The electrochemical nitrogen reduction reaction (NRR) as an energy-efficient approach for ammonia synthesis is hampered by the low ammonia yield and ambiguous reaction mechanism. Herein, phosphorus-doped carbon nanotube (P-CNTs) is developed as an efficient metal-free electrocatalyst for NRR with a remarkable NH3 yield of 24.4 μg·h−1·mg−1cat. and partial current density of 0.61 mA·cm−2. Such superior activity is found to be from P doping and highly conjugated CNTs substrate. Experimental and theoretical investigations discover that the electron-deficient phosphorus sites with Lewis acidity should be genuine active sites and NRR on P-CNTs follows the distal pathway. These findings provide insightful understanding on NRR processes on P-CNTs, opening up opportunities for the rational design of highly-active cost-effective metal-free catalysts for electrochemical ammonia synthesis.
相似文献Electrochemical N2 reduction offers a promising alternative to the Haber-Bosch process for sustainable NH3 synthesis at ambient conditions, but it needs efficient catalysts for the N2 reduction reaction (NRR). Here, we report that FeOOH quantum dots decorated graphene sheet acts as a superior catalyst toward enhanced electrocatalytic N2 reduction to NH3 under ambient conditions. In 0.1 M LiClO4, this hybrid attains a large NH3 yield rate and a high Faradaic efficiency of 27.3 µg·h−1·mg−1cat. and 14.6% at −0.4 V vs. reversible hydrogen electrode, respectively, rivalling the current efficiency of all Fe-based NRR electrocatalysts in aqueous media. It also shows strong durability during the electrolytic process.
相似文献Realizing the reduction of N2 to NH3 at low temperature and pressure is always the unremitting pursuit of scientists and then electrochemical nitrogen reduction reaction offers an intriguing alternative. Here, we develop a feasible way, gamma irradiation, for constructing defective structure on the surface of WO3 nanosheets, which is clearly observed at the atomic scale by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The abundant oxygen vacancies ensure WO3 nanosheets with a Faradaic efficiency of 23% at −0.3 V vs. RHE. Moreover, we start from the regulation of the surface state to suppress proton availability towards hydrogen evolution reaction (HER) on the active site and thus boost the selectivity of nitrogen reduction.
相似文献Electronic sensors based on biomaterials can lead to novel green technologies that are low cost, renewable, and eco-friendly. Here we demonstrate bioelectronic ammonia sensors made from protein nanowires harvested from the microorganism Geobacter sulfurreducens. The nanowire sensor responds to a broad range of ammonia concentrations (10 to 106 ppb), which covers the range relevant for industrial, environmental, and biomedical applications. The sensor also demonstrates high selectivity to ammonia compared to moisture and other common gases found in human breath. These results provide a proof-of-concept demonstration for developing protein nanowire based gas sensors for applications in industry, agriculture, environmental monitoring, and healthcare.
相似文献The K metal batteries are emerged as promising alternatives beyond commercialized Li-ion batteries. However, suppressing uncontrolled dendrite is crucial to the accomplishment of K metal batteries. Herein, an oxygen-rich treated carbon cloth (TCC) has been designed as the K plating host to guide K homogeneous nucleation and suppress the dendrite growth. Both density function theory calculations and experimental results demonstrate that abundant oxygen functional groups as K-philic sites on TCC can guide K nucleation and deposition homogeneously. As a result, the TCC electrode exhibits an ultra-long-life over 800 cycles at high current density of 3.0 mA·cm−2 for 3.0 mA·h·cm−2. Furthermore, the symmetrical cells can run stably for 2,000 h with low over-potential less than 20 mV at 1.0 mA·cm−2 for 1.0 mA·h·cm−2. Even at a higher current of 5.0 mA·cm−2, the TCC electrode can still stably cycle for 1,400 h.
相似文献The low specific capacity and sluggish electrochemical reaction kinetics greatly block the development of sodium-ion batteries (SIBs). New high-performance electrode materials will enhance development and are urgently required for SIBs. Herein, we report the preparation of supersaturated bridge-sulfur and vanadium co-doped MoS2 nanosheet arrays on carbon cloth (denoted as V-MoS2+x/CC). The bridge-sulfur in MoS2 has been created as a new active site for greater Na+ storage. The vanadium doping increases the density of carriers and facilitates accelerated electron transfer. The synergistic dual-doping effects endow the V-MoS2+x/CC anodes with high sodium storage performance. The optimized V-MoS2.49/CC gives superhigh capacities of 370 and 214 mAh·g−1 at 0.1 and 10 A·g−1 within 0.4−3.0 V, respectively. After cycling 3,000 times at 2 A·g−1, almost 83% of the reversible capacity is maintained. The findings indicate that the electrochemical performances of metal sulfides can be further improved by edge-engineering and lattice-doping co-modification concept.
相似文献Oligo(p-phenyleneethynylene)s (OPEs) end-capped with (alkynyl)bis(diphosphine)ruthenium and thiol/thiolate groups stabilize ca. 2 nm diameter gold nanoparticles (AuNPs). The morphology, elemental composition and stability of the resultant organometallic OPE/AuNP hybrid materials have been defined using a combination of molecular- and nano-material chacterization techniques. The hybrids display long-term stability in solution (more than a month), good solubility in organic solvents, reversible ruthenium-centered oxidation, and transparency beyond 800 nm, and possess very strong nonlinear absorption activity at the first biological window, and unprecedented two-photon absorption activity in the second biological window (σ2 up to 38,000 GM at 1,050 nm).
相似文献Electrochemical water splitting (EWS) is a highly clean and efficient method for high-purity hydrogen production. Unfortunately, EWS suffers from the sluggish and complex oxygen evolution reaction (OER) kinetics at anode. At present, the efficient, stable, and low-cost non-precious metal based OER electrocatalyst is still a great and long-term challenge for the future industrial application of EWS technology. Herein, we develop a simple and fast approach for gram-scale synthesis of flower-like cobalt-based layered double hydroxides nanosheet aggregates by ultrasonic synthesis, which show outstanding electrocatalytic performance for the oxygen evolution reaction in alkaline media, such as preeminent stability, small overpotential of 300 mV at 10 mA·cm−2 and small Tafel slope of 110 mV·dec−1.
相似文献Porous graphitic carbon nanorings (PGCNs) are proposed by smart catalytic graphitization of nano-sized graphene quantum dots (GQDs). The as-prepared PGCNs show unique ring-like morphology with diameter around 10 nm, and demonstrate extraordinary mesoporous structure, controllable graphitization degree and highly defective nature. The mechanism from GQDs to PGCNs is proven to be a dissolution-precipitation process, undergoing the procedure of amorphous carbon, intermediate phase, graphitic carbon nanorings and graphitic carbon nanosheets. Further, the relationship between particles size of GQDs precursor and graphitization degree of PGCNs products is revealed. The unique microstructure implies PGCNs a broad prospect for energy storage application. When applied as negative electrode materials in dual-carbon lithium-ion capacitors, high energy density (77.6 Wh·kg−1) and super long lifespan (89.5% retention after 40,000 cycles at 5.0 A·g−1) are obtained. The energy density still maintains at 24.5 Wh·kg−1 even at the power density of 14.1 kW·kg−1, demonstrating excellent rate capability. The distinct microstructure of PGCNs together with the strategy for catalytic conversion from nanocarbon precursors to carbon nanorings opens a new window for carbon materials in electrochemical energy storage.
相似文献The development of high-efficiency peroxidase mimetics is highly desirable in view of high cost and low stability of natural enzymes. From the perspective of mimicking active site microenvironment at low cost, we herein report a novel histidine-functionalized graphene quantum dot (His-GQD)/hemin complex, which exhibits the highest catalytic rate for the peroxidase-based chromogenic reaction among the hemin-containing mimetics reported so far. Also, our peroxidase mimetic shows excellent tolerance to strongly acidic conditions and can function in a wide temperature range. Lineweaver-Burk plots and comprehensive electron paramagnetic resonance analysis reveal a ping-pong type catalytic mechanism for this mimetic. In addition, His-GQD/hemin demonstrates high efficiency and accuracy in detecting H2O2 and blood glucose. Our work provides an effective design of artificial enzymes for practical applications.
相似文献Highly efficient photo-assisted electrocatalysis for methanol oxidation reaction (MOR) realizes the conversion of solar and chemical energy into electric energy simultaneously. Here we report a Pt-MXene-TiO2 composite for highly efficient MOR via a photoactive cascaded electro-catalytic process. With light (UV and visible light) irradiation, MXene-TiO2 serves as the photo active centre (photoinduced hole) to activate the methanol molecules, while Pt particles are the active centre for the following electro-catalytic oxidation of those activated methanol molecules. Pt-MXene-TiO2 catalyst exhibits a lower onset potential (0.33 V) and an impressive mass activity of 2,750.42 mA·mg−1Pt under light illumination. It represents the highest MOR activity ever reported for photo-assisted electrocatalysts. Pt-MXene-TiO2 also shows excellent CO tolerance ability and stability, in which, after long-term (5,000 s) reaction, still keeps a high mass activity of 1,269.81 mA·mg−1Pt (62.66% of its initial activity). The photo-electro-catalytic system proposed in this work offers novel opportunities for exploiting photo-assisted enhancement of highly efficient and stable catalysts for MOR.
相似文献Two-dimensional nanosheet membranes with responsive nanochannels are appealing for controlled mass transfer/separation, but limited by everchanging thicknesses arising from unstable interfaces. Herein, an interfacially stable, thermo-responsive nanosheet membrane is assembled from twin-chain stabilized metal-organic framework (MOF) nanosheets, which function via two cyclic amide-bearing polymers, thermo-responsive poly(N-vinyl caprolactam) (PVCL) for adjusting channel size, and non-responsive polyvinylpyrrolidone for supporting constant interlayer distance. Owing to the microporosity of MOF nanosheets and controllable interface wettability, the hybrid membrane demonstrates both superior separation performance and stable thermo-responsiveness. Scattering and correlation spectroscopic analyses further corroborate the respective roles of the two polymers and reveal the microenvironment changes of nanochannels are motivated by the dehydration of PVCL chains.
相似文献Nanoparticles (NPs) which are innovation and research focus in drug delivery systems, still have some disadvantages limiting its application in clinical use, such as short circulation time, recognition and clearance by reticuloendothelial system (RES) and passive targeting in certain organs. However, the recent combination of natural components and nanotechnology has offered new solutions to address these problems. A novel biomimetic platform consisting of nanoparticle core and membrane shell, such as cell membrane, exosome or vesicle vastly improves properties of nanoparticles. These coated nanoparticles can replicate the unique functions of the membrane, such as prolonged blood circulation, active targeting capability and enhanced internalization. In this review, we focus on the newest development of biological-camouflaged nanoparticles and mainly introduce its application related to cancer therapy and toll-like receptor.
相似文献Potassium-ion batteries are regarded as the low-cost alternative to lithium-ion batteries. However, their development is hampered by the lack of suitable electrode materials. In this work, we demonstrate that MoS2 with expanded interlayers represents a promising candidate for the electrochemical storage of potassium ions. Hierarchical interlayer-expanded MoS2 assemblies supported on carbon nanotubes are prepared via a straightforward solution method. The increased interlayer spacing not only enables the better accommodation of foreign ions, but also lowers the diffusion energy barrier and improves diffusion kinetics of ions. When investigated as the anode material of potassium ion batteries, our interlayer-expanded MoS2 assemblies exhibit an excellent electrochemical performance with large capacity (up to ∼ 520 mAhg−1), good rate capability (∼ 310 mAhg−1 at 1,000 mAg−1) and impressive cycling stability, superior to most competitors.
相似文献Printable elastic conductors promote the wide application of consumable electronic textiles (e-textiles) for pervasive healthcare monitoring and wearable computation. To assure a clean appearance, the e-textiles require a washing process to clean up the dirt after daily use. Thus, it is crucial to develop low-cost printable elastic conductors with strong adhesion to the textiles. Here, we report a composite elastic conductor based on Ag nanowires (NWs) and polyurethane elastomer. The composite could be dispersed into ink and easily printed onto textiles. One-step print could form robust conductive coatings without sealing on the textiles. Interestingly, the regional concentration of Ag NWs within the polyurethane matrix was observed during phase inversion, endowing the elastic conductor with a low percolation threshold of 0.12 vol.% and high conductivity of 3,668 S·cm−1. Thanks to the high adhesion of the elastic conductors, the resulted e-textiles could withstand repeated stretching, folding, and machine washing (20 times) without obvious performance decay, which reveals its potential application in consumable e-textiles.
相似文献The rapid development of solar cells based on lead halide perovskites (LHPs) has prompted very active research activities in other closely-related fields. Colloidal nanostructures of such materials display superior optoelectronic properties. Especially, one-dimensional (1D) LHPs nanowires show anisotropic optical properties when they are highly oriented. However, the ionic nature makes them very sensitive to external environment, limiting their large scale practical applications. Here, we introduce an amphiphilic block copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-P4VP), to chemically modify the surface of colloidal CsPbBr3 nanowires. The resulting core-shell nanowires show enhanced photoluminescent emission and good colloidal stability against water. Taking advantage of the stability enhancement, we further applied a modified Langmuir-Blodgett technique to assemble monolayers of highly aligned nanowires, and studied their anisotropic optical properties.
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