Deep eutectic solvents (DESs) serve as functionalized solvents with superior lubricating properties. However, limited research has been conducted on their application for modifying and treating nanomaterials as nonpolar lubricant additives. Consequently, this paper presents the synthesis of a menthol/thymol/tetradecylphosphonic acid oil-soluble ternary DES, which was employed to modify and treat MXene. The DES facilitates the expansion of MXene's interlayer spacing, while the grafting of long carbon chains in the DES enhances the dispersion stability of MXene in nonpolar lubricants. Furthermore, the tribological properties of DES complexed MXene lubricant additives were examined, revealing a reduction in the coefficient of friction and wear rate by 46.6 and 56.8% for both 0.1 wt % DES/MXene and 2 wt % DES base oil at 25 degrees C, and by 40.3 and 48.1% at 100 degrees C, respectively. The superior lubrication performance is attributed to optimal dispersion stability, exceptional wettability, and the synergistic impact of the dual lubrication film created by DES and the interlayer shear mechanism of MXene.

In this study, polydopamine-modified graphene oxide (PGO) nanomaterials were prepared based on the self-polymerization of dopamine in a weakly alkaline environment. In the friction experiment, the lubricants with 0.15 wt% PGO nanomaterials have optimal friction properties. Subsequently, X-ray photoelectron spectroscopy (XPS), X-ray energy spectroscopy (EDS), and laser Raman spectroscopy were performed on the wear scar. Compared to pure oil, the friction coefficient was reduced by 31%, and the trace width was reduced by 47.69%. In addition, molecular dynamics simulations showed that PGO has the lowest diffusion coefficient among n-hexadecane and the interaction energy between PGO and n-hexadecane molecules was the largest, and oil droplets containing PGO exhibited the best adsorption performance on the surface of the Si3N4/GCr15. The results showed that compared with other additives, PGO as a lubricant additive can play a significant role in reducing friction and anti-wear.

In this study, we successfully synthesized CD@CuCo-MOF composites, which are composed of ultrathin twodimensional (2D) nanosheets of metal-organic framework (MOF) doped with carbon dots (CDs). The synthesis process involved hydrothermal and ultrasonically assisted self-assembly with a proper solvent ratio. The composites were then dispersed into pentaerythritol ester (PETE) with the aid of ultrasonic treatment. We thoroughly evaluated the physicochemical features and tribological properties of the CD@CuCo-MOF composites using advanced testing and characterization techniques including XRD, Raman, FTIR, TG, XPS, FIB-TEM and so on. The results demonstrated that the addition of CD@CuCo-MOF resulted in a 61.1 % reduction in the coefficient of friction (COF) at a concentration of 0.1 wt% when compared to the base oil at room temperature. With the rise in temperature, CD@CuCo-MOF exhibited excellent lubricating properties due to its hybrid inorganic-organic structure and interlayer sliding effect. This led to a reduction of 59.2 % and 42.9 % in the mean COF compared to PETE oil at temperatures of 100 degrees C and 200 degrees C. This enhancement in the tribological performance of CD@CuCo-MOF could be attributed to several factors, including its superior dispersion stability, excellent lubricating properties, and involvement in the formation of a tribofilm. The tribofilm formed from a combination of CDs, CuCo-MOF, metal oxides, carbides, and nitrides promoted the rearrangement of the contact surface, thereby minimizing the friction and wear between the rubbing surfaces. These findings hold significant guiding implications for advancing the development of potential-controlled lubrication using MOFs doped with CDs across a wide temperature range.

As an efficient, safe, and environmentally friendly technology, semiconductor photocatalysis has been widely used in the removal of antibiotics from wastewater. In this work, a novel Ag/BiOI/g-C3N4 composite photocatalytic material, BiOI/g-C3N4, g-C3N4, and BiOI are prepared as the photocatalysts. The morphologies, chemical properties, and photocatalytic performances of the photocatalysts are characterized using scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectrometer, ultraviolet-visible spectroscopy (UV-Vis) diffuse reflectance spectra, and photoluminescence spectra. In addition, tetracycline hydrochloride (TC) and ceftiofur sodium aqueous solutions are used to simulate wastewater and the photocatalytic degradation performances of the photocatalysts are investigated and compared under visible light. Compared to g-C3N4, BiOI, and BiOI/g-C3N4, the Ag/BiOI/g-C3N4 demonstrates superior performance, increasing the removal rates of TC and ceftiofur sodium to 85.6% and 90.2%, respectively. The photocatalytic mechanism of the Ag/BiOI/g-C3N4 may involve the promotion of the visible light-harvesting ability and inhibition of the recombination of photogenerated electron/hole pairs. Furthermore, the primary active groups in the system are identified as superoxide radicals (& BULL;O-2(-)) and hydroxyl radicals (& BULL;OH). Herein, some valuable insights into the development of innovative photocatalytic materials are offered for the effective removal of antibiotics from water.

Purpose - The purpose of this study is to prepare ZnFe2O4 nanospheres, sheet MoS2 and three ZnFe2O4@MoS2 core-shell composites with various shell thicknesses, and add them to the base oil for friction and wear tests to simulate the wear conditions of hybrid bearings.Design/methodology/approach - Through the characterization and analysis of the morphology of wear scars and the elemental composition of friction films, the tribological behavior and wear mechanism of sample materials as lubricant additives were investigated and the effects of shell thickness and sample concentration on the tribological properties of core-shell composite lubricant additives were discussed.Findings - The findings demonstrate that each of the five sample materials can, to varying degrees, enhance the lubricating qualities of the base oil and that the core-shell nanocomposite sample lubricant additive has superior lubricating properties to those of ZnFe2O4 and MoS2 alone, among them ZnFe2O4@MoS2-2 core-shell composites with moderate shell thickness performed most ideally. In addition, the optimal concentration of the ZnFe2O4@MoS2 lubricant additive was 0.5 Wt.%, and a concentration that was too high led to particle deposition and affected the friction effect. Originality/value - In this work, ZnFe2O4@MoS2 core-shell composites were synthesized for the first time using ZnFe2O4 as the carrier and the lubrication mechanism of core-shell composites and single materials were compared and studied, which illustrated the advantages of core-shell composite lubricant additives. At the same time, the influence of different shell thicknesses on the lubricant additives of core-shell composites was studied.Peer review - The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2022-0367/

Carbon quantum dots (CQDs) doped with silver (Ag-CQDs) was prepared using a facile hydrothermal method. With the combination of ultrasound vibration and ionic liquid (IL), the dispersion stability of the Ag-CQDs additive in poly alpha olefin (PAO) was improved. The tribological performance of the CQDs and Ag-CQDs as additives over a wide temperature range were evaluated through four-ball tests and a ball-on-disk reciprocating configuration. The four-ball test results revealed that the CQDs and Ag-CQDs additives could effectively reduce the coefficient of friction (COF) of the base oil and wear scar diameter (WSD) of lower balls. When the concentration was 0.05 wt%, the Ag-CQDs additive could lead to 42.2% lower COF and 35.3% lower WSD than the base oil. Meanwhile, the tribological performance at elevated temperatures results revealed that the CQDs and Ag-CQDs additives could substantially decrease friction and wear when the ambient temperature was above 200 degrees C. The Ag-CQDs exhibited better lubricating performance than the CQDs. The lubricating mechanism was attributed to the formation of a tribofilm composed of Ag-CQDs, multicomponent oxides, carbonates and nitrides induced by tribochemical reactions, which provided effective protection for the rubbing pair and maintained low friction and wear.

High-pressure polymorphism is a developing interdisciplinary field. Pressure up to 20 GPa is a powerful thermodynamic parameter for the study and fabrication of hydrogen-bonded polymorphic systems. This review describes how pressure can be used to explore polymorphism and surveys the reports on examples of compounds that our group has studied at high pressures. Such studies have provided insight into the nature of structure-property relationships, which will enable crystal engineering to design crystals with desired architectures through hydrogen-bonded networks. Experimental methods are also briefly surveyed, along with two methods that have proven to be very helpful in the analysis of high-pressure polymorphs, namely, the ab initio pseudopotential plane-wave density functional method and using Hirshfeld surfaces to construct a graphical overview of intermolecular interactions.

目的 制备纳米SiO2改性水性环氧树脂涂料，并对其耐磨性能进行研究。方法 在水性环氧树脂涂料的基础上添加质量分数为1%、2%、3%、4%、5%的纳米SiO2对涂料进行改性，将一部分制得的纳米SiO2改性水性环氧树脂涂料涂在处理好的马口铁片上，其余部分则浇筑在自制的哑铃型模具中，制备出两种不同的试样，用来进行红外光谱表征、SEM、涂层力学性能测试、涂层耐磨性测试、涂层吸水性测试以及涂料黏度测试。结果 当纳米SiO2质量分数为2%时，涂层硬度达到6 H,附着力等级为0,耐冲击高度达50 cm,拉伸强度为43.27 MPa,磨耗质量为0.000 2g,摩擦系数为0.037 5,涂料适用期为40 min,涂层抗弯曲性、吸水性良好。结论 改性后涂层的吸水性下降，力学性能、耐磨性显著提高，纳米SiO2的分散性良好，未发生团聚现象。

The TiB2/Cr multilayered coatings were deposited on the 304 stainless steel substrates by a D.C. magnetron sputtering system. The mechanical properties and wide-temperature tribological performances of the coatings were carefully studied using scanning electron micrograph, X-ray diffractometer, Raman spectra, nanoindentation, residual stress tester and scratch tester. The results indicated that the mechanical properties including residual compressive stress, adhesion strength and fracture toughness of TiB2/Cr multilayer coating presented well, which could be attributed to the reason that the Cr interlayer absorbed part of the residual compressive stress through plastic deformation. Meanwhile, the multilayer coatings improved tribological performances because of the formation of lubricated oxides on the wear track in the temperature range of 25 degrees C-400 degrees C. The reaction between TiB2 and O-2 occurred at high temperatures giving rise to the B2O3, which was a kind of high-temperature lubricant. The lowest friction coefficient of 0.48 +/- 0.02 was revealed at 400 degrees C, whereas the wear rate was (10.1 +/- 0.407) x 10(-5) mm(3)/N.m. The upward wear rate for multilayer coatings was mainly due to a severe frictional oxidation reaction on the whole friction surface at high temperatures, making the surface of coating in the dynamic process of oxidation-wear-remove. The main wear mechanism of the coating was considered to be abrasive wear at room temperature, then it transformed into abrasive wear and oxidation wear at high temperature when the coating slid against Si3N4 ball. (C) 2021 The Author(s). Published by Elsevier B.V.

石墨烯常被使用在润滑油中,以此提高油的润滑性能,但其在油中极易发生团聚,需要借助分散剂抑制团聚。石墨烯、分散剂及润滑油间分子行为可揭示分散机理、润滑机理及协同作用。采用对环境无毒无害的span60作为分散剂,基于分子动力学研究