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1.
ACS Nano ; 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32392033

RESUMO

The aqueous zinc ion battery has emerged as a promising alternative technology for large-scale energy storage due to its low cost, natural abundance, and high safety features. However, the sluggish kinetics stemming from the strong electrostatic interaction of divalent zinc ions in the host crystal structure is one of challenges for highly efficient energy storage. Oxygen vacancies (VO••), in the present work, lead to a larger tunnel structure along the b axis, which improves the reactive kinetics and enhances Zn-ion storage capability in VO2 (B) cathode. DFT calculations further support that VO•• in VO2 (B) result in a narrower bandgap and lower Zn ion diffusion energy barrier compared to those of pristine VO2 (B). VO••-rich VO2 (B) achieves a specific capacity of 375 mAh g-1 at a current density of 100 mA g-1 and long-term cyclic stability with retained specific capacity of 175 mAh g-1 at 5 A g-1 over 2000 cycles (85% capacity retention), higher than that of VO2 (B) nanobelts (280 mAh g-1 at 100 mA g-1 and 120 mAh g-1 at 5 A g-1, 65% capacity retention).

2.
Artigo em Inglês | MEDLINE | ID: mdl-32011118

RESUMO

Because of their attractive photoelectrical properties, perovskite-phase, CsPbX3 (X = I, Br, or Cl) materials have recently gained attention for their applications in resistive switching (RS) memories. However, phase transition of the CsPbI3 from perovskite (cubic phase) to nonperovskite (orthorhombic phase) at room temperature is problematic; it remains a challenge to apply nonperovskite CsPbI3 in RS memories. In the present work, a polymethylmethacrylate (PMMA)-assisted deposition method for nonperovskite CsPbI3 is introduced to fabricate a composite film of CsPbI3 with PMMA (PMMA@CsPbI3) with a smooth surface morphology on fluorine-doped tin oxide (FTO) substrates. Devices with a Ag/PMMA@CsPbI3/FTO architecture show nonvolatile RS characteristics with an ON/OFF ratio around 102, endurance over 500 cycles, and a retention time of 103 s. Analyses suggested that a Schottky barrier at the Ag/PMMA@CsPbI3 interface and a bias-induced migration of Ag ions within the composite films are responsible for the RS operation. This is the first record for RS devices based on nonperovskite CsPbI3, and it may bring the future research on nonperovskite CsPbI3 applied in RS memory devices some new inspiration..

3.
Adv Mater ; : e1905245, 2020 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-31975460

RESUMO

The ever-increasing demand for clean sustainable energy has driven tremendous worldwide investment in the design and exploration of new active materials for energy conversion and energy-storage devices. Tailoring the surfaces of and interfaces between different materials is one of the surest and best studied paths to enable high-energy-density batteries and high-efficiency solar cells. Metal-halide perovskite solar cells (PSCs) are one of the most promising photovoltaic materials due to their unprecedented development, with their record power conversion efficiency (PCE) rocketing beyond 25% in less than 10 years. Such progress is achieved largely through the control of crystallinity and surface/interface defects. Rechargeable batteries (RBs) reversibly convert electrical and chemical potential energy through redox reactions at the interfaces between the electrodes and electrolyte. The (electro)chemical and optoelectronic compatibility between active components are essential design considerations to optimize power conversion and energy storage performance. A focused discussion and critical analysis on the formation and functions of the interfaces and interphases of the active materials in these devices is provided, and prospective strategies used to overcome current challenges are described. These strategies revolve around manipulating the chemical compositions, defects, stability, and passivation of the various interfaces of RBs and PSCs.

4.
Adv Sci (Weinh) ; 6(21): 1901591, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31728291

RESUMO

Formamidinium (FA) lead halide (α-FAPbI3) perovskites are promising materials for photovoltaic applications because of their excellent light harvesting capability (absorption edge 840 nm) and long carrier diffusion length. However, it is extremely difficult to prepare a pure α-FAPbI3 phase because of its easy transformation into a nondesirable δ-FAPbI3 phase. In the present study, a "perovskite" template (MAPbI3-FAI-PbI2-DMSO) structure is used to avoid and suppress the formation of δ-FAPbI3 phases. The perovskite structure is formed via postdeposition involving the treatment of colloidal MAI-PbI2-DMSO film with FAI before annealing. In situ X-ray diffraction in vacuum shows no detectable δ-FAPbI3 phase during the whole synthesis process when the sample is annealed from 100 to 180 °C. This method is found to reduce defects at grain boundaries and enhance the film quality as determined by means of photoluminescence mapping and Kelvin probe force microscopy. The perovskite solar cells (PSCs) fabricated by this method demonstrate a much-enhanced short-circuit current density ( J sc) of 24.99 mA cm-2 and a power conversion efficiency (PCE) of 21.24%, which is the highest efficiency reported for pure FAPbI3, with great stability under 800 h of thermal ageing and 500 h of light soaking in nitrogen.

5.
ACS Appl Mater Interfaces ; 11(44): 41363-41373, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31599565

RESUMO

Layered tin monosulfide (SnS) is a promising anode material for sodium-ion batteries because of its high theoretical capacity of 1020 mA h g-1. Its large interlayer spacing permits fast sodium-ion transport, making it a viable candidate for sodium-ion capacitors (SICs). In this work, we designed and synthesized oriented SnS nanosheets confined in graphene in the presence of poly(diallyl dimethyl ammonium chloride) by electrostatic self-assembly during hydrothermal growth. SnS nanosheets growing along (l00) and (0l0) directions are suppressed because of the confinement by graphene, which exhibit smaller thickness and particle size. These nanostructures expose abundant open edges because of the presence of Sn4+-O, which offers rich active sites and Na+ easy transport pathways. Vacancies formed at these edges along with S and N codopants in the graphitic structure synergistically promoted Na+ surface adsorption/desorption. Such nanocomposites with SnS nanosheets confined by N,S codoped graphene demonstrated significantly enhanced pseudocapacitance. The SICs delivered excellent energy densities of 113 and 54 W h kg-1 at power densities of 101 and 11 100 W kg-1, respectively, with 76% capacity retention after 2000 cycles at 1 A g-1.

6.
Small ; 15(47): e1903613, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31650696

RESUMO

The composition, crystallinity, morphology, and trap-state density of halide perovskite thin films critically depend on the nature of the precursor solution. A fundamental understanding of the liquid-to-solid transformation mechanism is thus essential to the fabrication of high-quality thin films of halide perovskite crystals for applications such as high-performance photovoltaics and is the topic of this Review. The roles of additives on the evolution of coordination complex species in the precursor solutions and the resulting effect on perovskite crystallization are presented. The influence of colloid characteristics, DMF/DMSO-free solutions and the degradation of precursor solutions on the formation of perovskite crystals are also discussed. Finally, the general formation mechanism of perovskite thin films from precursor solutions is summarized and some questions for further research are provided.

7.
ACS Appl Mater Interfaces ; 11(39): 35977-35986, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31497941

RESUMO

Layered double hydroxides (LDHs) have attracted tremendous interest for applications in energy harvest and storage. However, the aggregation of nanosheets compromises the accessible active sites and limits their electrochemical performance, especially at high rates. The present study reports the synthesis of highly dispersed NiFe-LDH nanosheets anchored on reduced graphene oxide (NiFe-LDH/rGO) composites chemically bonded via a facile one-step hydrothermal method. Defect-riched rGO provides abundant active sites for heterogeneous nucleation of NiFe-LDH nanosheets, achieving the much efficient charge transfer between rGO and NiFe-LDH as compared to physically mixed NiFe-LDH + rGO. The crystallite size can effectively reduce to 5.5 nm smaller than 15.1 nm of NiFe-LDH without rGO, beneficial to expose more active surface for fast ion diffusion and redox reactions. NiFe-LDH/rGO as an anode material in lithium-ion batteries shows superior lithium storage capacity with 1202 mAh g-1 after 100 cycles at 100 mA g-1 and high-rate performance with 543 mAh g-1 even at 2000 mA g-1. The corresponding lithium-ion capacitor with NiFe-LDH/rGO anode and mesoporous carbon microsphere cathode exhibits high energy density and power density simultaneously, with 133 Wh kg-1 at 25 W kg-1 and 4016 W kg-1 at 58 Wh kg-1, showing the great potential for high-performance hybrid energy storage systems.

8.
Biosens Bioelectron ; 142: 111594, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31430612

RESUMO

We report a novel anode electrocatalyst, iron carbide nanoparticles dispersed in porous graphitized carbon (Nano-Fe3C@PGC), which is synthesized by facile approach involving a direct pyrolysis of ferrous gluconate and a following removal of free iron, but provides microbial fuel cells with superior performances. The physical characterizations confirm the unique configuration of iron carbide nanoparticles with porous graphitized carbon. Electrochemical measurements demonstrate that the as-synthesized Nano-Fe3C@PGC exhibits an outstanding electrocatalytic activity toward the charge transfer between bacteria and anode. Equipped with Nano-Fe3C@PGC, the microbial fuel cells based on a mixed bacterium culture yields a power density of 1856 mW m-2. The resulting excellent performance is attributed to the large electrochemical active area and the high electronic conductivity that porous graphitized carbon provides and the enriched electrochemically active microorganisms and enhanced activity towards the redox reactions in microorganisms by Fe3C nanoparticles.


Assuntos
Fontes de Energia Bioelétrica , Compostos Inorgânicos de Carbono/química , Grafite/química , Compostos de Ferro/química , Nanoestruturas/química , Fontes de Energia Bioelétrica/economia , Fontes de Energia Bioelétrica/microbiologia , Compostos Inorgânicos de Carbono/economia , Catálise , Condutividade Elétrica , Eletrodos , Desenho de Equipamento , Grafite/economia , Compostos de Ferro/economia , Nanopartículas/química , Nanopartículas/economia , Nanopartículas/ultraestrutura , Nanoestruturas/economia , Nanoestruturas/ultraestrutura , Porosidade
9.
Adv Sci (Weinh) ; 6(16): 1900162, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31453056

RESUMO

The inferior tolerance with reversible accommodation of large-sized Na+ ion in electrode materials has plagued the adaptability of sodium-ion chemistry. The sluggish diffusion kinetics of Na+ also baffles the desirability. Herein, a carbon fiber supported binder-free electrode consisting of bismuth and carbon composite is designed. Well-confined bismuth nanodots are synthesized by replacing cobalt in the metal-organic frameworks (MOF)-derived, nitrogen-doped carbon arrays, which are demonstrated with remarkable reversibility during sodiation and desodiation. Cobalt species in the pristine MOF catalyze the graphitization around organic components in calcination, generating a highly conductive network in which the bismuth is to be embedded. The uniformly dispersed bismuth nanodots provide plenty boundaries and abundant active sites in the carbon arrays, where fast sodium storage kinetics are realized to contribute extra capacity and excellent rate performance.

10.
Small ; 15(31): e1901747, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31215181

RESUMO

A local electric field is induced to engineer the interface of vanadium pentoxide nanofibers (V2 O5 -NF) to manipulate the charge transport behavior and obtain high-energy and durable supercapacitors. The interface of V2 O5 -NF is modified with oxygen vacancies (Vö) in a one-step polymerization process of polyaniline (PANI). In the charge storage process, the local electric field deriving from the lopsided charge distribution around Vö will provide Coulombic forces to promote the charge transport in the resultant Vö-V2 O5 /PANI nanocable electrode. Furthermore, an ≈7 nm porous PANI coating serves as the external percolated charge transport pathway. As the charge transfer kinetics are synergistically enhanced by the dual modifications, Vö-V2 O5 /PANI-based supercapacitors exhibit an excellent specific capacitance (523 F g-1 ) as well as a long cycling lifespan (110% of capacitance remained after 20 000 cycles). This work paves an effective way to promote the charge transfer kinetics of electrode materials for next-generation energy storage systems.

11.
Small ; 15(30): e1902280, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31187934

RESUMO

High energy and efficient solar charging stations using electrochemical capacitors (ECs) are a promising portable power source for the future. In this work, two kinds of metal-organic framework (MOF) derivatives, NiO/Co3 O4 microcubes and Fe2 O3 microleaves, are prepared via thermal treatment and assembled into electrochemical capacitors, which deliver a relatively high specific energy density of 46 Wh kg-1 at 690 W kg-1 . In addition, a solar-charging power system consisting of the electrochemical capacitors and monocrystalline silicon plates is fabricated and a motor fan or 25 LEDs for 5 and 30 min, respectively, is powered. This work not only adds two novel materials to the growing categories of MOF-derived advanced materials, but also successfully achieves an efficient solar-ECs system for the first time based on all MOF derivatives, which has a certain reference for developing efficient solar-charge systems.

12.
ACS Appl Mater Interfaces ; 11(30): 26976-26984, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31251558

RESUMO

New anode materials with large capacity and long cyclability for next-generation potassium-ion batteries (PIBs) are required. PIBs are in the initial stage of investigation and only a few anode materials have been explored. In this study, for the first time, an SnP3/C nanocomposite with superior cyclability and rate performance was evaluated as an anode for PIBs. The SnP3/C nanocomposite was synthesized by a facile and cost-effective high-energy ball-milling technique. The SnP3/C electrode delivered a first reversible capacity of 410 mAh g-1 and maintained 408 mAh g-1 after 50 cycles at a specific current of 50 mA g-1. After 80 cycles at a high specific current of 500 mA g-1, a high capacity of 225 mAh g-1 remained. From a crystallographic analysis, it was suggested that the SnP3/C nanocomposite underwent a sequential and reversible conversion and alloying reactions. The excellent cycling stability and rate capability of the SnP3/C electrode were attributed to the nanosized SnP3 particles and carbon buffer layer, which supplied channels for the migration of K-ions and mitigated the stress induced by a large volume change during potassiation/depotassiation. In addition, a full cell composed of the SnP3/C nanocomposite anode and potassium Prussian blue cathode exhibited a reversible capacity of 305 mAh g-1 at a specific current of 30 mA g-1 and retained 71.7% of the original capacity after 30 cycles. These results are important for understanding the electrochemical process of the SnP3/C nanocomposite and using the SnP3/C as an anode for PIBs.

13.
Nanoscale ; 11(19): 9626-9632, 2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31065662

RESUMO

The usefulness of self-powered quantum dot (QD) photodetectors is increased if they are fabricated on flexible substrates. However, the performance of such photodetectors is typically significantly worse than similar devices fabricated on glass substrates due to poor charge transport performance. Here, a novel flexible self-powered CdSexTe1-x QD photodetector with a double hole transport layer of PEDOT:PSS/P-TPD has been fabricated, which achieves a performance comparable to that of rigid devices. The energy level of the P-TPD layer matches well with that of the PEDOT:PSS and QD layers, which significantly enhances photodetection capability across a spectral region that spans the ultraviolet, visible and near infrared (UV-NIR). A low dark current density (1.03 × 10-6 mA cm-2) and a large specific detectivity of approximately 2.6 × 1012 Jones at a wavelength of 450 nm are demonstrated, significantly outperforming previously reported flexible QD-based detectors. This improvement in performance is attributed to both increased hole transport efficiency and the inhibition of electron transport from the QDs into the PEDOT:PSS layer. The photodetector also exhibits good sensitivity under weak illumination, producing a photocurrent of 196 × 10-6 mA cm-2 under an irradiance of 5 µW cm-2. Moreover, no significant performance degradation is observed after 150 bending cycles to an angle of 60 degrees.

14.
ACS Appl Mater Interfaces ; 11(17): 15573-15580, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30965001

RESUMO

A high-performance, low-cost, aqueous Al-ion supercapacitor was fabricated based on nanostructured V2O5 impregnated mesoporous carbon microspheres (MCM/V2O5) electrodes and Al2(SO4)3 electrolyte for efficient energy storage. MCM/V2O5 composites exhibit high dispersion of nanostructured V2O5 in a mesoporous carbon matrix, beneficial to fast reversible redox reactions with a short diffusion path. The corresponding capacitor illustrates the distinguishable redox behavior, most likely due to the Al3+ intercalation/deintercalation leading to the reduction/oxidation of V5+/V4+. It delivers a high-energy density of 18.0 Wh kg-1 at 147 W kg-1 and a long cycling lifespan with over 88% capacitance retention over 10 000 cycles. The competitive performance can be ascribed to the integration of the electric double layer capacitance provided from MCM with pseudocapacitance contributed by nanostructured V2O5. This work offers the possibilities of high-performance aqueous capacitors based on trivalent Al-ion as guest species, providing new directions for future development of supercapacitors.

15.
ACS Appl Mater Interfaces ; 11(18): 16647-16655, 2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-30977632

RESUMO

Oxygen vacancies (Vö) play a crucial role in energy storage materials. Oxygen-vacancy-enriched vanadium pentoxide/poly(3,4-ethylenedioxythiophene) (Vö-V2O5/PEDOT) nanocables were prepared through the one-pot oxidative polymerization of PEDOT. PEDOT is used to create tunable concentrations of Vö in the surface layer of V2O5, which has been confirmed by X-ray absorption near edge structure (XANES) analysis and X-ray photoelectron spectroscopy (XPS) measurements. Applied as electrode materials for supercapacitors, the electrochemical performance of Vö-V2O5/PEDOT is improved by the synergistic effects of Vö in V2O5 cores and PEDOT shells with rapid charge transfer and fast Na+ ion diffusion; however, it is compromised subsequently by excessive Vö in consuming more V5+ cations for Faradic reactions. Consequently, the specific capacitance and the energy density of Vö-V2O5/PEDOT nanocables are significantly enhanced when the overall concentration of Vö is 1.3%. The migration of Vö renders an increased capacitance (105% retention) after 10 000 cycles, which is verified and corroborated with density functional theory simulations and XANES analysis. This work provides an illumination for the fabrication of high-performance electrode materials in the energy storage field through Vö.

16.
Small ; 15(10): e1804740, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30714304

RESUMO

Developing low cost, long life, and high capacity rechargeable batteries is a critical factor towards developing next-generation energy storage devices for practical applications. Therefore, a simple method to prepare graphene-coated FeS2 embedded in carbon nanofibers is employed; the double protection from graphene coating and carbon fibers ensures high reversibility of FeS2 during sodiation/desodiation and improved conductivity, resulting in high rate capacity and long-term life for Na+ (305.5 mAh g-1 at 3 A g-1 after 2450 cycles) and K+ (120 mAh g-1 at 1 A g-1 after 680 cycles) storage at room temperature. Benefitting from the enhanced conductivity and protection on graphene-encapsulated FeS2 nanoparticles, the composites exhibit excellent electrochemical performance under low temperature (0 and -20 °C), and temperature tolerance with stable capacity as sodium-ion half-cells. The Na-ion full-cells based on the above composites and Na3 V2 (PO4 )3 can afford reversible capacity of 95 mAh g-1 at room temperature. Furthermore, the full-cells deliver promising discharge capacity (50 mAh g-1 at 0 °C, 43 mAh g-1 at -20 °C) and high energy density at low temperatures. Density functional theory calculations imply that graphene coating can effectively decrease the Na+ diffusion barrier between FeS2 and graphene heterointerface and promote the reversibility of Na+ storage in FeS2 , resulting in advanced Na+ storage properties.

17.
Adv Mater ; 31(6): e1804204, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30556176

RESUMO

The charge transport system in an energy storage device (ESD) fundamentally controls the electrochemical performance and device safety. As the skeleton of the charge transport system, the "traffic" networks connecting the active materials are primary structural factors controlling the transport of ions/electrons. However, with the development of ESDs, it becomes very critical but challenging to build traffic networks with rational structures and mechanical robustness, which can support high energy density, fast charging and discharging capability, cycle stability, safety, and even device flexibility. This is especially true for ESDs with high-capacity active materials (e.g., sulfur and silicon), which show notable volume change during cycling. Therefore, there is an urgent need for cost-effective strategies to realize robust transport networks, and an in-depth understanding of the roles of their structures and properties in device performance. To address this urgent need, the primary strategies reported recently are summarized here into three categories according to their controllability over ion-transport networks, electron-transport networks, or both of them. More specifically, the significant studies on active materials, binders, electrode designs based on various templates, pore additives, etc., are introduced accordingly. Finally, significant challenges and opportunities for building robust charge transport system in next-generation energy storage devices are discussed.

18.
Sci Rep ; 8(1): 17389, 2018 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-30478382

RESUMO

Ferroelectric functionalized dye-sensitized solar cells were fabricated by using a positively-poled LiNbO3 substrate coated with ITO (ITO-LiNbO3) as a collector electrode and demonstrated enhanced power conversion efficiency. Surface potential properties of TiO2 nanoparticle film coated on the ITO-LiNbO3 (TiO2/ITO-LiNbO3) examined by Kelvin probe force microscopy (KPFM) confirmed that a large electric field (a few 10 V/µm) generated from LiNbO3 can penetrate through the ITO layer and is applied to TiO2 film. This polarization-induced electric field leads to an increased photocurrent density by attracting and promoting electrons to direct transport through the mesoporous TiO2 network toward the collector electrode and a decreased charge recombination by facilitating electrons to pass through fewer boundaries of nanoparticles, resulting in high power conversion efficiency. The power conversion efficiency was enhanced by more than 40% in comparison with that without polarization-induced electric field. Incorporating functional ferroelectrics into photovoltaic cells would be a good strategy in improving photovoltaic performance and is applicable to other types of photovoltaic devices, such as perovskite solar cells.

19.
Chem Commun (Camb) ; 54(89): 12598-12601, 2018 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-30346452

RESUMO

A facile in situ seeded ion exchange approach was used to produce nearly monodisperse and uniformly distributed PbS quantum dots (QDs) on mesoporous TiO2 films. This strategy solves the size distribution problem for conventional SILAR-processed QDs and shows promise for constructing high-performance near-infrared-responsive PbS QD solar cells.

20.
ACS Appl Mater Interfaces ; 10(43): 37005-37013, 2018 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-30298722

RESUMO

On account of the low-temperature solution fabrication, the much high defect density at the interfaces and grain boundaries of halide perovskite films is recognized as one of the big obstacles toward high-efficiency solar cells. Here, the time-resolved photoluminescence (TRPL) with incident light exciting from the upper surface and bottom of halide perovskite films, respectively, showed very different results, verifying the much more surface trap states in the film. To eliminate the defects and enhance the photovoltaic properties of perovskite solar cells (PSCs), we designed a facile and effective method to repair the defects of the perovskite film using formamidinium iodine (FAI) solution. The dissociative FA+ and I- ions could compensate for the loss of volatile organic cations and also fill the I- vacancies of halide perovskites. After repairing defects with proper concentration of FAI solution, the TRPL curves obtained by light exciting from the different sides of the perovskite film nearly overlap together, indicating the reduction of surface traps. As a result, both the total carrier lifetime and charge extractions were improved by removing the nonradiative channels (surface traps), which universally enhanced the power conversion efficiency and stability of the planar heterojunction structural PSCs.

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