49 mW cm -2 together with outstanding cycling stability. This work provides a new strategy to design and fabricate highly efficient integrated electrodes for flexible and wearable electrochemical devices.

Mesoporous silica nanoparticles (MSNs) functionalized with benzimidazole-derived fluorescent molecules (DHBM) are fabricated via a feasible interfacial superassembly strategy for the highly sensitive and selective detection of Cu2+. DHBM-MSN exhibits an obvious quenching effect on Cu2+ in aqueous solutions, and the detection limit can be as low as 7.69x10(-8) M. The DHBM-MSN solid-state sensor has good recyclability, and the silica framework can simultaneously improve the photostability of DHBM. Two mesoporous silica nanoparticles with different morphologies were specially designed to verify that nanocarriers with different morphologies do not affect the specific detectionability. The detection mechanism of the fluorescent probe was systematically elucidated by combining experimental results and density function theory calculations. Moreover, the detection system was successfully applied to detect Cu2+ in bovine serum, juice, and live cells. These results indicate that the DHBM-MSN fluorescent sensor holds great potential in practical and biomedical applications.

Capacitive deionization (CDI), known as an emerging, environment-friendly, energy-efficient and cost-effective technology, has gained tremendous attention and shown great application potential in brackish water desalination. However, the limited electrical double layer (EDL) capacitance and desalination capacity of conventional carbon-based electrodes seriously affect its practical application. Here, we prepared a flexible, self-supporting, zinc oxide-modified N-doped porous carbon nanofiber membrane (ZnO@N-PCNM) as capacitive deionized electrode materials. The prepared carbon membrane possesses a large specific surface area (488.6 m2 g-1) due to the interconnected and hierarchical multi-layer pores, which can provide more adsorption sites and good electronic/ion conductivity. In addition, benefiting from the high N-doping (10.9%) and the loading of Zn, the prepared ZnO@N-PCNM electrode shows a specific capacitance of 253.62 F g-1 in 3 M KOH electrolyte at a scanning rate of 5 mV s-1. As electrode materials for CDI, the ZnO@N-PCNM delivers an outstanding electrosorption capacities of 32.87 mg g-1, 23.81 mg g-1 and 20.85 mg g-1 at a low pressure of 1.8 V for heavy metal ions Pb2+, Cu2+, and Cd2+, respectively. These results mean that the prepared ZnO@N-PCNM membrane has great potential for Hybrid capacitive deionization practical applications.

Transition metal sulfides have emerged as promising materials in supercapacitor. In this work, we firstly developed an interface-induced superassembly approach to fabricate NiSx and CoSx nanoparticles, which based on ordered mesoporous carbon-graphene aerogel composites for supercapacitor electrodes. The obtained multi-component superassembled nanoparticles-carbon matrix composites have controllable 3D porous structure of multi-stage composite. The two-dimensional graphene interlaced to form a 3D framework with large sponge-like pores, and then the graphene surface was loaded with mesoporous carbon with mesoporous pore size and vertical orientation. The composites display high specific capacitance of 958.1 F g(-1) at 0.1 A g(-1). The capacitance retains about 97.3 % after 3000 charging-discharging cycles at 2 A g(-1). These results indicate that the obtained OMC-GA-Ni3S2/Co4S3 is a promising material for electrochemical capacitors, which providing new technical methods and ideas for the research of new energy and analytical sensor materials in the fields of energy storage, photocatalysis, point-of-care testing devices and other fields.

A novel approach is developed to fabricate an ultra-thin layered flexible wearable Surface-Enhanced Raman Scattering (SERS) substrate named silk fibroin-anodic aluminum oxide-Au nanoparticles (SF-AAO-Au), which consists of biocompatible SF film as flexible support, ultrathin cavity AAO as template, and plasmonic Au NPs. The SF-AAO-Au sensor exhibits excellent SERS mechanical flexibility, homogeneity and sensitivity for its effective enhancement ability and highly ordered 3D periodic porous particle-in-cavity (PIC) arrays structure. The humidity-driven interface structure of biocompatible SF film provides good skin adhesion under various fitness tests and excellent mechanical flexibility as a wearable SERS sensor on natural skin (deformation within 5%). The flexible SF-AAO-Au can be developed as quantitative sweat glucose sensor in the concentration range of 10(-7) to 10(-3) M with a limit of detection (LOD) of 1.68 x 10(-7) M and qualitative human sweat glucose detection ability. This SF-AAO-Au substrate can be further designed as lab-on-glove SERS sensing platform for ultrasensitive (LOD similar to 5.7 ppt) quantitative on-site detection of agricultural residues in a wide range. The effective dual functional SERS wearable sensor realized for the first time paves a new way to develop smart wearable and nondestructive devices in environmental safety, forensic identification and point-of-care testing (POCT) diagnosis of physiological disease.

Rapid, simple, and reliable detection of toxics at trace level is of great significance for public health. Surface-enhanced Raman spectroscopy (SERS) as a powerful vibrational spectroscopic technique for molecules probing provides great advantages in trace detection; however, the low reproducibility of SERS signals from spot to spot and substrate to substrate remains a great challenge restricting its real applications. Here, we report a facile method for reproducibly preparing highly uniform self-assembled monolayers of gold nanostars (Au NSs SAM) as SERS substrates using the classic Langmuir-Blodgett technique and introduced a statistical method to explore the signal reproducibility by t test. Our results show that the Au NSs SAM substrates fabricated in the same batch and different batches generated constant SERS signals without statistical differences and could detect dye molecules CV, R6G, and RhB in solution at concentrations as low as 10(-8), 10(-8), and 10(-7) M, respectively. We then applied the Au NSs SAM for trace detection of Tetracycline (TC), one of the most widespread antibiotics entering the food chain and threatening the ecological balance. A detection limit of 0.05 mu g/ml was achieved, with a linear response between SERS signal and TC concentration in the range of 0.05-10 mu g/ml. Overall, this uniform Au NSs SAM could be reproducibly fabricated to provide a reliable platform for trace detection of TC residues or other toxics in water and is expected to have broad applications in different fields including environmental monitoring, food security, and so on.

Traditional single sensor is designed based on the "lock-and-key" mode, which only relies on the most dominant interactions between the sensing element and the target. Although it exhibits high selectivity, there are challenges in detecting multiple analytes at the same time. Here, a sensor array with three sensing elements is developed to detect multiple heavy metal ions simultaneously and quickly. In our experiment, bovine serum albumin-encapsulated gold nanoclusters (BSA-AuNCs) were used as fluorescence probes and three different dopamine (DA) concentrations as nonspecific receptors. As we know, self-polymerized polydopamine (PDA) can quench part of the fluorescence of BSA-AuNCs. Upon the addition of the heavy metal ions, the diverse non-specific interactions between DA and heavy metal ions result in the difference in the number of the remaining PDA. Therefore it would lead to different degrees of fluorescence recovery behavior. This unique "turn-on" fluorescence response mode can be analyzed by linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA). Two-dimensional, three-dimensional and even four-dimensional mixed ions detection and quantitative detection have also been achieved. Moreover, by using this fluorescence array mode, heavy metal ions in tap water or blood samples can be detected.

Monolayer 2H-MoS2 has been widely noticed as a typical transition metal dichalcogenides (TMDC) for surface-enhanced Raman scattering (SERS). However, monolayer MoS2 is limited to a narrow range of applications due to poor detection sensitivity caused by the combination of a lower density of states (DOS) near the Fermi energy level as well as a rich fluorescence background. Here, surfaced S and Mo atomic defects are fabricated on a monolayer MoS2 with a perfect lattice. Defects exhibit metallic properties. The presence of defects enhances the interaction between MoS2 and the detection molecule, and it increases the probability of photoinduced charge transfer (PICT), resulting in a significant improvement of Raman enhancement. Defect-containing monolayer MoS2 enables the fluorescence signal of many dyes to be effectively burst, making the SERS spectrum clearer and making the limits of detection (LODs) below 10−8 M. In conclusion, metallic defect-containing monolayer MoS2 becomes a promising and versatile substrate capable of detecting a wide range of dye molecules due to its abundant DOS and effective PICT resonance. In addition, the synergistic effect of surface defects and of the MoS2 main body presents a new perspective for plasma-free SERS based on the chemical mechanism (CM), which provides promising theoretical support for other TMDC studies.

Acetamiprid poses a serious threat to human beings. In this work, the highly transparent fluorescent quantitative PCR sealing membranes (PCR-M) developed in our previous work which had attractive characteristics such as sensitivity, stability and reproducibility, and its capability of extracting analytes quickly, was used to detect acetamiprid. The detection limit of 1 nmol/L was obtained by direct detection of CN group in acetamiprid. In order to improve the selectivity and sensitivity, acetamiprid aptamer was introduced. After the interaction of aptamer with acetamiprid the SERS signal of adenine at 730 cm(-1) increased. The detection limit of indirect detection was 10(-8) mol/L. Aptamer advanced Ag-PCR-M-based Surface enhanced Raman spectroscopy (SERS) method for indirect SERS detection which significantly improves the detection sensitivity and greatly increases the range of signal response value. This will be conducive to the detection of actual samples and expand the practical application. (C) 2021 Elsevier B.V. All rights reserved.

The central dilemma in label-free in situ surface-enhanced Raman scattering (SERS) for monitoring of heterogeneously catalyzed reactions is the need of plasmonically active nanostructures for signal enhancement. Here, we show that the assembly of catalytically active transition-metal nanoparticles into dimers boosts their intrinsically insufficient plasmonic activity at the monomer level by several orders of magnitude, thereby enabling the in situ SERS monitoring of various important heterogeneously catalyzed reactions at the single-dimer level. Specifically, we demonstrate that Pd nanocubes (NCs), which alone are not sufficiently plasmonically active as monomers, can act as a monometallic yet bifunctional platform with both catalytic and satisfactory plasmonic activity via controlled assembly into single dimers with an ∼1 nm gap. Computer simulations reveal that the highest enhancement factors (EFs) occur at the corners of the gap, which has important implications for the SERS-based detection of catalytic conversions: it is sufficient for molecules to come in contact with the "hot spot corners", and it is not required that they diffuse deeply into the gap. For the widely employed Pd-catalyzed Suzuki-Miyaura cross-coupling reaction, we demonstrate that such Pd NC dimers can be employed for in situ kinetic SERS monitoring, using a whole series of aryl halides as educts. Our generic approach based on the controlled assembly into dimers can easily be extended to other transition-metal nanostructures.

Rapid and effective detection of pesticide residues from complex surfaces of fruits and vegetables has important significance. Herein, we report a novel three-dimensional (3D) hierarchical porous functional surface-enhanced Raman scattering (SERS) substrate, which is fabricated by successive two-step hydrothermal synthesis strategy of silver nanoparticles (Ag NPs) and cobalt oxide nanowires (Co3O4 NWs) on the 3D copper foam framework as Cu@Co3O4@Ag-H. The strategy offers a new avenue for localized plasmonic materials distribution and construction, which exhibits better morphology regulation ability and SERS activity (or hotspots engineering) than physical spurring obtained Cu@Co3O4@Ag-S. The developed Cu@Co3O4@Ag-H possesses large surface area and rich hotspots, which contributes to the excellent SERS performance, including homogeneity (RSD of 7.8%), sensitivity (enhancement factor, EF of 2.24 × 108) and stability. The Cu@Co3O4@Ag-H not only provides plenty of Electromagnetic enhancement (EM) hotspots but also the trace detection capability for droplet rapid sensing within 2 s. Cu@Co3O4@Ag-H substrate is further developed as an effective SERS sensing platform for pesticide residues detection on the surfaces of fruits and vegetables with excellent LOD of 0.1 ppm, which is lower than the most similar reported works. This work offers new potential for bioassay, disease POCT diagnosis, national security, wearable flexible devices, energy storage and other related fields.

Recent years, two-dimensional transition metal carbonitrides, MXene, have emerged as SERS substrates due to their unique optical and electrical properties. In order to combine the advantages of metal nanoparticles and MXene for SERS substrates, this paper prepared an MXene (Ti3C2Tx)-Ag nanoparticles (NPs) hybrid biosensor through in-situ electrostatic self-assembly method, in which the citrate-coated Ag NPs are loaded on the negatively surface of Ti3C2Tx flakes through positively charged PDDA polymer. The characterizations show that a large number of Ag NPs uniformly adsorb on both side of Ti3C2Tx nanosheets. The prepared platform exhibits excellent SERS performance, long-term stability and good uniformity by detecting 4-MBA molecules. The electromagnetic field distribution was simulated to theoretically show the Raman enhancement mechanism of this platform. In order to explore the possible application of the sensor in clinical diagnosis and monitoring of biological environment, the platform was used for biomolecule detection. The detection limit of adenine molecules can be as low as 10(-8) M. For dopamine molecules with concentration ranging from 5 x 10(-6) M to 5 x 10(-8) M, the SERS results show a linear relationship between peak intensity and concentration of dopamine molecules. The biosensor was applied for serum detection. The results suggest that MXene-PDDA-Ag NPs hybrid platform could be used as a sensitive and uniform biosensor for label-free quantitative detection of bio-molecular based on SERS method, which could be applied in the field of biotechnology.

Air and water pollution poses a serious threat to public health and the ecological environment worldwide. Particulate matter (PM) is the major air pollutant, and its primary sources are processes that require high temperatures, such as fossil fuel combustion and vehicle exhaust. PM0.3 can penetrate and seriously harm the bronchi of the lungs, but it is difficult to remove PM0.3 due to its small size. Therefore, PM0.3 air filters that are highly efficient and resistant to high temperatures must be developed. Polyimide (PI) is an excellent polymer with a high temperature resistance and a good mechanical property. Air filters made from PI nanofibers have a high PM removal efficiency and a low air flow resistance. Herein, zeolitic imidazolate framework-8 (ZIF-8) was used to modify PI nanofibers to fabricate air filters with a high specific surface area and filtration efficiency. Compared with traditional PI membranes, the ZIF-8/PI multifunction nanofiber membranes achieved super-high filtration efficiency for ultrafine particles (PM0.3, 100%), and the pressure drop was only 63 Pa. The filtration mechanism of performance improvement caused by the introduction of ZIF-8/PI nanofiber membrane is explored. Moreover, the ZIF-8/PI nanofiber membranes exhibited excellent thermal stability (300 C) and efficient water–oil separation ability (99.85%).

Structural investigations, based on density functional theory (DFT) calculations, are performed on tea catechins, including 4-aminobutyric acid (GABA), L-theanine (Thea), caffeine (CAF), theobromine (TB), theophylline (TP), catechin (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), catechin gallate (CG), epicatechin gallate (ECG), gallocatechin gallate (GCG) and epigallocatechin gallate (EGCG). With an identified lowest energy conformer of investigated molecules, FTIR and FT-Raman spectra have been assigned according to DFT calculations in the way of B3LYP/6-31 + G (d, p). Normal spectra of these catechin powders are also measured by Raman spectrometers. There is a kind of everlasting correlation between experimental results and theoretical data. And our research has also obtained a clear evidence for reliable assignments of vibrational bands, bringing great feasibility to the rapid tea catechin detection.