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排序方式: 共有3498条查询结果,搜索用时 15 毫秒
91.
Zemin Sun Mengwei Yuan Kefan Shi Yuhui Liu Di Wang Dr. Caiyun Nan Dr. Huifeng Li Prof. Genban Sun Prof. Xiaojing Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(32):7244-7249
NiFe layered double hydroxides (LDHs) have been denoted as benchmark non-noble-metal electrocatalysts for the oxygen evolution reaction (OER). However, for laminates of NiFe LDHs, the edge sites are active, but the basal plane is inert, leading to underutilization as catalysts for the OER. Herein, for the first time, light and electron-deficient Li ions are intercalated into the basal plane of NiFe LDHs. The results of theoretical calculations and experiments both showed that electrons would be transferred from near Ni2+ to the surroundings of Li+, resulting in electron-deficient properties of the Ni sites, which would function as “electron-hungry” sites, to enhance surface adsorption of electron-rich oxygen-containing groups, which would enhance the effective activity for the OER. As demonstrated by the catalytic performance, the Li−NiFe LDH electrodes showed an ultralow overpotential of only 298 mV at 50 mA cm−2, which was lower than that of 347 mV for initial NiFe LDHs and lower than that of 373 mV for RuO2. Reasonable intercalation adjustment effectively activates laminated Ni2+ sites and constructs the electron-deficient structure to enhance its electrocatalytic activity, which sheds light on the functional treatment of catalytic materials. 相似文献
92.
Dr. You Xu Xingjie Chai Tianlun Ren Hongjie Yu Shuli Yin Dr. Ziqiang Wang Prof. Dr. Xiaonian Li Prof. Dr. Liang Wang Dr. Hongjing Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(70):16074-16080
The realization of water electrolysis on the basis of highly active, cost-effective electrocatalysts is significant yet challenging for achieving sustainable hydrogen production from water. Herein, N-doped Ni3S2/N-doped MoS2 1D hetero-nanowires supported by Ni foam (N-Ni3S2/N-MoS2/NF) are readily synthesized through a chemical transformation strategy by using NiMoO4 nanowire array growth on Ni foam (NiMoO4/NF) as the starting material. With the in situ generation of Ni3S2/MoS2 heterointerfaces within nanowires and the incorporation of N− anions, an extraordinary hydrophilic nature with abundant, well-exposed active sites and optimal reaction dynamics for both oxidation and reduction of water are obtained. Attributed to these properties, as-converted N-Ni3S2/N-MoS2/NF exhibits highly efficient electrocatalytic activities for both hydrogen and oxygen evolution reactions under alkaline conditions. The superior bifunctional properties of N-Ni3S2/N-MoS2/NF enable it to effectively catalyze the overall water-splitting reaction. 相似文献
93.
Nora Jannsen Dr. Stefano Diodati Nicola Dengo Francesca Tajoli Dr. Nicola Vicentini Dr. Giacomo Lucchini Prof. Adolfo Speghini Prof. Denis Badocco Prof. Paolo Pastore Prof. Silvia Gross 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(59):13624-13634
The aim of this work was i) to develop a hydrothermal, low-temperature synthesis protocol affording the upconverting hexagonal phase NaYF4 with suitable dopants while adhering to the “green chemistry” standards and ii) to explore the effect that different parameters have on the products. In optimizing the synthesis protocol, short reaction times and low temperatures (below 150 °C) were considered. Yb3+ and Er3+ ions were chosen as dopants for the NaYF4 material. Within the context of the second goal, parameters including nature of the precursors, treatment temperature, and treatment time were investigated to afford a pure hexagonal crystalline phase, both in the doped and undoped materials. To fully explore the synthesis results, the prepared materials were characterized from a structural (XRD), compositional (XPS, ICP-MS), and morphological (SEM) point of view. The upconverting properties of the compounds were confirmed by photoluminescence measurements. 相似文献
94.
Zhen Wang Xiaodong Lian Ruiting Li Xinglei Tao Prof. Yapei Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13811-13815
Photothermal materials (PTMs) have been intensively investigated in the fields of photothermal conversion. Superior to solid PTMs, liquid PTMs are leading the trends in satisfying the demands of high flexibility and easy recycling. Successful examples of liquid PTMs are mostly formulated by dispersing solid PTMs in solvents, but suffer from the problems of phase segregation and solvent pollution. In this work, a low-cost formulation is proposed, which involves an oxidative product of ethyl oleate by iodine. It is an intrinsic liquid PTM, preserving the fluidic nature as well as possessing considerable ability for photothermal conversion. In addition to understanding the mechanism of light absorption in the visible and even near infrared windows, two examples are presented to demonstrate the great potential of liquid PTMs in broad areas such as light sensing and energy storage. 相似文献
95.
A series of carbon-coated, nitrogen-doped titanium dioxide photocatalysts was produced and characterized. N-doped TiO2 powder samples were prepared using a sol-gel method and subsequently used for making doped-TiO2 thin films on glass substrates. Carbon layers were coated on the films by a thermal decomposition method using catechol. Diffuse reflectance spectra and Mott-Schottky analyses of the samples proved that nitrogen doping and carbon coating can slightly lower the band gap of TiO2, broaden its absorption to visible light and enhance its n-type character. According to photocatalytic tests against model contaminants, carbon-coated nitrogen-doped TiO2 films have better performance than simple TiO2 on the degradation of Rhodamine B dye molecules, but are poorly effective for degrading 4-chlorophenol molecules. Several possible explanations are proposed for this result, supported by scavenging experiments. This reveals the importance of a broad substrate scope when assessing new photocatalytic materials for water treatment, something which is often overlooked in many literature studies. 相似文献
96.
Kenna L. Salvatore Diana M. Lutz Dr. Haoyue Guo Dr. Shiyu Yue Joceline Gan Dr. Xiao Tong Dr. Ping Liu Dr. Esther S. Takeuchi Dr. Kenneth J. Takeuchi Dr. Amy C. Marschilok Dr. Stanislaus S. Wong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(42):9389-9402
Solution-based, anionic doping represents a convenient strategy with which to improve upon the conductivity of candidate anode materials such as Li4Ti5O12 (LTO). As such, novel synthetic hydrothermally-inspired protocols have primarily been devised herein, aimed at the large-scale production of unique halogen-doped, micron-scale, three-dimensional, hierarchical LTO flower-like motifs. Although fluorine (F) doping has been explored, the use of chlorine (Cl) dopants is the primary focus here. Several experimental variables, such as dopant amount, lithium hydroxide concentration, and titanium butoxide purity, were probed and perfected. Furthermore, the Cl doping process did not damage the intrinsic LTO morphology. The analysis, based on interpreting a compilation of SEM, XRD, XPS, and TEM-EDS results, was used to determine an optimized dopant concentration of Cl. Electrochemical tests demonstrated an increased capacity via cycling of 12 % for a Cl-doped sample as compared with pristine LTO. Moreover, the Cl-doped LTO sample described in this study exhibited the highest discharge capacity yet reported at an observed rate of 2C for this material at 143mAh g−1. Overall, these data suggest that the Cl dopant likely enhances not only the ion transport capabilities, but also the overall electrical conductivity of our as-prepared structures. To help explain these favorable findings, theoretical DFT calculations were used to postulate that the electronic conductivity and Li diffusion were likely improved by the presence of increased Ti3+ ion concentration coupled with widening of the Li migration channel. 相似文献
97.
Ann Feng Dr. Wei Cheng Dr. Jennifer Holter Dr. Neil Young Prof. Dr. Richard G. Compton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(20):6981-6986
The charging and controlled oxidative doping of single organometallic ferrocene nanoparticles is reported in aqueous sodium tetrafluoroborate using the nano‐impacts method. It is shown that ferrocene nanoparticles of approximately 105 nm diameter are essentially quantitatively oxidatively doped with the uptake of one tetrafluoroborate anion per ferrocene molecule at suitably high overpotentials. By using lower potentials, it is possible to achieve low doping levels of single nanoparticles in a controlled manner. 相似文献
98.
采用高压烧结技术制备了稀土元素Tb掺杂的n型Bi2Te2.7Se0.3基纳米晶块体热电材料.将高压烧结成型的样品于633 K真空退火36 h.研究了Tb掺杂量对样品的晶体结构和热电性能的影响.结果表明,高压烧结制备的样品为纳米结构, Tb掺杂使样品的晶胞体积变大,功率因子增大,热导率降低,从而使ZT值提高.Tb掺杂量为x=0.004是最优的掺杂量,该掺杂量的高压烧结样品经退火处理后,于373 K时ZT值达到最大为0.99,并且在323-473 K范围内, ZT值均大于0.8,这对用于温差发电领域具有重要意义. 相似文献
99.
《Physics letters. A》2020,384(26):126663
Based on the density functional theory, we discussed the electronic and optical properties of graphene/ WSe2 (GW) heterostructure after lanthanides doping. Red shift appears and the optical parameter values are improved in the low energy region after the lanthanides are doped. Different doping types are also discussed. In the case of single doping, substitute Yb atom on W site will improve the peak values of the optical parameters greatly. In the case of co-doping, it is found that the effect will be more obvious when the two doped lanthanide atoms are located in the second neighboring positons. These results suggest that lanthanides doping does adjust the electronic structure and improve the optical properties of GW heterostructures, which providing useful guidance for the design of novel optical nanodevices based on two-dimensional materials. 相似文献
100.
Dr. Naixia Lv Jie Yin Wendi Fu Jinrui Zhang Yujun Li Dr. Ding Jiang Dr. Hongping Li Prof. Wenshuai Zhu 《Chemphyschem》2021,22(2):168-177
The rational design of highly active hexagonal boron nitride (h-BN) catalysts at the atomic level is urgent for aerobic reactions. Herein, a doping impurity atom strategy is adopted to increase its catalytic activities. A series of doping systems involving O, C impurities and B, N antisites are constructed and their catalytic activities for molecular O2 have been studied by density functional theory (DFT) calculations. It is demonstrated that O2 is highly activated on ON and BN defects, and moderately activated on CB and CN defects, however, it is not stable on NB and OB defects. The subsequent application in oxidative desulfurization (ODS) reactions proves the ON and C-doped (CB, CN) systems to be good choice for sulfocompounds oxidization, especially for dibenzothiophene (DBT). While the BN antisite is not suitable for such aerobic reaction due to the extremely stable B−O*−B species formed during the oxidation process. 相似文献