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Atomistic understanding of interfacial processing mechanism of silicon in water environment: A ReaxFF

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 570-579 doi: 10.1007/s11465-021-0642-6

摘要： The interfacial wear between silicon and amorphous silica in water environment is critical in numerous applications. However, the understanding regarding the micro dynamic process is still unclear due to the limitations of apparatus. Herein, reactive force field simulations are utilized to study the interfacial process between silicon and amorphous silica in water environment, exploring the removal and damage mechanism caused by pressure, velocity, and humidity. Moreover, the reasons for high removal rate under high pressure and high velocity are elucidated from an atomic perspective. Simulation results show that the substrate is highly passivated under high humidity, and the passivation layer could alleviate the contact between the abrasive and the substrate, thus reducing the damage and wear. In addition to more Si-O-Si bridge bonds formed between the abrasive and the substrate, new removal pathways such as multibridge bonds and chain removal appear under high pressure, which cause higher removal rate and severer damage. At a higher velocity, the abrasive can induce extended tribochemical reactions and form more interfacial Si-O-Si bridge bonds, hence increasing removal rate. These results reveal the internal cause of the discrepancy in damage and removal rate under different conditions from an atomic level.

关键词： silicon     ReaxFF     molecular dynamics     friction     damage    

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Development, applications and challenges of ReaxFF reactive force field in molecular simulations

You Han, Dandan Jiang, Jinli Zhang, Wei Li, Zhongxue Gan, Junjie Gu

《化学科学与工程前沿（英文）》 2016年 第10卷 第1期   页码 16-38 doi: 10.1007/s11705-015-1545-z

摘要： As an advanced and new technology in molecular simulation fields, ReaxFF reactive force field has been developed and widely applied during the last two decades. ReaxFF bridges the gap between quantum chemistry (QC) and non-reactive empirical force field based molecular simulation methods, and aims to provide a transferable potential which can describe many chemical reactions with bond formation and breaking. This review presents an overview of the development and applications of ReaxFF reactive force field in the fields of reaction processes, biology and materials, including (1) the mechanism studies of organic reactions under extreme conditions (like high temperatures and pressures) related with high-energy materials, hydrocarbons and coals, (2) the structural properties of nanomaterials such as graphene oxides, carbon nanotubes, silicon nanowires and metal nanoparticles, (3) interfacial interactions of solid-solid, solid-liquid and biological/inorganic surfaces, (4) the catalytic mechanisms of many types of metals and metal oxides, and (5) electrochemical mechanisms of fuel cells and lithium batteries. The limitations and challenges of ReaxFF reactive force field are also mentioned in this review, which will shed light on its future applications to a wider range of chemical environments.

关键词： ReaxFF     reaction mechanism     nanomaterials     interfacial interaction     catalyst     fuel cell    

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cathode-electrolyte interface layer of lithium manganese oxide batteries from reactive force field (ReaxFF

Sahithya REDDIVARI, Christian LASTOSKIE, Ruofei WU, Junliang ZHANG

《能源前沿（英文）》 2017年 第11卷 第3期   页码 365-373 doi: 10.1007/s11708-017-0500-8

摘要： Lithium manganese oxide (LiMn O ) is a principal cathode material for high power and high energy density electrochemical storage on account of its low cost, non-toxicity, and ease of preparation relative to other cathode materials. However, there are well-documented problems with capacity fade of lithium ion batteries containing LiMn O . Experimental observations indicate that the manganese content of the electrolyte increases as an electrochemical cell containing LiMn O ages, suggesting that active material loss by dissolution of divalent manganese from the LiMn O surface is the primary reason for reduced cell life in LiMn O batteries. To improve the retention of manganese in the active material, it is key to understand the reactions that occur at the cathode surface. Although a thin layer of electrolyte decomposition products is known to form at the cathode surface, the speciation and reaction mechanisms of Mn in this interface layer are not yet well understood. To bridge this knowledge gap, reactive force field (ReaxFF) based molecular dynamics was applied to investigate the reactions occurring at the LiMn O cathode surface and the mechanisms that lead to manganese dissolution. The ReaxFFMD simulations reveal that the cathode-electrolyte interface layer is composed of oxidation products of electrolyte solvent molecules including aldehydes, esters, alcohols, polycarbonates, and organic radicals. The oxidation reaction pathways for the electrolyte solvent molecules involve the formation of surface hydroxyl species that react with exposed manganese atoms on the cathode surface. The presence of hydrogen fluoride (HF) induces formation of inorganic metal fluorides and surface hydroxyl species. Reaction products predicted by ReaxFF-based MD are in agreement with experimentally identified cathode-electrolyte interface compounds. An overall cathode-electrolyte interface reaction scheme is proposed based on the molecular simulation results.

关键词： lithium manganese oxide batteries     reactive force field (ReaxFF)     cathode-electrolyte interface layer     molecular dynamics    

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Chemical reactions of oily sludge catalyzed by iron oxide under supercritical water gasification condition

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 886-896 doi: 10.1007/s11705-021-2125-z

摘要： Supercritical water gasification is a promising technology in dealing with the degradation of hazardous waste, such as oily sludge, accompanied by the production of fuel gases. To evaluate the mechanism of Fe2O3 catalyst and the migration pathways of heteroatoms and to investigate the systems during the process, reactive force field molecular dynamics simulations are adopted. In terms of the catalytic mechanisms of Fe2O3, the surface lattice oxygen is consumed by small carbon fragments to produce CO and CO2, improving the catalytic performance of the cluster due to more unsaturated coordination Fe sites exposed. Lattice oxygen combines with •H radicals to form water molecules, improving the catalytic performance. Furthermore, the pathway of asphaltene degradation was revealed at an atomic level, as well as products. Moreover, the adsorption of hydroxyl radical on the S atom caused breakage of the two C–S bonds in turn, forming •HSO intermediate, so that the organic S element was fixed into the inorganic liquid phase. The heteroatom O was removed under the effects of supercritical water. Heavy metal particles presented in the oily sludge, such as iron in association with Fe2O3 catalyst, helped accelerate the degradation of asphaltenes.

关键词： oily sludge     SCWG     ReaxFF     Fe2O3     heteroatoms    

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Effect of styrene-butadiene-styrene copolymer on the aging resistance of asphalt: An atomistic understanding from reactive molecular dynamics simulations

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1261-1276 doi: 10.1007/s11709-021-0761-5

摘要： To reveal the potential influence of styrene-butadiene-styrene (SBS) polymer modification on the anti-aging performance of asphalt, and its mechanism, we explored the aging characteristics of base asphalt and SBS-modified asphalt by reaction force field (ReaxFF) and classical molecular dynamics simulations. The results illustrate that the SBS asphalt is more susceptible to oxidative aging than the base asphalt under oxygen-deficient conditions due to the presence of unsaturated C=C bonds in the SBS polymer. In the case of sufficient oxygen, the SBS polymer inhibits the oxidation of asphalt by restraining the diffusion of asphalt molecules. Compared with the base asphalt, the SBS asphalt exhibits a higher degree of oxidation at the early stage of pavement service and a lower degree of oxidation in the long run. In addition, SBS polymer degrades into small blocks during aging, thus counteracting the hardening of aged asphalt and partially restoring its low-temperature cracking resistance.

关键词： SBS asphalt     oxidative aging     asphalt hardening     ReaxFF     molecular dynamics    

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标题 作者 时间 类型 操作

Atomistic understanding of interfacial processing mechanism of silicon in water environment: A ReaxFF

期刊论文

Development, applications and challenges of ReaxFF reactive force field in molecular simulations

You Han, Dandan Jiang, Jinli Zhang, Wei Li, Zhongxue Gan, Junjie Gu

期刊论文

cathode-electrolyte interface layer of lithium manganese oxide batteries from reactive force field (ReaxFF

Sahithya REDDIVARI, Christian LASTOSKIE, Ruofei WU, Junliang ZHANG

期刊论文

Chemical reactions of oily sludge catalyzed by iron oxide under supercritical water gasification condition

期刊论文

Effect of styrene-butadiene-styrene copolymer on the aging resistance of asphalt: An atomistic understanding from reactive molecular dynamics simulations

期刊论文