Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 167
Filtrar
1.
Nano Lett ; 23(3): 812-819, 2023 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-36579841

RESUMEN

Converting vapor precursors to solid nanostructures via a liquid noble-metal seed is a common vapor deposition principle. However, such a noble-metal-seeded process is excluded from the crystalline halide perovskite synthesis, mainly hindered by the growth mechanism shortness. Herein, powered by a spontaneous exothermic nucleation process (ΔH < 0), the Au-seeded CsPbI3 nanowires (NWs) growth is realized based on a vapor-liquid-solid (VLS) growth mode. It is energetically favored that the Au seeds are reacted with a Pb vapor precursor to form molten Au-Pb droplets at temperatures down to 212 °C, further triggering the low-temperature VLS growth of CsPbI3 NWs. More importantly, this Au-seeded process reduces in-bandgap trap states and consequently avoids Shockley-Read-Hall recombination, contributing to outstanding photodetector performances. Our work extends the powerful Au-seeded VLS growth mode to the emerging halide perovskites, which will facilitate their nanostructures with tailored material properties.

2.
Small ; 19(46): e2303716, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37475506

RESUMEN

Harvesting electrical energy from water and moisture has emerged as a novel ecofriendly energy conversion technology. Herein, a multifunctional asymmetric polyaniline/carbon nanotubes/poly(vinyl alcohol) (APCP) that can produce electric energy from both saline water and moisture and generate fresh water simultaneously is developed. The constructed APCP possesses a negatively charged porous structure that allows continuous generation of protons and ion diffusion through the material, and a hydrophilicity-hydrophobic interface which results in a constant potential difference and sustainable output. A single APCP can maintain stable output for over 130 h and preserve a high voltage of 0.61 V, current of 81 µA, and power density of 82.4 µW cm-3 with 0.15 cm3 unit size in the water-induced electricity generation process. When harvesting moisture energy, the APCP creates dry-wet asymmetries and triggers the spontaneous development of electrical double layer with a current density of 1.25 mA cm-3 , sufficient to power small electronics. A device consisting of four APCP can generate stable electricity of 3.35 V and produce clean water with an evaporation rate of 2.06 kg m-2  h-1 simultaneously. This work provides insights into the fabrication of multifunctional fabrics for multisource energy harvesting and simultaneous solar steam generation.

3.
Small ; 19(10): e2205959, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36564359

RESUMEN

Metal-free 2D phosphorus-based materials are emerging catalysts for ammonia (NH3 ) production through a sustainable electrochemical nitrogen reduction reaction route under ambient conditions. However, their efficiency and stability remain challenging due to the surface oxidization. Herein, a stable phosphorus-based electrocatalyst, silicon phosphide (SiP), is explored. Density functional theory calculations certify that the N2 activation can be realized on the zigzag Si sites with a dimeric end-on coordinated mode. Such sites also allow the subsequent protonation process via the alternating associative mechanism. As the proof-of-concept demonstration, both the crystalline and amorphous SiP nanosheets (denoted as C-SiP NSs and A-SiP NSs, respectively) are obtained through ultrasonic exfoliation processes, but only the crystalline one enables effective and stable electrocatalytic nitrogen reduction reaction, in terms of an NH3 yield rate of 16.12 µg h-1  mgcat. -1 and a Faradaic efficiency of 22.48% at -0.3 V versus reversible hydrogen electrode. The resistance to oxidization plays the decisive role in guaranteeing the NH3 electrosynthesis activity for C-SiP NSs. This surface stability endows C-SiP NSs with the capability to serve as appealing electrocatalysts for nitrogen reduction reactions and other promising applications.

4.
Macromol Rapid Commun ; 44(10): e2300065, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36960581

RESUMEN

Recent advances in the cell structure regulation and performances improvement of porous poly(lactic acid) materials (PPMs) are systematically reviewed in this feature article. First, the typical processing methods, including template method, non-solvent induced phase separation, freeze-drying, and supercritical CO2  foaming, of PPMs are introduced emphatically. Their various cell morphologies by different processing methods are summarized: finger-like, honeycomb-like, fiber-like, through cell, open cell, closed cell, ball-like, and flower-like. Meanwhile, the transformation among different cell morphologies as well as the changes in cell size and cell density, having impact on the performances, is described. Second, the influence of stereo-complex crystals on the cell structure of PPMs is emphatically reviewed. Furthermore, the relationships between cell structure and properties that includes mechanical properties, thermal stability, heat insulation, and hydrophobicity, are elaborated. Eventually, the issues of PPMs worthy of further study are discussed.


Asunto(s)
Ácido Láctico , Ingeniería de Tejidos , Porosidad , Ingeniería de Tejidos/métodos , Ensayo de Materiales , Ácido Láctico/química , Poliésteres
5.
J Chem Phys ; 158(17)2023 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-37125721

RESUMEN

A wide spectrum of state-of-the-art characterization techniques have been devised to monitor the electrode-electrolyte interface that dictates the performance of electrochemical devices. However, coupling multiple characterization techniques to realize in situ multidimensional analysis of electrochemical interfaces remains a challenge. Herein, we presented a hyphenated differential electrochemical mass spectrometry and attenuated total reflection surface enhanced infrared absorption spectroscopy analytical method via a specially designed electrochemical cell that enables a simultaneous detection of deposited and volatile interface species under electrochemical reaction conditions, especially suitable for non-aqueous, electrolyte-based energy devices. As a proof of concept, we demonstrated the capability of the homemade setup and obtained the valuable reaction mechanisms, by taking the tantalizing reactions in non-aqueous lithium-ion batteries (i.e., oxidation and reduction processes of carbonate-based electrolytes on Li1+xNi0.8Mn0.1Co0.1O2 and graphite surfaces) and lithium-oxygen batteries (i.e., reversibility of the oxygen reaction) as model reactions. Overall, we believe that the coupled and complementary techniques reported here will provide important insights into the interfacial electrochemistry of energy storage materials (i.e., in situ, multi-dimensional information in one single experiment) and generate much interest in the electrochemistry community and beyond.

6.
Small ; 18(43): e2107773, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35934834

RESUMEN

The high cost and scarcity of lithium resources have prompted researchers to seek alternatives to lithium-ion batteries. Among emerging "Beyond Lithium" batteries, rechargeable aluminum-ion batteries (AIBs) are yet another attractive electrochemical storage device due to their high specific capacity and the abundance of aluminum. Although the current electrochemical performance of nonaqueous AIBs is better than aqueous AIBs (AAIBs), AAIBs have recently gained attention due to their low cost and enhanced safety. Extensive efforts are devoted to developing AAIBs in the last few years. Yet, it is still challenging to achieve stable electrodes with good electrochemical performance and electrolytes without side reactions. This review summarizes the recent progress in the exploration of anode and cathode materials and the selection of electrolytes of AAIBs. Lastly, the main challenges and future research outlook of high-performance AAIBs are also presented.

7.
Small ; 18(16): e2107885, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-35261150

RESUMEN

Exploring catalyst reconstruction under the electrochemical condition is critical to understanding the catalyst structure-activity relationship as well as to design effective electrocatalysts. Herein, a PbF2 nanocluster is synthesized and its self-reconstruction under the CO2 reduction condition is investigated. F- leaching, CO2 -saturated environment, and application of a cathodic potential induce self-reconstruction of PbF2 to Pb3 (CO3 )2 (OH)2 , which effectively catalyze the CO2 reduction to formate. The in situ formed Pb3 (CO3 )2 (OH)2 discloses >80% formate Faradaic efficiencies (FEs) across a broad range of potentials and achieves a maximum formate FE of ≈90.1% at -1.2 V versus reversible hydrogen electrode (RHE). Kinetic studies show that the CO2 reduction reaction (CO2 RR) on the Pb3 (CO3 )2 (OH)2 is rate-limited at the CO2 protonation step, in which proton is supplied by bicarbonate (HCO3 - ) in the electrolyte. To improve the CO2 RR kinetics, the Pb3 (CO3 )2 (OH)2 is further doped with Pd (4 wt%) to enhance its HCO3 - adsorption, which leads to accelerated protonation of CO2 . Therefore, the Pd-Pb3 (CO3 )2 (OH)2 (4 wt%) reveals higher formate FEs of >90% from -0.8 to -1.2 V versus RHE and reaches a maximum formate FE of 96.5% at -1.2 V versus RHE with a current density of ≈13 mA cm-2 .

8.
Soft Matter ; 18(27): 5052-5059, 2022 Jul 13.
Artículo en Inglés | MEDLINE | ID: mdl-35758137

RESUMEN

Recently, soft actuators have attracted considerable interest owing to their biomimetic performance. Unfortunately, it remains a great challenge to fabricate multi-stimuli-responsive soft actuators by a facile but low-cost method. Herein, a thermoplastic film with bilayered architecture was designed and fabricated by a one-step method. This bilayered thermoplastic film can act as a soft actuator, demonstrating versatile shape-programmable performance in response to acetone vapor exposure and temperature change. Interestingly, diverse biomimetic devices including a worm-like self-walker, crawler-type robot and soft gripper can be realized, which highlights its promising applications in biomimetic robots, artificial muscles and automatic devices. Considering the one-step preparation process and the low-cost raw materials, this approach can be cost-effectively scaled up for practical production.

9.
Soft Matter ; 18(35): 6572-6581, 2022 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-35959627

RESUMEN

New questions and conjectures are raised on the crystal-crystal phase transition of isotactic polybutene-1 (iPB-1) containing nanofiller in the flow field. In this work, we investigate the phase transition from flow-induced oriented form II to I in iPB-1 blends with multi-walled carbon nanotubes (MWCNTs) with a homemade two-drum extensional rheometer combined with in situ wide-angle X-ray diffraction (WAXD) measurements. The MWCNTs show a limited promoting effect on the phase transition kinetics under quiescent conditions, while the phase transition kinetic is highly accelerated with the impose of melt-extension. When the loading extension strain is 0.5 or 2.0, the half time of phase transition (t1/2) is shortened from tens of hours to a few hours, depending on the melt-extension strain and the MWCNTs content in iPB-1. When the extension strain increases to 3.5, t1/2 decreases to about 30 min, which is independent of the MWCNTs content in all iPB-1 blends except in blends with MWCNTs content of 1%, where the phase transition rate in the middle and late stages is restrained. It's speculated that flow-induced molecular orientation or shish-kebab morphology affects the internal stress or stress transfer. The addition of a nanofiller enlarged the effect of melt-extension through strengthening the localized intensity of flow field. In general, the combination of nanofiller and melt-extension can obviously promote the phase transition kinetics.

10.
Nanotechnology ; 33(40)2022 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-35764051

RESUMEN

The electro-mechanical response of conductive carbon-nanotube(CNT)-polymer composites is vital when they are used as smart-sensing materials. Clarifying the variation trend of resistance with strain is the key to design and regulate the piezoresistive property of such material. Here, we present some finite element simulations to predict the electro-mechanical response using a geometrical model comprising two hollow cylindrical CNTs and a cuboid matrix. The electrical contact between CNTs is represented by some elements which account for quantum tunnelling effects and capture the sensitivity of conductivity to separation. Different from classical simulations using solid model or one-dimensional beam model, in which the tunnelling resistance between two CNTs changes monotonously with strain, the results in this work show that the trend is non-monotonic in some cases, i.e. it increases at first and then decreases with the uniaxial compressive strain when the elastic modulus of the matrix is high. In addition, factors affecting the different variation trends are discussed in details, which include geometric model, elastic modulus and Poisson's ratio of the matrix, and orientation angle.

11.
Environ Sci Technol ; 56(16): 11818-11826, 2022 Aug 16.
Artículo en Inglés | MEDLINE | ID: mdl-35925900

RESUMEN

Solar-driven interfacial evaporation is considered to be one of the promising and efficient ways of producing clean water in recent years. However, it remains a challenge to develop solar evaporation devices with high solar evaporation rates and salt-free blocking properties. Here, a porous solar evaporator with directed water transport and salt-free desalination through excellent photothermal conversion and purposefully guided migration of the salt solution was developed. The designed porous photothermal sponge with the synergistic effect of MXene and polypyrrole can achieve evaporation rates of 1.47 and 2.27 kg m-2 h-1, respectively, in the capillary model and siphon model water-transporting solar evaporation devices. More interestingly, the designed zigzag-shaped device with an evaporation rate of 2.45 kg m-2 h-1 was achieved. In addition, the evaporator can operate stably under 9 h in the siphon model solar evaporation device and achieves the effect of salt-free desalination. The above design provides a good strategy for solar-powered desalination applications.

12.
Rare Metals ; 41(4): 1129-1141, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35068851

RESUMEN

Abstract: The coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed severe threats to human health, public safety, and the global economy. Metal nutrient elements can directly or indirectly take part in human immune responses, and metal-related drugs have served as antiviral drugs and/or enzyme inhibitors for many years, providing potential solutions to the prevention and treatment of COVID-19. Metal-based drugs are currently under a variety of chemical structures and exhibit wide-range bioactivities, demonstrating irreplaceable advantages in pharmacology. This review is an intention to summarize recent progress in the prevention and treatment strategies against COVID-19 from the perspective of metal pharmacology. The current and potential utilization of metal-based drugs is briefly introduced. Specifically, metallohydrogels that have been shown to present superior antiviral activities are stressed in the paper as potential drugs for the treatment of COVID-19.

13.
Small ; 17(9): e1903194, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31544320

RESUMEN

High-energy batteries with low cost are urgently needed in the field of large-scale energy storage, such as grid systems and renewable energy sources. Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) with alloy-based anodes provide huge potential due to their earth abundance, high capacity, and suitable working potential, and are recognized as attractive alternatives for next-generation batteries system. Although some important breakthroughs have been reported, more significant improvements are still required for long lifetime and high energy density. Herein, the latest progress for alloy-based anodes for SIBs and PIBs is summarized, mainly including Sn, Sb, Ge, Bi, Si, P, and their oxides, sulfides, selenides, and phosphides. Specifically, the material designs for the desired Na+ /K+ storage performance, phase transform, ionic/electronic transport kinetics, and specific chemical interactions are discussed. Typical structural features and research strategies of alloy-based anodes, which are used to facilitate processes in battery development for SIBs and PIBs, are also summarized. The perspective of future research of SIBs and PIBs is outlined.

14.
Small ; 17(31): e2100542, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-34174162

RESUMEN

Electronic skins (e-skins) have attracted great attention for their applications in disease diagnostics, soft robots, and human-machine interaction. The integration of high sensitivity, low detection limit, large stretchability, and multiple stimulus response capacity into a single e-skin remains an enormous challenge. Herein, inspired by the structure of nacre, an ultra-stretchable and multifunctional e-skin with tunable strain detection range based on nacre-mimetic multi-layered silver nanowires /reduced graphene oxide /thermoplastic polyurethane mats is fabricated. The e-skin possesses extraordinary strain response performance with a tunable detection range (50 to 200% strain), an ultralow response limit (0.1% strain), a high sensitivity (gauge factor up to 1902.5), a fast response time (20 ms), and an excellent stability (stretching/releasing test of 11 000 cycles). These excellent response behaviors enable the e-skin to accurately monitor full-range human body motions. Additionally, the e-skin can detect relative humidity quickly and sensitively through a reversible physical adsorption/desorption of water vapor, and the assembled e-skin array exhibits excellent performance in noncontact sensing. The tunable and multifunctional e-skins show promising applications in motion monitoring and contact-noncontact human machine interaction.


Asunto(s)
Nácar , Nanocables , Dispositivos Electrónicos Vestibles , Electrónica , Humanos , Movimiento (Física)
15.
Small ; 17(23): e2100442, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33891799

RESUMEN

Although there are recent advances in many areas of quasi-2D halide perovskites, photodetectors based on these materials still cannot achieve satisfactory performance for practical applications where high responsivity, fast response, self-powered nature, and excellent mechanical flexibility are urgently desired. Herein, utilizing one-step spin-coating method, self-assemble quasi-2D perovskite films with graded phase distribution in the order of increasing number of metal halide octahedral layers are successfully prepared. Gradient type-II band alignments along the out-of-plane direction of perovskites with spontaneous separation of photo-generated electrons and holes are obtained and then employed to construct self-powered vertical-structure photodetectors for the first time. Without any driving voltage, the device exhibits impressive performance with the responsivity up to 444 mA W-1 and ultrashort response time down to 52 µs. With a bias voltage of 1.5 V, the device responsivity becomes 3463 mA W-1 with the response speed as fast as 24 µs. Importantly, the device's mechanical flexibility is greatly enhanced since the photocurrent prefers flowing through the metal halide octahedral layers between the top and bottom contact electrodes in the vertical device structure, being more tolerant to film damage. These results evidently indicate the potential of graded quasi-2D perovskite phases for next-generation optoelectronic devices.

16.
Small ; 17(7): e2006860, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33480477

RESUMEN

2D metal phosphide loop-sheet heterostructures are controllably synthesized by edge-topological regulation, where Ni2 P nanosheets are edge-confined by the N-doped carbon loop, containing ultrafine NiFeP nanocrystals (denoted as NiFeP@NC/Ni2 P). This loop-sheet feature with lifted-edges prevents the stacking of nanosheets and induces accessible open channels for catalytic site exposure and gas bubble release. Importantly, these NiFeP@NC/Ni2 P hybrids exhibit a remarkable oxygen evolution activity with an overpotential of 223 mV at 20 mA cm-2 and a Tafel slope of 46.1 mV dec-1 , constituting the record-high performance among reported metal phosphide electrocatalysts. The NiFeP@NC/Ni2 P hybrids are also employed as both anode and cathode to achieve an alkaline electrolyzer for overall water splitting, delivering a current density of 10 mA cm-2 with a voltage of 1.57 V, comparable to that of the commercial Pt/C||RuO2 couple (1.56 V). Moreover, a photovoltaic-electrolysis coupling system can as well be effectively established for robust overall water splitting. Evidently, this ingenious protocol would expand the toolbox for designing efficient 2D nanomaterials for practical applications.

17.
Soft Matter ; 17(48): 10829-10838, 2021 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-34796898

RESUMEN

Lamellar crystal-dominated (LCD) surfaces hold great superiority and broad prospects in polymer surface engineering. The key to this is avoiding the formation of an amorphous phase in the interlamellar region. Here we give a first report of achieving LCD surfaces of polyethylene films via melt stretching-induced free surface crystallization. We demonstrate that the resultant surface is constructed directly by orientated and edge-on lamellae within a surface depth of tens to hundreds of nanometers, while the normally existing amorphous phase is avoided. The crystallization-driven formation of the LCD surface has been ascribed to the heterogeneous chain dynamics of a melt free surface, that is, high chain mobility, low viscosity and loose chain entanglement, which facilitates the complete chain disentanglement during crystallization. In addition, we confirm that the surface morphology is controllable with respect to lamellar orientation, spacing and depth by changing the melt stretching strain or quenching the deformed melt. Meanwhile, owing to a possible kinetics competition between crystallization and chain disentanglement, the structural spacing of surface lamellae holds a positive correlation with the lamellar depth. Since free surface effects are immanent in polymer materials, the currently proposed melt processing strategy is demonstrated to be transferable to other semicrystalline polymers.

18.
Chem Soc Rev ; 49(7): 2196-2214, 2020 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-32133479

RESUMEN

Electricity-driven water splitting can facilitate the storage of electrical energy in the form of hydrogen gas. As a half-reaction of electricity-driven water splitting, the oxygen evolution reaction (OER) is the major bottleneck due to the sluggish kinetics of this four-electron transfer reaction. Developing low-cost and robust OER catalysts is critical to solving this efficiency problem in water splitting. The catalyst design has to be built based on the fundamental understanding of the OER mechanism and the origin of the reaction overpotential. In this article, we summarize the recent progress in understanding OER mechanisms, which include the conventional adsorbate evolution mechanism (AEM) and lattice-oxygen-mediated mechanism (LOM) from both theoretical and experimental aspects. We start with the discussion on the AEM and its linked scaling relations among various reaction intermediates. The strategies to reduce overpotential based on the AEM and its derived descriptors are then introduced. To further reduce the OER overpotential, it is necessary to break the scaling relation of HOO* and HO* intermediates in conventional AEM to go beyond the activity limitation of the volcano relationship. Strategies such as stabilization of HOO*, proton acceptor functionality, and switching the OER pathway to LOM are discussed. The remaining questions on the OER and related perspectives are also presented at the end.

19.
Angew Chem Int Ed Engl ; 60(50): 26233-26237, 2021 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-34586693

RESUMEN

With ever-increasing energy consumption and continuous rise in atmospheric CO2 concentration, electrochemical reduction of CO2 into chemicals/fuels is becoming a promising yet challenging solution. Sn-based materials are identified as attractive electrocatalysts for the CO2 reduction reaction (CO2 RR) to formate but suffer from insufficient selectivity and activity, especially at large cathodic current densities. Herein, we demonstrate that Cu-doped SnS2 nanoflowers can undergo in situ dynamic restructuring to generate catalytically active S-doped Cu/Sn alloy for highly selective electrochemical CO2 RR to formate over a wide potential window. Theoretical thermodynamic analysis of reaction energetics indicates that the optimal electronic structure of the Sn active site can be regulated by both S-doping and Cu-alloying to favor formate formation, while the CO and H2 pathways will be suppressed. Our findings provide a rational strategy for electronic modulation of metal active site(s) for the design of active and selective electrocatalysts towards CO2 RR.

20.
Angew Chem Int Ed Engl ; 60(20): 11481-11486, 2021 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-33686746

RESUMEN

High initial coulombic efficiency is highly desired because it implies effective interface construction and few electrolyte consumption, indicating enhanced batteries' life and power output. In this work, a high-capacity sodium storage material with FeS2 nanoclusters (≈1-2 nm) embedded in N, S-doped carbon matrix (FeS2 /N,S-C) was synthesized, the surface of which displays defects-repaired characteristic and detectable dot-matrix distributed Fe-N-C/Fe-S-C bonds. After the initial discharging process, the uniform ultra-thin NaF-rich (≈6.0 nm) solid electrolyte interphase was obtained, thereby achieving verifiable ultra-high initial coulombic efficiency (≈92 %). The defects-repaired surface provides perfect platform, and the catalysis of dot-matrix distributed Fe-N-C/Fe-S-C bonds to the rapid decomposing of NaSO3 CF3 and diethylene glycol dimethyl ether successfully accelerate the building of two-dimensional ultra-thin solid electrolyte interphase. DFT calculations further confirmed the catalysis mechanism. As a result, the constructed FeS2 /N,S-C provides high reversible capacity (749.6 mAh g-1 at 0.1 A g-1 ) and outstanding cycle stability (92.7 %, 10 000 cycles, 10.0 A g-1 ). Especially, at -15 °C, it also obtains a reversible capacity of 211.7 mAh g-1 at 10.0 A g-1 . Assembled pouch-type cell performs potential application. The insight in this work provides a bright way to interface design for performance improvement in batteries.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA