bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atomic Layer 2D MoS2 Coated Li-Metal for Advanced Li-Metal Rechargeable Batteries
Authors: Choi Wonbong 
Published: February 2020

Rapidly increasing markets for electric vehicles (EVs), energy storage for backup support systems and high-power portable electronics demand batteries with higher energy density, higher power density, and longer cycle life. The success of Li-S cells depends in large part to the utilization of metallic lithium as anode material. Metallic lithium, however, is prone to grow parasitic dendrites and is highly reactive to several electrolytes; it is also susceptible to polysulfides when used in Li-S cells. Here, we show that a ~10 nm thick 2D MoS2 can act as a protective layer for Li-metal anodes, greatly improving the performances of Li-S batteries [2, 3]. In particular, we observe stable Li electrodeposition and the suppression of dendrite nucleation sites. The deposition and dissolution process of a symmetric MoS2 coated Li-metal cell operates at a current density of 10 mA cm-2 with low voltage hysteresis, and a three-fold improvement in cycle-life than using bare Li-metal. In a Li-S full cell configuration, using the MoS2 coated Li as anode and a 3D carbon nanotube-sulfur cathode, we obtain a specific energy density of ~600 Wh kg-1 and a Coulombic efficiency of ~98% for over 1200 cycles at 0.5 C. Our approach can lead to the realization of high energy density and safe Li-metal based rechargeable batteries.
Figure. Long-term cycling performance of Li–S battery with the MoS2-coated Li anode measured at 0.5 C for 1,200 cycles [3]

References:

High performance rechargeable Li-S batteries using binder-free large sulfur-loaded three- dimensional carbon nanotubes, M Patel, E Cha, C Kang, B Gwalani, W Choi, Carbon http://dx.doi.org/10.1016/j (2017)

Recent development of 2D materials and their applications, Wonbong Choi, Nitin Choudhary, Juhong Park, Deji Akinwande, Younghee Lee, Materials Today, 116-130, 20, (2017).

2D MoS2 as an efficient protective layer for lithium metal anodes in high performance Li-S batteries, Cha, E., Patel, M.D., Park, J., Hwang, J., Prasad, V., Cho, K., and Choi, W., Nature Nanotechnology, 13, pages337–344 (2018).

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In-Situ Growth of Conductive Copper Metal Organic Framework on Silicon Nanoparticles for High Performance Lithium Ion Batteries
Authors: Nazir Aqsa , Park Chan-Jin 
Published: February 2020

The race in developing rechargeable lithium ion batteries (LIBs) with higher capacity and longer cycle life is getting severer. Currently, LIBs are the ideal choice as power source ranging from portable electronic devices to electric vehicles (EVs) and implantable medical devices. However, conventional LIBs are not enough to satisfy the consumer’s demands due to the inherent capacity restriction of conventional electrode materials such as graphite. Si, which can form alloys with Li at low electrode potential, has ability to substitute the carbon based anodes due to its high theoretical specific capacity (4200 mAh g−1, almost 10 times higher than the commercial carbon anode), natural abundance (27.7%, Si is the second most abundant element in earth) and environmental friendliness. However, the cyclability and capacity of bare Si based electrodes are still insufficient. In actual, poor Li diffusivity, intrinsic low electrical conductivity, and large volume variation (>400%) during alloying have restricted the practical application of Si based electrodes. Thus far, to address all these issues, scientists have focused on making Si nanostructures (nanowires, nanorods, nanotubes, and nanoparticles) and using carbon s. Nevertheless, for Si anode, to prevent the capacity fading and maintain longer cycle life to the level comparable to that of graphite, a breakthrough is needed.
In the present work, we introduce in-situ growth of novel two dimensional conducting copper metal organic framework (MOF) on Si nanoparticles for high power density and longer cycle life. The Cu MOF exhibited two dimensional network structure around the Si nanoparticles. Although carbon offers low capacity, its presence around the Si nanoparticles in MOF form can function as a mechanical support against volume expansion and may provide an effective electron conducting route. In this way, MOF coated Si electrode could show structural stability. Furthermore, the porous carbon framework of MOF with evenly distributed Cu metal cores was also advantageous for improving conductivity and Li storage of Si anode. A full cell composed of MOF coated Si anode and LiCoO2 cathode with better cycle life and rate capability is also demonstrated.
The Reaction between Metal Disulfides Interlayer and Polysulfides in Lithium-Sulfur Batteries
Authors: Paolella Andrea , Zaghib Karim 
Published: February 2020

Many scientists think that in Li-S batteries polysulfides have catalytic[1-2] reactions when are in contact with heterogeneous separators. In our work[3], we investigated the reactivity of layered metal disulfides MS2 (M=W,Mo) as interlayer in a Li–S battery and observed a reduction chemical reaction involving the removal of metal ions by polysulfides after a chemical (and not catalytic) reaction. Interestingly we observed the formation of metallic tungsten nanoparticles (confirmed by ex situ Transmission Electron Microscopy characterization) in the sulfur cathode is the result of tungsten ion oxidation reaction and their subsequent recrystallization during discharge. In situ Raman spectroscopy technique shows i) the efficacy of WS2 separator to filter and suppress polysulfides at lithium metal side (and then shuttle reaction) and ii) the polysulfides species involved in heterogeneous chemical reaction between interlay WS2 and polysulfides.
References

Thangavel, N. K., Gopalakrishnan, D., Mohana, L. & Arava, R. Understanding Heterogeneous Electrocatalysis of Lithium Polysulfide Redox on Pt and WS 2 Surfaces. J. Phys. Chem. C 121, 12718–12725 (2017).

Lei, T. et al. Multi-Functional Layered WS 2 Nanosheets for Enhancing the Performance of Lithium – Sulfur Batteries. Adv. Energy Mater. 1601843 (2016). doi:10.1002/aenm.201601843

Paolella, A. et al. The Role of Metal Disulfide Interlayer in Li − S Batteries. J. Phys. Chem. C 122, 1014–1023 (2018).
(Invited) Controlling Nanotube-Nanotube Interactions in Carbon Nanotube Networks: Implications for Energy Transport and Harvesting
Authors: Ferguson Andrew John , Blackburn Jeffrey L. 
Published: February 2020

While the unique chemical and physical structure of semiconducting single-walled carbon nanotubes (s-SWCNTs) were identified decades ago, marking these nanoscale materials as promising candidates for constituents in a variety of optical and electronic applications, the ability to generate high-purity samples has hampered efforts to validate these expectations. The intervening years have played witness to a number of elegant enrichment strategies aimed at extracting tailored semiconducting SWCNT species from the raw soot, from the use of subtly tunable surfactant interactions to the exploitation of specific DNA sequences. In contrast, we employ an enrichment approach based on conjugated polymers, typically derived from the fluorene moiety, since they show great promise with regards to their high selectivity and viability for scalable manufacturing approaches.
As alluded to above, these fluorene-based (co-)polymers confer solubility on the s-SWCNT species, allowing for the preparation of highly enriched s-SWCNT dispersions that can be deposited using a variety of solution-processing approaches. Unfortunately, the strong van de Waals forces between the π-electron systems of the polymer and SWCNT that enable the selective extraction of semiconducting SWCNTs with high purity also make removal of the polymer difficult. Since these polymers typically have a wide bandgap they can act as an insulating coating on the surface of the individual SWCNTs within functional networks, inhibiting the transport of energy in the form of excitons and/or charge carriers.
Here we demonstrate approaches that allow us to replace the strongly-bound polymers with derivatives that can be removed using simple solution-based chemical strategies, resulting in networks with modified energy transport properties. We show that removal of the polymer results in a significant enhancement of the charge carrier mobility and electrical conductivity in doped s-SWCNT networks. Finally, we extend the approach to samples strongly enriched in a single chiral s-SWCNT species, which allows us to employ transient spectroscopic techniques to probe exciton transport within the s-SWCNT network with high spectral fidelity. We show that the efficiency of exciton transport is subtly dependent on the complex interplay between polymer removal and carbon nanotube bundling. Our studies highlight a methodology by which high-performance s-SWCNT thin films can be prepared and discuss the implications of our findings on the potential to realize their promise for electronic and optoelectronic applications.
Synthesis of Co-Fe Alloy 1D Nanocone Array Electrodes with Aluminum Oxide Template for Water Spliting Reaction.
Authors: Skibinska Katarzyna , Kutyla Dawid , Kolczyk Karolina , Kowalik Remigiusz , Zabinski Piotr 
Published: February 2020

Nanostructured materials have an enormous application potential because of their novel physical and chemical properties which appear upon reduction of the length scales toward a few nanometer. Among the nano-structured materials, nano-cone arrays have received particular attention in the last years. Due to their specific structure and properties, nano-cones are attractive for very different applications. Producing and designing proper nano-crystalline structures could further improve the catalytic properties and replace expensive precious metals (platinum). Hence, the fabrication of Co alloy nano-cones opens the window to promising applications in the field of electrocatalysis
Porous anodic aluminum oxide (AAO) is a popular template for synthesis of ordered arrays of nanostructured materials. By the controlling of anodization conditions or applying an appropriate post-anodization treatment the internal pore structure can be changed. Conical pores can be obtained basing on alternating repetition of the anodization and pore widening process during fabrication of AAO. To obtain free standing metallic nanocones the Al2O3 template was chemically etched in dilute phosphoric acid solution.
In this case the process of cobalt electrodeposition was carried out in a two-electrode cell. The working electrode was AAO sample, the anode was a platinum plate. Influence of temperature and H3PO4 and H2SO4 solutions in the first step of anodization was examined. An attempt was made to synthesize Co based alloy nanocones.
Acknowledgement
This work was financially supported by Polish National Science Center (NCN) under grant UMO-2016/23/G/ST5/04058. The authors would like to acknowledge the COST MP1407 Action for networking.
Mechanistic Investigation with Kinetic Parameters on Water Oxidationcatalyzed By Manganese Oxide Nanoparticle Film
Authors: Seo Hongmin , Jin Kyoungsuk , Park Sunghak , Cho Kang Hee , Lee Kang-Gyu , Nguyen Đăng Thành , Lee Jong-Sook , Nam Ki Tae 
Published: February 2020

Water electrolysis has been regarded an attractive approach to produce sustainable energy without undesirable byproducts. The anodic half reaction, oxygen evolving reaction (OER), is a major bottleneck for overall water electrolysis process because of its complex four electron transfer steps and high activation energy for O-O bond formation. Thus, transition-metal-based film-type electrocatalysts have been extensively reported with moderate efficiency due to their low price and abundance. Interestingly, transition metal based OER catalyst film generally exhibited optimal catalytic performance at considerable thickness (~ hundreds nanometers). The overall catalytic performance for the film-type catalysts are determined by various electrochemical processes, such as surface catalysis and electron transport. Therefore, to establish rational design rule for efficient OER electrocatalyst, it is necessary to extract well-defined kinetic parameters describing each electrochemical processes. In this regard, electrochemical impedance spectroscopy (EIS) is effective analysis to decouple and parametrize complicated electrochemical behavior in the catalyst film during OER.
Here, we conducted EIS analysis for sub 10 nm-sized partially oxidized MnO nanoparticles (Mn-oxide NPs) operating with superb activity under neutral condition. Furthermore, we proposed a transmission line model with Havriliak-Negami capacitors to obtain reliable kinetic parameters for OER on the Mn-oxide NPs film. From this analysis, we explained the rationale for the optimum thickness. Also, we revealed that protons are involved in transport on the surface of p-MnO NPs, which directly proved the ongoing hypothesis of the oxo-hopping mechanism during catalysis. Furthermore, from correlation between the reaction rate constant (22.1 s-1 at 1.35 V vs. NHE) and TOF values, only small ratio of Mn sites served as factual active sites for OER. We believe that this mechanistic investigation using EIS analysis with our circuit model could be an effective platform to investigate comprehensive electrochemical processes in general film-type electrocatalysts.

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Preparation of Sb-Doped SnO2 Nanoparticle with High Surface Area for Use As a Stable Anode Catalyst Support for PEM Electrolyzers.
Authors: Zhou Xiangyang , Li Bing , Yang Daijun , Lv Hong , Zhang Cunman 
Published: February 2020

Proton exchange membrane (PEM) water electrolysis has been considered as one of the most promising technologies for large H2 production. While the cost and stability of PEM are the main obstacles for the commercial application. Here we report a cost-effective catalyst, which consists of IrO2 nanoparticles supported on Sb-doped SnO2 (ATO). ATO support is synthesized by using templating process and hydrothermal method to improve its thermal stability. It has a mesoporous structure, small particle size, and high surface area. After loading IrO2 via Adams fusion method, the IrO2/ATO catalyst shows high electrochemical stability, according to repetitive potential cycling. This catalyst also shows a good electrochemical performance in single cell.
Firstly, we prepared a series of ATO samples and named them as the Brunauer Emmett Teller model (BET) surface area. The surface area and pore size distribution of the obtained ATO samples were calculated by BET and nonlocal density functional theory (NLDFT). As shown in Fig.1a, the pore size become smaller with the increases of BET surface area, and the high surface area may be contributed to high synthesize temperature and long synthesize time. Secondly, we use the as-prepared ATO samples as catalysts support for IrO2, the catalysts named as BET surface area-IrO2 (e.g. 107-IrO2) and the IrO2 loading is 40 wt%. Fig.1b shows the cyclic voltammetry (CV) performance of different catalysts, it is quite clear that when supported by ATO, the voltammograms of these supported catalysts are dissimilar in shape from that of unsupported IrO2. The electrochemically active surface area (ECSA) of 170-IrO2 is obvious higher than the other ATO supported catalyst and a little higher than pure IrO2. This indicate that the 170 sample has the appropriate surface area as well as pore size distribution and it is best used as for IrO2 catalyst support. Finally, the accelerated degradation testing (ADT) was performed to investigated the durability of the 170-IrO2 catalyst in rotating disk electrode (RDE) test. As shown in Fig.1c the CV curves almost overlap before and after 9000 cycles’ ADT. Fig.1d shows the Linear sweep voltammetry (LSV) results of the catalyst samples before and after ADT. It is quite obvious that the 170-IrO2 catalyst is maintained stable with only a little loss in the catalytic activity.
We have successfully made a series of ATO through templating process followed by hydrothermal method with different BET surface area and used as catalyst support for IrO2. The 170-IrO2 catalyst demonstrates high electrochemical performance and good stability. Herein, the as-synthesized ATO is considered to be a promising oxygen evolution catalyst support for solid polymer electrolyte water electrolyzer applications.

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MOF-Derived Alloy Nanoparticles for Highly Durable Fuel Cell Electrocatalysts
Authors: Yoo Ji Mun , Chung Dong Young , Ahn Chi-Yeong , Sung Yung-Eun 
Published: February 2020

Tailoring material properties of electrode is of great importance because both high activity and durability are required for oxygen reduction electrocatalysts in a fuel cell. However, effective strategy for rational material design should be developed to guarantee stable long-term operation of active electrocatalysts, which unfortunately has been overlooked often.
Here, we report an effective strategy of utilizing metal-organic framework (MOF) as precursor for multimetallic alloy nanocrystals. Due to its coordinated metal and N-containing organic molecules, MOF is a highly desirable material to make nanocrystals hybridized with N-doped carbon via simple heat treatment. With delicate selection of composition and controlled heat treatment condition, highly durable and active alloy nanoparticles were successfully derived and showed excellent electrochemical stability in oxygen reduction reaction. This strategy was also extended to other electrocatalysis too, where alloy nanocrystals coated in the N-doped carbon layers shows excellent durability for long term operation. Through this study, we highlight the rational design for highly durable and active electrocatalysts.
(Invited) Bioinspired Water Oxidation Electrocatalysts Based on Manganese Oxide
Authors: Nam Ki Tae 
Published: February 2020

Water splitting is regarded as a promising step towards environmentally sustainable energy schemes. The oxygen evolution reaction (OER) requires extremely high overpotential due to its slow reaction kinetics. The water oxidizing cluster in photosystem II, in the form of cubical Mn4CaO5 cluster, efficiently catalyzes water oxidation. Inspired by Mn4CaO5 cluster, we previously identified a new crystal structure, Mn3(PO4)2-3H2O, and demonstrated its superior catalytic performance at neutral pH. We revealed that structural flexibility can stabilize Jahn-Teller distorted Mn(III), and thus facilitate Mn redox during catalysis. Additionally, we verified influence of Mn valency and asymmetric geometry on water oxidation catalysis using Li2MnP2O7and its derivatives.
Next, we translate the underlying principles in Mn4CaO5 cluster into synthetic heterogeneous catalysts. Sub-10 nm-sized monodispersed partially oxidized manganese oxide nanoparticles were shown to exhibit not only superior catalytic performance for oxygen evolution, but also unique electrokinetics, as compared to their bulk counterparts. In the present work, the water-oxidizing mechanism of partially oxidized MnO nanoparticles was investigated using integrated in situ spectroscopic and electrokinetic analyses. We successfully demonstrated that, in contrast to previously reported manganese (Mn)-based catalysts, Mn(III) species are stably generated on the surface of MnO nanoparticles via a proton-coupled electron transfer pathway. Furthermore, we confirmed as to MnO nanoparticles that the one-electron oxidation step from Mn(II) to Mn(III) is no longer the rate-determining step for water oxidation and that Mn(IV)═O species are generated as reaction intermediates during catalysis.
Conformal and Continuous Deposition of Bifunctional Cobalt Phosphide Layers on p-Silicon Photocathodes for Improved Solar Hydrogen Evolution
Authors: Liu Lifeng , Thalluri Sitaramanjaneva Mouli 
Published: February 2020

p-Silicon (Si) has been extensively investigated in recent years as a promising photocathode for solar-driven hydrogen evolution. However, it remains challenging to fabricate Si photocathodes having both high photoelectrocatalytic activity and long-term operational stability through a simple and affordable approach. Herein, we report conformal and continuous deposition of a di-cobalt phosphide (Co2P) layer on lithography-patterned highly-ordered Si nanowire (SiNW) arrays via a cost-effective drop-casting method followed by a low-temperature phosphorization treatment [1]. The as-deposited Co2P layer consists of crystalline nanoparticles and has an intimate contact with SiNWs, forming a well-defined SiNW@Co2P core/shell nanostructure. The conformal and continuous Co2P layer endows dual functions: on the one hand, it serves as a highly-efficient catalyst capable of substantially improving the photoelectrocatalytic activity towards the hydrogen evolution reaction (HER); on the other hand, it can effectively passivate SiNWs to protect them from photo-oxidation, thus prolonging the lifetime of the electrode. As a consequence, when used for solar-driven hydrogen evolution, the SiNW@Co2P photocathode with an optimized Co2P layer thickness exhibits a high photocurrent density of -21.9 mA cm-2 at 0 V versus reversible hydrogen electrode (RHE) and excellent operational stability of up to 20 hours, outperforming many nanostructured silicon photocathodes reported in the literature. Furthermore, we fabricate inverted pyramid textured Si (SiIP) photocathodes coated with a conformal and continuous layer of Co2P [2], which show a photocurrent density as high as -35 mA cm-2 and can constantly split water up to 150 hours without obvious degradation. The combination of passivation and catalytic functions in a single continuous layer represents a promising strategy for designing high-performance semiconductor photoelectrodes for use in solar-driven water splitting, which may simplify the fabrication procedures and potentially reduce the production cost.

Acknowledgement

This work was funded by ERDF funds through the Portuguese Operational Programme for Competitiveness and Internationalization COMPETE 2020, and national funds through FCT – The Portuguese Foundation for Science and Technology, under the project “PTDC/CTM-ENE/2349/2014” (Grant Agreement No. 016660). The work is also partially funded by the Portugal-China Bilateral Collaborative Programme (FCT/21102/28/12/2016/S).

References:

[1] S. M. Thalluri, J. Borme, K. Yu, J. Y. Xu, I. Amorim, J. Gaspar, L. Qiao, P. Ferreira, P. Alpuim, L. Liu, Nano Res. 11 (2018) 4823.
[2] S. M. Thalluri, B. Wei, R. Thomas, L. Qiao, Z. C. Wang, L. Liu, Small submitted.