Search

Dissociative chemisorption is the initial and often rate-limiting step in many heterogeneous processes. As a result, an in-depth understanding of the reaction dynamics of such processes is of great importance for the establishment of a predictive model of heterogeneous catalysis. Overwhelming experimental evidence has suggested that these processes have a non-statistical nature and excitations in various reactant modes have a significant impact on reactivity. A comprehensive characterization of the reaction dynamics requires a quantum mechanical treatment on a global potential energy surface. In this review, we summarize recent progress in constructing high-dimensional potential energy surfaces for polyatomic molecules interacting with transition metal surfaces based on the plane-wave density functional theory and in quantum dynamical studies of dissociative chemisorption on these potential energy surfaces. A special focus is placed on the mode specificity and bond selectivity in these gas–surface collisional processes, and their rationalization in terms of the recently proposed Sudden Vector Projection model. [ABSTRACT FROM AUTHOR]

For the construction of halide perovskite-based photoelectrochemical (PEC) biosensors in aqueous solution, the balance between retaining the excellent photoelectric performances of the halide perovskite and the protective modification of the halide perovskite has always been a challenging problem. In this work, a simple and sensitive photoelectrochemical biosensor based on inorganic halide perovskite CsPbBr3 as the photoactive material for the detection of alkaline phosphatase (ALP) was reported. The substrate sodium thiophosphate (Na3SPO3) can be catalyzed by ALP to produce hydrogen sulfide (H2S), which can react with the lead site on the surface of the CsPbBr3 film to form lead sulfide (PbS), resulting in a stable heterostructure and enhanced photocurrent intensity. The possible mechanism of enhanced photocurrent response of CsPbBr3/PbS heterojunctions was studied in detail. This work paves a new way for applying halide perovskites in different biosensor designs. [ABSTRACT FROM AUTHOR]

Cancer and neurological disorders are two leading causes of human death. Their early diagnoses will either greatly improve the survival rate or facilitate effective treatments or modalities. Detection of biomarkers in body fluids and some tissues (e.g., blood, urine and cerebrospinal fluids) is relatively non-invasive and provides useful chemical and biological information that is complementary to tomographic imaging (e.g., magnetic resonance imaging, positron emission tomography and X-ray computed tomography). Recent years have witnessed the contributions from and potential applications of bioanalytical methods for early detection of major diseases. In this review, we survey some recent developments of electroanalytical (as a representative label-based technique) and surface plasmon resonance (SPR) (as a representative label-free technique) biosensors for detection of biomarkers relevant to etiologies of breast cancer and Alzheimer's disease (AD). While breast cancer is representative of cancers of complexity (multiple biomarkers, false positives from tomographic scans, and a need for more effective early diagnostic methods), AD is the most prevalent neurological disorder that is also linked to multiple biomarkers. Both electroanalytical and SPR-based sensors have attractive features of sensitivity, portability, obviation of large sample volumes, and capability of multiplexed detection. Various sensing protocols developed in the past five years are reviewed, demonstrating the feasibility of both techniques for diagnostic purposes. Problems inherent in these two techniques that must be overcome before being clinically viable are also discussed. [ABSTRACT FROM AUTHOR]

A novel, highly stable, non-carbon support system for the oxygen reduction reaction (ORR) has been discovered in the form of nano-structured (NbxTi1−x)Ns (x = 0.25 and 0.5). Template-free, solid–solid separation synthetic approaches have been used for preparing these materials. The (NbxTi1−x)N materials have high specific surface area and better electronic conductivity than carbon-based supports. [ABSTRACT FROM AUTHOR]

Resistivity and powder X-ray diffraction measurements on Cs2Au2I6up to 320 kbar pressure show that the suppression of Au+/Au3+charge order above 55 kbar results in a non-metallic phase containing localised Au2+states that is irreversibly amorphised above 120 kbar, and a gradual metallisation observed above 175 kbar may result from decomposition within the amorphous material. [ABSTRACT FROM AUTHOR]

A simple and sensitive immunosensor for the detection of cancer biomarker prostate specific antigen (PSA) has been developed. Around the percolation threshold of the graphene film, the conductivity of the graphene film varies significantly with the surface adsorption of molecules, which can be used for the detection of proteins based on antibody–antigen binding. [ABSTRACT FROM AUTHOR]

Electrocatalytic high-throughput seawater electrolysis for hydrogen production is a promising green energy technology that offers possibilities for environmental and energy sustainability. However, large-scale application is limited by the complex composition of seawater, high concentration of Cl− leading to competing reaction, and severe corrosion of electrode materials. In recent years, extensive research has been conducted to address these challenges. Metal nitrides (MNs) with excellent chemical stability and catalytic properties have emerged as ideal electrocatalyst candidates. This review presents the electrode reactions and basic parameters of the seawater splitting process, and summarizes the types and selection principles of conductive substrates with critical analysis of the design principles for seawater electrocatalysts. The focus is on discussing the properties, synthesis, and design strategies of MN-based electrocatalysts. Finally, we provide an outlook for the future development of MNs in the high-throughput seawater electrolysis field and highlight key issues that require further research and optimization. [ABSTRACT FROM AUTHOR]

A silica ring-based ratiometric fluorescence nanosensing and imaging platform was established for the quantification of miRNA-21 with carbon dots and nucleic-functionalized gold nanoparticles inside and outside the ring, respectively. In the presence of miRNA-21, on one hand, the fluorescence emission signal of the originally quenched 6-carboxyfluorescein (FAM), which was labeled on the nucleic acid molecules that modified on the gold nanoparticles, was re-emitted. On the other hand, the fluorescence intensity of the carbon dots inside the ring remained essentially unchanged, which served to eliminate background interference. The ring rather than the shell well maintained the fluorescence of the carbon dots. The ratio of the recovered fluorescence intensity of FAM to the fluorescence intensity of the carbon dots was linearly correlated with the logarithm of miRNA-21 concentration. The linear range of the probe for miRNA detection was more than 3 orders of magnitude, and the detection limit was as low as 2.5 aM. The feasibility of the method for clinical application was verified by the quantitative analysis of intracellular miRNA. [ABSTRACT FROM AUTHOR]

Oxygen electroreduction (ORR) via a two-electron pathway is a promising alternative for hydrogen peroxide (H2O2) synthesis in small-scale applications. In this work, nitrogen and sulfur co-doped carbon coated zinc sulfide nanoparticles (ZnS@C) are synthesized using facile high-temperature annealing. In an alkaline electrolyte, the presence of ZnS suppresses the reduction of H2O2 during the ORR and contributes to high H2O2 selectivity (∼90%) over a wide potential range (0.40–0.80 V). Continuous generation of H2O2 is in turn achieved at an outstanding rate of 1.485 mol gcat.−1 h−1 with a faradaic efficiency of 93.7%. [ABSTRACT FROM AUTHOR]

The rational design of nanozymes as new "antibiotics" for bacterial therapy is a promising area in healthcare. Herein, B-doped core–shell Fe@BC nanozymes functioned with peroxidase-like activity for bacterial inhibition were studied. Experimental and theoretical results show that the BCO2 site enables a much lower energy barrier than the BC2O site, with a positive correlation between the density and activity of BCO2. The enzyme-like and positively-charged properties of core–shell Fe@BC improve the production and utilization of ˙OH to efficiently kill bacteria. This study not only highlights a promising peroxidase mimic for hygiene management but also deepens the understanding of B-doped carbon nanozymes. [ABSTRACT FROM AUTHOR]

In this paper, KIT-6 is used as a template to prepare ordered mesoporous materials WO3 and Au-loaded WO3 (Au–WO3). The pristine WO3 sensor and the Au–WO3 sensor are fabricated for the detection of 19 important gases, such as trimethylamine, formaldehyde and CS2. The results show that the Au–WO3 sensor has better selectivity and higher response to TMA. At a working temperature of 268 °C, the response (Ra/Rg) of the Au–WO3 sensor to 100 ppm of TMA is 41.56 and the response time is 1 s. In addition, the sensor has excellent response/recovery capabilities and stability. These high sensing performances are mainly attributed to the electronic and chemical sensitization of the noble metal Au and the presence of a high specific surface area supported by the mesoporous structure. Therefore, Au-doped mesoporous WO3 should be a promising material for a high performance TMA gas sensor. [ABSTRACT FROM AUTHOR]

To enable high-efficiency solar energy conversion, rational design and preparation of low cost and stable semiconductor photocatalysts with associated co-catalysts are desirable. However preparation of efficient catalytic systems remains a challenge. Here, N-doped TiO2/ternary nickel-zinc nitride (N–TiO2–Ni3ZnN) nanocomposites have been shown to be a multi-functional catalyst for photocatalytic reactions. The particle size of Ni3ZnN can be readily tuned using N–TiO2 nanospheres as the active support. Due to its high conductivity and Pt-like properties, Ni3ZnN promotes charge separation and transfer, as well as reaction kinetics. The material shows co-catalytic performance relevant for multiple reactions, demonstrating its multifunctionality. Density functional theory (DFT) based calculations confirm the intrinsic metallic properties of Ni3ZnN. N–TiO2–Ni3ZnN exhibits evidently improved photocatalytic performances as compared to N–TiO2 under visible light irradiation. [ABSTRACT FROM AUTHOR]

Fe-Doped NiO multi-shelled microspheres have been synthesized via a facile hydrothermal reaction. Various characterization techniques were introduced to investigate the structure and morphology of the as-prepared Fe-doped NiO multi-shelled microspheres. SEM and TEM observations showed that NiO microspheres are about 500 nm in diameter and with three shells. The Fe-doped NiO multi-shelled microspheres were investigated systematically as gas sensing materials for chemiresistive semiconductor-based gas sensors. The results showed that the 1.92 at% Fe-doped NiO (1.92Fe-NiO) multi-shelled microspheres exhibited enhanced gas sensing performance compared to the pure NiO multi-shelled microspheres. The gas response of 1.92Fe-NiO multi-shelled microspheres to 100 ppm butanol was 45.1 at 140 °C, which revealed a remarkable improvement over the pure NiO multi-shelled microspheres (6.80). The increased response of 1.92Fe-NiO multi-shelled microspheres may be attributed to the incorporation of Fe ions into NiO nanocrystals, which adjusted the carrier concentration and caused an increase in the oxygen species on the adsorbed surface. Therefore, the Fe-doped NiO multi-shelled microspheres should be a promising material for high performance butanol gas sensors. [ABSTRACT FROM AUTHOR]

A fast, sensitive, and convenient dual-emission water detector was robustly fabricated. This detector was prepared with blue fluorescent carbon dots (CDs) and red fluorescent Cu nanoclusters (NCs), and showed two well-resolved and intensity-comparable fluorescence peaks under a single excitation wavelength. Moreover, it showed strong red fluorescence in organic solvent due to the aggregation-induced emission enhancement (AIEE) properties of the Cu NCs, but the red fluorescence was gradually quenched with an increasing amount of water, whereas the blue fluorescence remained constant. The differences in response result in a continuous fluorescence color change from red to blue that can be clearly observed by the naked eye. Thus, as-prepared Cu NC-based dual-emission nanomaterials can be used for ratiometric fluorescence detection of trace amounts of water in organic solvents by taking advantage of the water sensitivity of their fluorescence intensity ratios (red/blue) and their low detect limits (＜0.02% v/v). These studies demonstrate that a novel and sensitive dual-emission ratiometric water detector has been found, which shows promise for application in environmental monitoring, food inspection, and life science. [ABSTRACT FROM AUTHOR]

One of the greatest challenges in the enhancement of the electrical properties of conductive mayenite [Ca24Al28O64]4+(4e−) (hereinafter C12A7:e−) is the design of a more suitable/simple synthesis strategy that can be employed to obtain the required properties such as excellent stable electrical conductivity, a high electron concentration, outstanding mobility, and an exceptionally large surface area. Therefore, to synthesize C12A7:e− in the metallic state, we proposed a facile, direct synthesis strategy based on an optimized sol–gel combustion method under a nitrogen gas environment using the low-cost precursors Ca(NO3)2·4H2O and Al(NO3)3·9H2O. Using this developed strategy, we successfully synthesized moderately conductive nanoscale C12A7:e− powder, but with unexpected carbon components (reduced graphene oxide (rGO) and/or graphene oxide (GO)). The synthesized C12A7:e− composite at room temperature has an electrical conductivity of about 21 S cm−1, a high electron concentration of approximately 1.5 × 1021 cm−3, and a maximum specific surface area of 265 m2 g−1. Probably, the synthesized rGO was coated on nanocage C12A7:e− particles. In general, the C12A7:e− electride is sensitive to the environment (especially to oxygen and moisture) and protected by an rGO coating on C12A7:e− particles, which also enhances the mobility and keeps the conductivity of C12A7:e− electride stable over a long period. Doped mayenite electride exhibits a conductivity that is strongly dependent on the substitution level. The conductivity of gallium-doped mayenite electride increases with the doping level and has a maximum value of 270 S cm−1, which for the first time has been reported for the stable C12A7:e− electride. In the case of Si-substituted calcium aluminate, the conductivity has a maximum value of 222 S cm−1 at room temperature. [ABSTRACT FROM AUTHOR]

Proteins were proved to be type-independent templates for the biomineralization of iron ions into hematite mesocrystals with tunable structures and morphologies under hydrothemal conditions. Our finding could pave the way for the synthesis of mesocrystals with controlled stuctures and morphologies using templates of low-cost proteins. [ABSTRACT FROM AUTHOR]