Yannan Zhou  Qun Xu  Tianpei Ge  Xiaoli Zheng  Li Zhang  Pengfei Yan 《Angewandte Chemie (International ed. in English)》2020,59(8):3322-3328

In two‐dimensional (2D) amorphous nanosheets, the electron–phonon coupling triggered by localization of the electronic state as well as multiple‐scattering feature make it exhibit excellent performance in optical science. VS₂ nanosheets, especially single‐layer nanosheets with controllable electronic structure and intrinsic optical properties, have rarely been reported owing to the limited preparation methods. Now, a controllable and feasible switching method is used to fabricate 2D amorphous VS₂ and partial crystallized 2D VO₂(D) nanosheets by altering the pressure and temperature of supercritical CO₂ precisely. Thanks to the strong carrier localization and the quantum confinement, the unique 2D amorphous structures exhibit full band absorption, strong photoluminescence, and outstanding photothermal conversion efficiency.  相似文献   

    

Gaoxiang Liu  Nikita Fedik  Chalynette Martinez‐Martinez  Sandra M. Ciborowski  Xinxing Zhang  Alexander I. Boldyrev  Kit H. Bowen 《Angewandte Chemie (International ed. in English)》2020,59(23):8760-8764

We reply to the comment by S. Pan and G. Frenking who challenged our interpretation of the Na^?:→BH₃ dative bond in the recently synthesized NaBH₃^? cluster. Our conclusion remains the same as that in our original paper ( https://doi.org/10.1002/anie.201907089 and https://doi.org/10.1002/ange.201907089 ). This conclusion is additionally supported by the energetic pathways and NBO charges calculated at UCCSD and CASMP2(4,4) levels of theory. We also discussed the suitability of the Laplacian of electron density (QTAIM) and Adaptive Natural Density Partitioning (AdNDP) method for bond type assignment. It seems that AdNDP yields more sensible results. This discussion reveals that the complex realm of bonding is full of semantic inconsistencies, and we invite experimentalists and theoreticians to elaborate this topic and find solutions incorporating different views on the dative bond.  相似文献   

    

Wenbin Wang  Yutang Wang  Ruoou Yang  Qunlei Wen  Youwen Liu  Zheng Jiang  Huiqiao Li  Tianyou Zhai 《Angewandte Chemie (International ed. in English)》2020,59(39):16974-16981

Electrochemical synthesis based on electrons as reagents provides a broad prospect for commodity chemical manufacturing. A direct one‐step route for the electrooxidation of amino C?N bonds to nitrile C≡N bonds offers an alternative pathway for nitrile production. However, this route has not been fully explored with respect to either the chemical bond reforming process or the performance optimization. Proposed here is a model of vacancy‐rich Ni(OH)₂ atomic layers for studying the performance relationship with respect to structure. Theoretical calculations show the vacancy‐induced local electropositive sites chemisorb the N atom with a lone pair of electrons and then attack the corresponding N(sp³)?H, thus accelerating amino C?N bond activation for dehydrogenation directly into the C≡N bond. Vacancy‐rich nanosheets exhibit up to 96.5 % propionitrile selectivity at a moderate potential of 1.38 V. These findings can lead to a new pathway for facilitating catalytic reactions in the chemicals industry.  相似文献   

    

Dr. Zhi Li  Dr. Weina Qian  Dr. Hui Guo  Dr. Xu Long  Dr. Yuping Tang  Prof. Dr. Jianbin Zheng 《ChemElectroChem》2020,7(7):1581-1589

In this study, a non-enzymatic electrochemical sensor was developed based on bracelet-like Au@Pt nanoparticles (B−Au@Pt NPs) and used for extremely sensitive detection of hydrogen peroxide (H₂O₂). The uniquely shaped B−Au@Pt NPs with a well-defined core–shell structure were synthesized by a combination of seed-mediated growth and electrostatic self-assembly, especially using both sodium citrate (SC) and cetyltrimethylammonium chloride (CTAC). Through characterization by dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM) and UV/Vis absorption spectra, it was evident that each Au NP was surrounded by several ultrasmall Pt NPs, all of which were detached from and lose contact with Au cores. Compared with sea urchin-like Au@Pt NPs (S−Au@Pt NPs) synthesized only by a seed-mediated growth, B−Au@Pt NPs presented obvious electrochemical response and exhibited substantially enhanced electrocatalytic activity towards H₂O₂ reduction. This H₂O₂ sensor, denoted as B−Au@Pt NPs/GCE (GCE=glassy carbon electrode), with enhanced sensitivity, has shown much better sensing performance than other sensors based on Pt reported earlier, particularly the high sensitivity of 882.2 μA mM⁻¹ cm⁻². Moreover, this non-enzymatic electrochemical sensor based on B−Au@Pt NPs may offer the potential for sensitive detection of H₂O₂ in aquatic environmental monitoring.  相似文献   

    

Dr. Zhenfei Li  Dr. Xin Ren  Dr. Weichao Tian  Dr. Yi Zheng  Dr. Jiachen Sun  Dr. Liwei An  Dr. Lizhi Wen  Prof. Li Wang  Prof. Guangchuan Liang 《ChemElectroChem》2020,7(9):2174-2183

High tap density and superior electronic conductivity of LiFePO₄/KB was synthesized by a combination of wet ball-milling, spray drying, and carbothermal reduction with Ketjen black (KB) as a carbon additive. KB is a conductive carbon black with the special chain-like structure. When KB is used to coat on the surface of primary particles of LiFePO₄, the chain-like structure can form a developed 3D network structure between the primary particles of LiFePO₄. This special structure can not only provide conductive channels for electrons but also cause the primary particles of LiFePO₄ to aggregate tightly. Comparing to the conventional carbon coating materials (only glucose as the carbon source) with a low volumetric energy density of 452.5 Wh L⁻¹ at 1 C rate, we simultaneously increased the electrical conductivity (7.8×10⁻² S cm⁻¹) and tap density (1.6 g cm⁻³) by adding KB, resulting in a higher volumetric energy density of 829.9 Wh L⁻¹ at 1 C rate. When KB is added at 5 % of glucose mass, the LiFePO₄/KB composite shows an excellent discharge capacity of 161.6 mAh g⁻¹ at 0.2 C and the 97.7 % retention rate after 500 cycles at 5 C.  相似文献   

    

Dr. Ruixian Tang  Lei Ma  Yu Zhang  Xiao Zheng  Yongji Shi  Xiangyu Zeng  Xiaoyu Wang  Prof. Liangming Wei 《ChemElectroChem》2020,7(9):1952-1952

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Hao Wang  Ruixin Zheng  Prof. Chaozhu Shu  Prof. Jianping Long 《ChemElectroChem》2020,7(24):4922-4930

Lithium-carbon dioxide (Li-CO₂) batteries are considered as a most auspicious energy storage systems owing to their high capacity and the ability of capturing CO₂. However, there are still some critical issues needed to be addressed before their practical application, such as high charge potential and poor cyclability. Herein, oxygen vacancy-enriched TiO₂ nanoparticles grown in situ on Ti₃C₂T_x MXene (O_V-TiO₂/MXene) are synthesized as catalysts for Li-CO₂ batteries by facile one-step ethanol heat treatment of the MXene nanosheets. The thermodynamically metastable Ti atom on the surface of MXenes serves as nucleating sites, which play a critical role in generating the relatively stable vacancy-rich TiO₂ nanoparticles. The spontaneously generated oxygen vacancies can enhance CO₂ adsorption, which is beneficial to CO₂ involved electrode reactions. The Li-CO₂ batteries with O_V-TiO₂/MXene electrodes deliver noteworthily reduced charge voltage of 3.37 V at 100 mA g⁻¹, and a superb cycling performance of 158 cycles. This work highlights the significant role of oxygen vacancies in activating CO₂ in Li-CO₂ batteries, instrumental to the development of high-performance electrocatalysts for Li-CO₂ batteries and beyond.  相似文献   

    

Dr. Cordula Braun  Liuda Mereacre  Weibo Hua  Dr. Tobias Stürzer  Dr. Ilia Ponomarev  Prof. Dr. Peter Kroll  Prof. Dr. Adam Slabon  Zheng Chen  Yann Damour  Prof. Dr. Xavier Rocquefelte  Prof. Dr. Jean-François Halet  Dr. Sylvio Indris 《ChemElectroChem》2020,7(22):4504-4504

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Dr. Cordula Braun  Liuda Mereacre  Weibo Hua  Dr. Tobias Stürzer  Dr. Ilia Ponomarev  Prof. Dr. Peter Kroll  Prof. Dr. Adam Slabon  Zheng Chen  Yann Damour  Prof. Dr. Xavier Rocquefelte  Prof. Dr. Jean-François Halet  Dr. Sylvio Indris 《ChemElectroChem》2020,7(22):4550-4561

The carbodiimide SnCN₂ was prepared at low temperatures (400 °C–550 °C) by using a patented urea precursor route. The crystal structure of SnCN₂ was determined from single-crystal data in space group C2/c (no. 15) with a=9.1547(5), b=5.0209(3), c=6.0903(3) Å, β=117.672(3), V=247.92 ų and Z=4. As carbodiimide compounds display remarkably high thermal and chemical resistivity, SnCN₂ has been doped with Eu and Tb to test it for its application in future phosphor-converted LEDs. This doping of SnCN₂ proved that a color tuning of the carbodiimide host with different activator ions and the combination of the latter ones is possible. Additionally, as the search for novel high-performing electrode materials is essential for current battery technologies, this carbodiimide has been investigated concerning its use in lithium-ion batteries. To further elucidate its application possibilities in materials science, several characterization steps and physical measurements (XRD, in situ XANES, Sn Mössbauer spectroscopy, thermal expansion, IR spectroscopy, Mott-Schottky analysis) were carried out. The electronic structure of the n-type semiconductor SnCN₂ has been probed using X-ray absorption spectroscopy and density functional theory (DFT) computations.  相似文献   

    

Dr. Zhenping Qiu  Dr. Yelong Zhang  Dr. Zheng Liu  Dr. Yan Gao  Dr. Jiaming Liu  Prof. Qingguang Zeng 《ChemElectroChem》2020,7(18):3811-3817

Layered nickel-rich transition metal oxide has been receiving much attention as high-energy-density cathode materials for rechargeable lithium-ion batteries. However, the severe capacity fading caused by bulk structural degradation of Ni-rich cathodes during lithiation/delithiation obstructs their commercialization. Herein, we modify the LiNi_0.92Co_0.06Al_0.02O₂ (NCA92) cathode materials by W⁶⁺ cation and BO₃³⁻ polyanion co-doping to improve the structural stability and upgrade the electrochemical reversibility. The co-doped NCA92 materials show remarkably improved cycling stability at 1 C with a capacity retention of 93.4 % after 100 cycles, whereas the pristine cathodes exhibit poor capacity retention of 53.0 % and suffer severe structural deterioration. Further studies reveal that the particle fragmentation resulted from the inherent internal strain and the structural degradation upon cycling can be effectively mitigated by W⁶⁺ cation and BO₃³⁻ polyanion co-doping. Besides, W⁶⁺ and BO₃³⁻ co-doping could enlarge the interlayer spacing of NCA92, thus increasing lithium-ion diffusion coefficient, which is conducive to enhancing the rate capability. The present work demonstrates that cationic-anionic co-doping is an effective strategy to maintain the structural stability of Ni-rich cathode materials, and it promotes the development of stable cathode materials for high energy density lithium-ion batteries.  相似文献