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2022年8月嘲风作品集（二）

已有 1067 次阅读 2022-11-29 16:29 |个人分类:作品发表|系统分类:论文交流

▲ Vol 36 Issue 15 | August 04, 2022

Enhancing Electrochemical Performance of CoF2–Li Batteries via Honeycombed Nanocomposite Cathode

Yujie Wang, Mingyu Zhang, Yuxuan Zhang, Yafeng Wang, Wenxin Liu, Chujie Yang, Veniamin Kondratiev, and Feixiang Wu

Metal fluoride–lithium batteries have been viewed as very promising candidates for next-generation rechargeable batteries with higher energy densities. However, the intrinsic insulating properties of metal fluoride cathode lead to the poor reaction kinetics and unsatisfactory electrochemical performance. Herein, a honeycombed CoF2@C nanocomposite with a high specific surface area up to 180.4 m2 g–1, in which the nanosized CoF2 particles with size of 5–25 nm are evenly embedded in the honeycombed carbon framework, is prepared by the low-temperature fluorination of honeycombed Co@C nanocomposite precursor. As expected, the as-produced CoF2@C nanocomposite can deliver a high-capacity utilization of 365 mAh g–1 and an average capacity retention of 81.9% over 300 cycles at a current density of 110 mA g–1, as well as a reasonable capacity of 205 mAh g–1 at 1100 mA g–1. Such excellent electrochemical performance is due to the unique configuration that achieves the nanoconfinement of conversion reaction in the metal fluoride cathode. To be specific, on the one hand, the honeycombed structure provides uniformly isolated nanospace to inhibit the volume expansion and product agglomeration in the conversion reaction. On the other hand, the excellent reaction kinetics is attributed to the three-dimensional electron and ion conduction pathway, that is, the electrons are conducted through the honeycombed carbon walls, while Li+ are transferred via the interconnected honeycomb channels, facilitating the high-capacity utilization.

https://pubs.acs.org/doi/10.1021/acs.energyfuels.2c01309

▲ Vol 144 Issue 32 | August 17, 2022

Regulating Lithium Salt to Inhibit Surface Gelation on an Electrocatalyst for High-Energy-Density Lithium–Sulfur Batteries

Xi-Yao Li, Shuai Feng, Chang-Xin Zhao, Qian Cheng, Zi-Xian Chen, Shu-Yu Sun, Xiang Chen, Xue-Qiang Zhang, Bo-Quan Li, Jia-Qi Huang, and Qiang Zhang

Lithium–sulfur (Li–S) batteries have great potential as high-energy-density energy storage devices. Electrocatalysts are widely adopted to accelerate the cathodic sulfur redox kinetics. The interactions among the electrocatalysts, solvents, and lithium salts significantly determine the actual performance of working Li–S batteries. Herein, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), a commonly used lithium salt, is identified to aggravate surface gelation on the MoS2 electrocatalyst. In detail, the trifluoromethanesulfonyl group in LiTFSI interacts with the Lewis acidic sites on the MoS2 electrocatalyst to generate an electron-deficient center. The electron-deficient center with high Lewis acidity triggers cationic polymerization of the 1,3-dioxolane solvent and generates a surface gel layer that reduces the electrocatalytic activity. To address the above issue, Lewis basic salt lithium iodide (LiI) is introduced to block the interaction between LiTFSI and MoS2 and inhibit the surface gelation. Consequently, the Li–S batteries with the MoS2 electrocatalyst and the LiI additive realize an ultrahigh actual energy density of 416 W h kg–1 at the pouch cell level. This work affords an effective lithium salt to boost the electrocatalytic activity in practical working Li–S batteries and deepens the fundamental understanding of the interactions among electrocatalysts, solvents, and salts in energy storage systems.

https://pubs.acs.org/doi/10.1021/jacs.2c04176

▲ Vol 02 Issue 08 | August 22, 2022

Suppressing the Excitonic Effect in Covalent Organic Frameworks for Metal-Free Hydrogen Generation

Hongde Yu and Dong Wang

Photocatalytic hydrogen generation is a promising solution for renewable energy production and plays a role in achieving carbon neutrality. Covalent organic frameworks (COFs) with highly designable backbones and inherent pores have emerged as novel photocatalysts, yet the strong excitonic effect in COFs can impede the promotion of energy conversion efficiency. Here, we propose a facile approach to suppress the excitonic effect in COFs, which is by narrowing the band gap and increasing the dielectric screening via a rational backbone design and chemical modifications. Based on the GW-BSE method, we uncover a linear relationship between the electronic dielectric constant and the inverse square of the optical band gap of COFs of the Lieb lattice. We further demonstrate that both reduced exciton binding energy and enhanced sunlight absorption can be simultaneously realized in COFs with a narrow band gap. Specifically, we show that one of our designed COFs whose exciton binding energy is nearly half that of g-C3N4 is capable of metal-free hydrogen production under near-infrared light irradiation. Our results showcase an effective method to suppress the excitonic effect in COFs and also pave the way for their applications in photocatalytic, photovoltaic, and other related solar energy conversions.

https://pubs.acs.org/doi/10.1021/jacsau.2c00169

▲ Vol 10 Issue 33 | August 22, 2022

Surfactant-Modified Silica Nanoparticles-Stabilized Magnetic Polydimethylsiloxane-in-Water Pickering Emulsions for Lubrication and Anticorrosion

Siwei Chen, Jinyu Wang, Hongsheng Lu, and Lu Xu

Traditional industrial lubricating emulsions usually contain a variety of constituents to fulfill their functional requirements in long-term stability, lubrication, and anticorrosion. The complexity of the constituents may produce difficulties for their preparation, storage, and recycling. To address this issue, here we design and prepare simple-component, switchable, and multifunctional Pickering emulsions using the green lubricating base oil polydimethylsiloxane, water, and silica nanoparticles modified with a series of magnetic surfactants (CnH2n+1N+(CH3)3[XCl3Br]−, n = 12, 14, and 16, X = Ce, Fe, and Gd) as compositions. The Pickering emulsions are demonstrated to be highly stable, lubricative, and anticorrosive. Their magneto-responsiveness indicates a potential application as smart lubricants. Their reversible emulsification and demulsification, which allows an effective recycling and reuse of the composite nanoparticles, can be regulated by alternative centrifugation and homogenization or successive addition of the anionic surfactant sodium dodecyl sulfate and the magnetic cationic surfactants. Both their stability and lubricity can be optimized by using surfactant C16H33N+(CH3)3[CeCl3Br]− (CTACe) as the surface coating for the silica particles. The deposition of CTACe-modified silica nanoparticles endows a metallic material with a high resistance to abrasion and corrosion. We envision that such emulsions, consisting of eco-friendly, biocompatible, and low-cost materials, could find extensive applications in sustainable chemistry and engineering.

https://pubs.acs.org/doi/10.1021/acssuschemeng.2c01753

▲ Vol 04 Issue 08 | August 23, 2022

Ultralow-Supersaturation Al Pretreatment toward Low Dislocation Density and Low Radio Frequency Loss GaN/AlN Epi-Stacks on High-Resistivity Si Substrates

Zidong Cai, Xuelin Yang, Cheng Ma, Zhenghao Chen, Danshuo Liu, Liwen Sang, Fujun Xu, Xinqiang Wang, Weikun Ge, and Bo Shen

An ultralow-supersaturation Al pretreatment approach has been proposed to achieve low threading dislocation (TD) density and low radio frequency (RF) loss GaN/AlN layer stacks on Si substrates. By employing this approach, the Al–Si liquid alloy is eliminated, and a sharp AlN/Si interface is obtained. In addition, the size of the AlN nucleation islands is enlarged and thus the TDs generated from the coalescence of the islands are reduced even at a low growth temperature. Owing to the low TD density AlN layer, a 1.5 μm crack-free GaN layer can be achieved directly on this AlN layer and no transition layers are required. The full width at half maximum values are as low as 390 and 440 arcsec for the GaN (002) and (102) diffractions, respectively. Owing to a low growth temperature and short growth time, the RF loss of the epi-stack is as low as 0.29 dB/mm at 10 GHz. This work shows great potential for the fabrication of high-quality and low-loss GaN-on-Si RF devices.

https://pubs.acs.org/doi/10.1021/acsaelm.2c00747

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