npj 2D Materials and Applications
·
2021
·Vol. 5
·期 1
·1-12
·
IF 11.106
Ren Xiaoyong,Yang Xiao,Xie Guoxin,He Feng,Wang Rong,Zhang Chenhui,Guo Dan,Luo Jianbin
Superlubricity has recently raised an increasing interest owing to its great potential in energy saving and environmental benefits. Yet how to obtain stable superlubricity under an ultrahigh contact pressure (>1 GPa) still remains a challenge. Here, we demonstrate that robust liquid superlubricity can be realized even under a contact pressure of 1193 MPa by lubrication with partially oxidized black phosphorus (oBP) nanosheets. The analysis indicates that the oBP nanosheets that absorb large amounts of water molecules are retained at the friction interface and transform the friction pairs interface to that between the oBP nanosheets. Molecular dynamics simulation demonstrates that water molecules could be retained at the friction interface even under the ultrahigh contact pressure owing to the abundant P=O and P–OH bonds formed on the oBP nanosheet surfaces, contributing to the achievement of stable superlubricity under the ultrahigh contact pressure. This work has the potential of introducing the liquid superlubricity concept in diverse industrial applications involving high-contact-pressure operating conditions.
研究领域:
材料科学
·
摩擦学
✓ 已验证
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Guanzheng Zhuang,Li Li,Mengyuan Li,Peng Yuan
Maya blue is an ancient hybrid pigment composed of indigo and microporous palygorskite , with a fantastic hue and outstanding stability. Its color-causing and stabilization mechanism are unsolved problems. In this work, different palygorskite materials were obtained by heating at 180, 300 and 570 °C, with raw palygorskite as a reference. Maya blue-like pigments were prepared from these palygorskite materials and solid indigo. The microporous structure of palygorskite and the status of inside water molecules were investigated by thermal analysis , X-ray diffraction, Fourier transform infrared and microporous analysis. The color properties, chemical resistance and photostability of pigments were characterized by reflectance spectra, CIE color parameters and color differences after the attack of concentrated nitric acid , dimethyl sulfoxide , and visible light exposure equaling to about 100 years. It was confirmed that the greenish-blue and stable hybrid pigment could only be prepared when indigo molecules were inserted into the micropores of palygorskite. Zeolitic water molecules inside the micropores should be removed because they hindered the insertion of indigo molecules. The key to immobilizing indigo molecules inside micropores was hydrogen bonds between indigo and coordinated water (C O … …H–OH). This study emphasized the important role of micropores and hydrogen bonds in the synthesis of organic-inorganic hybrid pigments.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2020
·
IF 3.408
Lei Cheng,Puxuan Yan,Xiulin Yang,Huahong Zou,Hu Yang,Hong Liang
Deeply understanding the structure and electrical properties of ZIF-8 is very important due to many practical applications of porous materials . We present the crystal structure and microstructure details of ZIF-8 prepared in three different solvents. The solvents play an important role on grain growth of ZIF-8, furthermore, a small fraction of monoclinic phase can be found in the ZIF-8s prepared in water or in amonium hydroxide. Radio-frequency dielectric and impedance spectra studies of dynamic dielectric response of ZIF-8s indicate two additional dielectric relaxation processes associated with the introduced water molecules in as-prepared samples. The dielectric response can be described by the combination of the dc conductivity, the universal dielectric response, the Cole-Cole relation and intrinsic response. The results exhibit the solvents make an important influence on the electrical properties due to different contents water in ZIF-8s. Our results will pave a way to modify the dielectric property of ZIF-based dielectrics in radio-frequency applications.
研究领域:
材料科学
·
电学性质研究
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Wanlun Jiang,Meng Su,Yangong Zheng,Teng Fei
Resistive humidity sensors are required in flexible and integrated devices. Two-dimensional MoO3 offers a large interface area, enabling the modulation of its electrical properties over a wide range. In this study, 2D MoO3 was synthesized via liquid-phase exfoliation for humidity-sensing tests. In terms of high sensitivity, negligible hysteresis, linearity, and stability, the humidity-sensing performance of MoO3 is superior to those of other materials. The sensitivity reaches 9794 Ω/RH at 25 °C. The sensing mechanism of MoO3 was investigated by using impedance spectra and voltage–current scans under different humidity levels. The results indicate that the resistance change of MoO3 due to humidity originates from the interfacial conductance. Interfacial H2O adsorption induces efficient conducting paths via hydrogen bonding, decreases the potential barrier for electron transfer, and supplies additional electron states to the valence bands. In this study, electronic humidity sensing was investigated in depth, and a new perspective was proposed for electronic humidity sensing.
研究领域:
材料科学
·
传感器技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nano Research
·
2020
·Vol. 14
·期 5
·1471-1478
·
IF 8.183
Shao Weiwei,Li Xiaodong,Zu Xiaolong,Liang Liang,Pan Yang,Zhu Junfa,Wang Chengming,Sun Yongfu,Xie Yi
Photooxidation provides a promising strategy for removing the dominant indoor pollutant of HCHO, while the underlying photooxidation mechanism is still unclear, especially the exact role of H 2 O molecules. Herein, we utilize in-situ spectral techniques to unveil the H 2 O-mediated HCHO photooxidation mechanism. As an example, the synthetic defective Bi 2 WO 6 ultrathin sheets realize high-rate HCHO photooxidation with the assistance of H 2 O at room temperature. In-situ electron paramagnetic resonance spectroscopy demonstrates the existence of •OH radicals, possibly stemmed from H 2 O oxidation by the photoexcited holes. Synchrotron-radiation vacuum ultraviolet photoionization mass spectroscopy and H 2 18 O isotope-labeling experiment directly evidence the formed •OH radicals as the source of oxygen atoms, trigger HCHO photooxidation to produce CO 2 , while in-situ Fourier transform infrared spectroscopy discloses the HCOO* radical is the main photooxidation intermediate. Density-functional-theory calculations further reveal the •OH formation process is the rate-limiting step, strongly verifying the critical role of H 2 O in promoting HCHO photooxidation. This work first clearly uncovers the H 2 O-mediated HCHO photooxidation mechanism, holding promise for high-efficiency indoor HCHO removal at ambient conditions.
研究领域:
环境科学
·
材料科学
·
化学
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Ximei Liang,Fangling Guan,Zhiyou Ling,Honghong Wang,Yunwen Tao,Elfi Kraka,Huajun Huang,Chenglong Yu,Danping Li,Jinbao He,Hansun Fang
Photodegradation of the insecticide pymetrozine (PYM) was studied on surface of wax films, and in aqueous and nonaqueous phase. The half-life of PYM on the wax surface was approximately 250 times longer than in water. Scavenging experiments, laser flash photolysis, and spectra analysis indicated the first singlet excited state of PYM (S1 * PYM ) to be the most important photoinduced species initiating the photodegradation. Quantum chemistry calculations identified significant molecular torsion and changes in the structure C–C N–N of S1 * PYM , and the absolute charges of the C N atoms increased and the bond strength weakened. Free energy surface analysis, and O 18 labeling experiments further confirmed that the mechanism was two-step photoinduced hydrolysis. The first step is the hydrolysis of S1 * PYM at C N upon reaction with 2–3 water molecules (one H 2 O molecule as the catalyst). The second step is an intramolecular hydrogen transfer coupled with the cleavage of C–N bond and formation of two cyclic products. During the interactions, water molecules experience catalytic activation by transferring protons, while there is a negligible solvent effect. Clarifying the detailed photodegradation mechanisms of PYM is beneficial for the development of green pesticides that are photostable and effective on leaf surfaces, and photolabile and detoxified in the aquatic environment.
研究领域:
环境科学
·
农药化学
·
量子化学
✓ 已验证
DOI
高影响因子
JOURNAL OF PHYSICS-CONDENSED MATTER
·
2022
·Vol. 34
·期 15
·154001
·
IF 2.745
Chunli Jiang,Qianqian Luo,Chunhua Luo,Hechun Lin,Hui Peng
We report here the synthesis of hybrid manganese halide crystals, (C4H7N2)MnCl3 · H2O and (C4H7N2)2MnCl4, by using the same organic ligand 2-methylimidazole. Upon heating treatment, the red-emissive (C4H7N2)MnCl3 · H2O crystal is structurally transformed into green-emissive (C4H7N2)2MnCl4 crystal in situ. The crystal structural analysis reveals that the [MnCl5 · H2O]3− octahedra chains decompose into mono [MnCl4]2− tetrahedra, accompanied by the departure of H2O molecules. Upon cooling in air or water vapor, the crystal structure and luminescence of (C4H7N2)2MnCl4 are transformed to those of (C4H7N2)MnCl3 · H2O. The in situ conversion of luminescence between (C4H7N2)MnCl3 · H2O and (C4H7N2)2MnCl4 provides new insight into the potential application of hybrid manganese halides.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2016
·
IF 2.74
Yong Zhou,Yongli Huang,Zengsheng Ma,Yinyan Gong,Xi Zhang,Yi Sun,Chang Q. Sun
A combination of the differential Raman spectrometrics and contact-angle measurements has enabled resolution of the hydrogen bond (HB, O:H O) relaxation and molecular dynamics in the NaX hydration shells. Observations suggest that the aqueous ions create each an electric field to form the hydration shells through O:H O bond elongation and polarization. The ionic polarization shares the same, and even stronger, effect of molecular undercoordination that shortens the H O bond and stiffen its phonon , and meanwhile, the O O Coulomb repulsivity lengthen and soften the O:H nonbond with an association of polarization. O:H O bond electrification raises not only the structure order of molecules and the viscosity in the hydration shells but also the skin stress and thermal stability of the solution. Exercises not only deepen our insight into the salt solute-solvent interaction involved in the Hofmeister series in terms of O:H O bond electrification but also provide a powerful means quantifying the dynamic, local, molecular-site-resolved information regarding the O:H O bond cooperativity in aqueous solutions.
研究领域:
物理化学
·
分子生物学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2015
·Vol. 78
·期 2
·293-298
·
IF 1.532
Cui Hongtao,Ma Wenle,Wang Li,Xue Junying
Abstract
In this work, α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ). The protonation and the following ring-opening reaction of epoxide promoted the hydrolysis of [Co(H 2 O) 6 ] 2+ , leading to the formation of α-Co(OH) 2 nanosheets. The obtained nanosheets were then exfoliated to monolayer nanosheets in formamide under ultrasonic vibration. A possible exfoliation mechanism is proposed for the exfoliating process of α-Co(OH) 2 nanosheets. The water molecules incorporated in the layered structure of α-Co(OH) 2 are considered to be the key medium for the layer exfoliation. It seems that the water molecules coordinated with the cobalt ions weakened the interlayer interaction. Therefore, the extraction of water molecules by formamide readily broke the interlayer connection in α-Co(OH) 2 , resulting in the exfoliation of nanosheets. Graphical Abstract α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ).
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
·
2025
·
IF 4.7
Lican Wang,Weikun Zhu,Jie Li,Junyi Yue,Jiangyao Chen
H 2 O shows a significant contribution to form oxygen- and hydrogen-containing products during photocatalytic oxidation of aromatic hydrocarbons. However, it was unclear what the roles of atoms in H 2 O in subsequent oxidation of these products. In this study, the photocatalytic oxidation of two aromatic alcohols, benzyl alcohol and phenethyl alcohol, on TiO 2 (79 % anatase and 21 % rutile) were investigated in mixed H 2 O (or H 2 18 O, D 2 O) and O 2 system. Aromatic aldehydes, acids and esters were main aromatic products, while modified TiO 2 and isotope-containing H 2 O did not change the product species. Aromatic aldehydes showed ≤ 0.19 % and ≤ 1.58 % of 18 O- and D-labeling rates, suggesting hardly involvement of H 2 O in their formation. Aromatic acids exhibited a 18 O-labeling rate range of 28.12 %-40.33 % and the highest D-labeling rate of 0.76 %, while a maximum enhancement of 18 O-labeling rate was 0.11 % in the –C=O group of the acids, indicating that H 2 O selectively provided O atom in the formation of –OH group of aromatic acids. The 18 O- and D-labeling rates of aromatic esters were in the range of 9.01 % to 15.95 % and 1.73 % to 8.08 %, suggesting that both oxygen and hydrogen atoms from H 2 O contributed to aromatic ester formation. Further analyzing mass fragmentation confirmed that H 2 O separately contributed its hydrogen and oxygen atoms to the –C=O and R–O groups of the esters. Based on the isotope tracing results, the contribution roles of H 2 O’s hydrogen and oxygen atoms in oxidation of aromatic alcohols to corresponding aromatic products were proposed. The findings in this study help to clarify the role of H 2 O in the oxidation process of aromatic alcohols at the atomic level and comprehensively reveal the oxidation mechanism of the aromatics.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Energy Chemistry
·
2024
·
IF 14
Xinhai Wang,Wensheng Yang,Shengshang Lu,Shangshu Peng,Tong Guo,Quan Xie,Qingquan Xiao,Yunjun Ruan
Aqueous potassium-ion batteries (APIBs), recognized as safe and reliable new energy devices, are considered as one of the alternatives to traditional batteries. Layered MnO 2 , serving as the main cathode, exhibits a lower specific capacity in aqueous electrolytes compared to organic systems and operates through a different reaction mechanism. The application of highly conductive graphene may effectively enhance the capacity of APIBs but could complicate the potassium storage environment. In this study, a MnO 2 cathode pre-intercalated with K + ions and grown on graphene (KMO@rGO) was developed using the microwave hydrothermal method for APIBs. KMO@rGO achieved a specific capacity of 90 mA h g −1 at a current density of 0.1 A g −1 , maintaining a capacity retention rate of >90% after 5000 cycles at 5 A g −1 . In-situ and ex-situ characterization techniques revealed the energy-storage mechanism of KMO@rGO: layered MnO 2 traps a large amount of “dead” water molecules during K + ions removal. However, the introduction of graphene enables these water molecules to escape during K + ions insertion at the cathode. The galvanostatic intermittent titration technique and density functional theory confirmed that KMO@rGO has a higher K + ions migration rate than MnO 2 . Therefore, the capacity of this cathode depends on the interaction between dead water and K + ions during the energy-storage reaction. The optimal structural alignment between layered MnO 2 and graphene allows electrons to easily flow into the external circuit. Rapid charge compensation forces numerous low-solvent K + ions to displace interlayer dead water, enhancing the capacity. This unique reaction mechanism is unprecedented in other aqueous battery studies.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
CRYSTAL GROWTH & DESIGN
·
2025
·
IF 3.4
Mengmeng Chen,Wangfei Che,Chen Cui,Qixian Ren,Juanjuan Lu,Yabo Wu
Exploring structure and property modulation strategies is crucial for developing functional crystal materials with superior properties. In this study, Na2ZnCl4·3H2O and Na2ZnCl4·2H2O crystals were synthesized using an aqueous solution evaporation method, and Na2ZnCl4 was synthesized using a high-temperature solution method. By varying the temperature, these compounds exhibit intriguing structural transformations and diverse structures following the removal of the water molecules. All these compounds possess a wide band gap, making them suitable for deep-ultraviolet (DUV) applications. Notably, the theoretical calculation results show that the noncentrosymmetric (NCS) compound Na2ZnCl4·3H2O exhibits a significant nonlinear optical (NLO) coefficient d33 = 1.73 pm/V in its largest direction, as determined by theoretical calculations, which is expected to be a candidate for additional periodic phase (APP) materials. This research provides significant implications for designing short-wavelength optical crystals and suggests that the incorporation of water molecules can significantly alter and enrich the crystal structures.
研究领域:
材料科学
·
晶体化学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）