Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 15
·6675-6684
·
IF 9.931
Guofeng Gao,Da Tie,Hao Ma,Haijun Yu,Shanshan Shi,Bo Wang,Shengming Xu,Linlin Wang,Yufeng Zhao
In this work, we report a novel design of mixed P2 + T phase NaxCo0.1Mn0.9O2 (0.44 ≤ x ≤ 0.7) with interface rich characteristics for high performance sodium storage, whereby the tunneled T phase offers fast Na ion diffusivity and excellent structural stability, the layered P2 phase contributes to high specific capacity, and the P2 + T phase interface offers additional channels and active sites for charge transfer and excess charge storage. Consequently, the as-prepared NaxCo0.1Mn0.9O2 (0.44 ≤ x ≤ 0.7) demonstrates an excellent discharge capacity of 219 mA h g−1 at a current rate of 0.1C (1C = 176 mA g−1), and retains 117 mA h g−1 even at a high rate of 5C. This outstanding performance is significantly superior to that of pure T-type Na0.44Co0.1Mn0.9O2 and P2-type Na0.7Co0.1Mn0.9O2, and also outperforms state-of-the-art manganese-based cathodes. The kinetic analysis indicates the drastically improved Na+ diffusion coefficient of the P2 + T phase, which is 6 and 200 times that of the pure T and P phases, respectively. The good reversibility and structural stability is evidenced through an ex situ XRD study.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
INORGANIC CHEMISTRY
·
2018
·
IF 4.7
Lizhu He,Zhen Song,Xionghui Jia,Zhiguo Xia,Quanlin Liu
T-phase (Ba,Ca)2SiO4:Eu2+, showing excellent luminescent thermal stability, has a positionally disordered structure with the splitting of five atom sites, but until now the reason has remained unclear. Herein, we investigate the coordination environments of each cation site in detail to understand the origins of the atom site splitting. We find that the three cation sites in the split-atom-site model are optimally bonded with ligand O atoms compared to the unsplit-atom-site model. This atom site splitting results in larger room and smaller room for each splitting cation site, which just accommodates larger Ba2+ ions and smaller Ca2+ ions, respectively, leading to more rigid structure. Based on the X-ray diffraction data refinement, the boundary of the T-phase for (Ba1–xCax)2SiO4 is redetermined. The Eu2+-doped T-phase (Ba,Ca)2SiO4 phosphors show excellent luminescent thermal stability, which can be attributed to optimal bonding and more rigid structure with atom site splitting. These results indicate that T-phase (Ba,Ca)2SiO4:Eu2+ phosphors have promise for practical applications.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
Energies
·
2022
·Vol. 15
·期 7
·2516
·
IF 3.252
Jingyu Zhong,Jing Ding,Jianfeng Lu,Xiaolan Wei,Weilong Wang
A computational study on thermal stability was conducted the first time, combining the modified quasi-chemical model, the Antoine equation, and the adiabatic flash evaporation calculation principle to design a method to calculate the system pressure-temperature (P-T) phase diagram of binary chloride molten salts. The evaporation temperature of the molten salt obtained by analyzing the P-T phase diagram of the eutectic molten salt clearly defined the upper limit of the optimal operating temperature of the mixed molten salt. The results indicated that the upper-temperature limits of NaCl-KCl, NaCl-CaCl2, KCl-CaCl2, NaCl-MgCl2, and KCl-MgCl2are determined to be 1141 K, 1151 K, 1176 K, 1086 K, and 1068 K. The maximum working temperature was measured experimentally using a thermogravimetric analysis (TGA), and the relative error between the calculation and experiment was calculated. The maximum error between the calculated and experimental values of the maximum operating temperature was 6.02%, while the minimum was 1.29%, demonstrating the method’s high accuracy. Combined with the lowest eutectic temperature and the upper-temperature limits of binary chloride molten salts, the stable operating temperature ranges of NaCl-KCl, NaCl-CaCl2, KCl-CaCl2, NaCl-MgCl2, and KCl-MgCl2are 891~1141 K, 750~1151 K, 874~1176 K, 732~1086 K, and 696~1086 K.Keywords:thermal stability calculation;upper-temperature limit;P-T phase diagram;modified quasi-chemical model;adiabatic flash calculation;binary chloride molten salts
研究领域:
能源科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 5
·1-6
·
IF 5.479
Ma Haiyan,Xue Ning,Wu Shujie,Li Zongbing,Miao Xiangmin
The authors describe a method for detection of Hg 2+ by using positively charged gold nanoparticles ((+)AuNPs) as a quencher of the fluorescence of DNA-capped silver nanoclusters (DNA-AgNCs) which are negatively charged. In the presence of Hg 2+ , a DNA duplex is formed through T-Hg 2+ -T coordination chemistry. The duplex can be digested by exonuclease III to form smaller DNA fragments. This leads to the release of the AgNCs and the recovery of fluorescence, best measured at excitation/emission wavelengths of 460/530 nm. The (+)AuNPs and Hg 2+ are also released and can be reused for target recycling signal amplification. Based on these findings, a method is worked out for the determination of Hg 2+ that works in the 5.0 pM to 10 nM concentration range and has a detection limit as low as 2.3 pM. It is highly selective because of the highly specific formation of T-Hg 2+ -T bonds.
By using ultrastable and positively charged gold nanoparticles as fluorescence quenchers and exonuclease assisted signal amplification, a method is developed for the sensitive and selective detection of Hg 2+ in water samples.
研究领域:
分析化学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Jingjing Wang,Chenxi Huang,Yue Xing,Xiang Shao
The hybridizations of two-dimensional (2D) metallic materials with semiconducting transition metal oxides (TMOs) register attractive heterojunctions, which can find various applications in photostimulated circumstances. In this work, we developed an ambient-pressure chemical vapor deposition method to directly grow T-VS2 on atomically smooth rutile TiO2 single crystals with different terminations and thus successfully constructed a heterojunction model of VS2/TiO2 with a well-defined clean interface. Detailed measurements with Kelvin probe force microscopy revealed the facet-dependent charge transfer occurring at the VS2/TiO2 interfaces, seeing variations not only in the amount and direction of the transferred electrons but also in the photoinduced surface potential changes and the dynamics of photogenerated charge carriers under ultraviolet irradiation. Interestingly, ultrathin T-VS2 was found with considerable magnetism at room temperature, disregarding the charge exchange with the TiO2 substrates. These results may bring deep insights into the photoinspired functionalities of the hybridized system combining metallic transition metal dichalcogenides and TMO materials.
研究领域:
材料科学
·
纳米技术
·
光化学
·
表面科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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