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991.
Shiqiang Zhuang Eon Soo Lee Lin Lei Bharath Babu Nunna Liyuan Kuang Wen Zhang 《国际能源研究杂志》2016,40(15):2136-2149
Platinum group metal‐based (PGM) catalysts are widely applied in many electrochemical systems such as fuel cells or metal–air batteries because of their excellent catalytic performance. But the high raw material cost of PGM catalysts has become a significant issue. In recent years, huge efforts have been made to reduce the material cost of electrochemical systems by developing non‐PGM catalysts, and as one of the promising non‐PGM catalysts, nitrogen‐doped graphene (N‐G) has emerged. In this research, nanoscale high‐energy wet ball milling methodology was investigated as an effective synthesis method for N‐G catalysts by using graphene oxide and melamine as raw materials. The main purpose is to study reaction mechanism of the synthesis process and the physical, chemical, and electrochemical properties of N‐G catalysts generated by this mechanochemical approach. The elemental composition, chemical bonding composition, and electron transfer number of the synthesized products were characterized. The results show that the electron transfer number of the N‐G catalyst with 23.2 at% nitrogen doping content, synthesized by the high‐energy wet ball milling method, has attained a value of 3.87, which is close to the number (3.95) of Pt/C catalysts, and the grinding time was found to be a significant factor in the properties of N‐G catalysts in the experiments. The results also show that the high‐energy wet ball milling developed in this research is a promising method to synthesize high‐performance N‐G catalysts with a simple and easy controllable approach. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
992.
Seong Mok Cho Chil Seong Ah Tae‐Youb Kim Juhee Song Hojun Ryu Sang Hoon Cheon Joo Yeon Kim Yong Hae Kim Chi‐Sun Hwang 《ETRI Journal》2016,38(3):469-478
In this paper, we investigate the effects of pre‐reducing Sb‐doped SnO2 (ATO) electrodes in viologen‐anchored TiO2 (VTO) nanostructure–based electrochromic devices. We find that by pre‐reducing an ATO electrode, the operating voltage of a VTO nanostructure–based electrochromic device can be lowered; consequently, such a device can be operated more stably with less hysteresis. Further, we find that a pre‐reduction of the ATO electrode does not affect the coloration efficiency of such a device. The aforementioned effects of a pre‐reduction are attributed to the fact that a pre‐reduced ATO electrode is more compatible with a VTO nanostructure–based electrochromic device than a non‐pre‐reduced ATO electrode, because of the initial oxidized state of the other electrode of the device, that is, a VTO nanostructure–based electrode. The oxidation state of a pre‐reduced ATO electrode plays a very important role in the operation of a VTO nanostructure–based electrochromic device because it strongly influences charge movement during electrochromic switching. 相似文献
993.
Heavy metal oxide B2O3–PbO–Bi2O3–GeO2 transparent glass doped with Sm3+ was synthesized and implanted with Au+ using energy of 300 keV and fluence of 1 × 1016 cm−2. The annealing of the implanted glass at moderate temperature below the glass transition temperature induced the nucleation of gold nanoparticles, confirmed by the characteristic absorption band in the visible range and by transmission electron microscopy. Using Miés and Doylés theories for the surface plasmon resonance, the average size of the gold nanoparticles was about 4.6 nm, similar to the values observed by transmission electron microscopy. It was also observed the crystallization of a thin layer of the glass at the implanted surface after annealing, detected by X-ray diffraction and scanning electron microscope. Visible and near-infrared emission of Sm3+ was enhanced after annealing of the glass implanted with gold. Judd–Ofelt parameters and radiative parameters were calculated for the glass doped with Sm3+ with and without gold nanoparticles. 相似文献
994.
995.
Xuhui Xu Wenfei Zhang Decheng Yang Wei Lu Jianbei Qiu Siu Fung Yu 《Advanced materials (Deerfield Beach, Fla.)》2016,28(36):8045-8050
996.
Gao‐Feng Chen Xian‐Xia Li Li‐Yi Zhang Nan Li Tian Yi Ma Zhao‐Qing Liu 《Advanced materials (Deerfield Beach, Fla.)》2016,28(35):7680-7687
997.
998.
Ting‐Zheng Hou Xiang Chen Hong‐Jie Peng Jia‐Qi Huang Bo‐Quan Li Qiang Zhang Bo Li 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(24):3283-3291
Lithium–sulfur (Li–S) batteries have been intensively concerned to fulfill the urgent demands of high capacity energy storage. One of the major unsolved issues is the complex diffusion of lithium polysulfide intermediates, which in combination with the subsequent paradox reactions is known as the shuttle effect. Nanocarbon with homogeneous nonpolar surface served as scaffolding materials in sulfur cathode basically cannot afford a sufficient binding and confining effect to maintain lithium polysulfides within the cathode. Herein, a systematical density functional theory calculation of various heteroatoms‐doped nanocarbon materials is conducted to elaborate the mechanism and guide the future screening and rational design of Li–S cathode for better performance. It is proved that the chemical modification using N or O dopant significantly enhances the interaction between the carbon hosts and the polysulfide guests via dipole–dipole electrostatic interaction and thereby effectively prevents shuttle of polysulfides, allowing high capacity and high coulombic efficiency. By contrast, the introduction of B, F, S, P, and Cl monodopants into carbon matrix is unsatisfactory. To achieve the strong‐couple effect toward Li2Sx, the principles for rational design of doped carbon scaffolds in Li–S batteries to achieve a strong electrostatic dipole–dipole interaction are proposed. An implicit volcano plot is obtained to describe the dependence of binding energies on electronegativity of dopants. Moreover, the codoping strategy is predicted to achieve even stronger interfacial interaction to trap lithium polysulfides. 相似文献
999.
Shiyong Chu Yijun Zhong Rui Cai Zhaobao Zhang Shenying Wei Zongping Shao 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(48):6724-6734
A simple and green method is developed for the preparation of nanostructured TiO2 supported on nitrogen‐doped carbon foams (NCFs) as a free‐standing and flexible electrode for lithium‐ion batteries (LIBs), in which the TiO2 with 2.5–4 times higher loading than the conventional TiO2‐based flexible electrodes acts as the active material. In addition, the NCFs act as a flexible substrate and efficient conductive networks. The nanocrystalline TiO2 with a uniform size of ≈10 nm form a mesoporous layer covering the wall of the carbon foam. When used directly as a flexible electrode in a LIB, a capacity of 188 mA h g?1 is achieved at a current density of 200 mA g?1 for a potential window of 1.0–3.0 V, and a specific capacity of 149 mA h g?1 after 100 cycles at a current density of 1000 mA g?1 is maintained. The highly conductive NCF and flexible network, the mesoporous structure and nanocrystalline size of the TiO2 phase, the firm adhesion of TiO2 over the wall of the NCFs, the small volume change in the TiO2 during the charge/discharge processes, and the high cut‐off potential contribute to the excellent capacity, rate capability, and cycling stability of the TiO2/NCFs flexible electrode. 相似文献
1000.
Santosh K. Singh Deepak Kumar Vishal M. Dhavale Sourav Pal Sreekumar Kurungot 《Advanced Materials Interfaces》2016,3(20)
Development of an efficient and durable water splitting electrocatalyst holds a great commitment for the future energy devices. The real application of oxygen evolution reaction (OER) catalysts mainly suffers from sluggish kinetics and high overpotential except for the Ir and Ru‐based systems. However, the high cost and vulnerability of the Ir and Ru metals are the main hostiles to use them for marketization. Herein, a high‐performance OER electrocatalyst consisting of NiCo alloy nanoparticles supported on high surface area N‐doped porous graphene (NiCo/pNGr(75:25)) is reported. The importance of the doped‐N for achieving the uniform dispersion‐cum‐effective interaction of the size controlled NiCo alloy nanoparticles has been explicitly investigated by transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, Raman, density functional theory (DFT) calculations, etc. The electrochemical analysis of NiCo/pNGr(75:25) shows an overpotential of ≈260 mV at 10 mA cm−2 with a smaller Tafel slope of ≈87 mV dec−1 and long catalytic durability. DFT calculations are done to check the interaction between the NiCo alloy nanoparticles and the defective sites of pNGr and also with the doped‐N, which could be attained for maintaining long catalytic durability. Furthermore, NiCo/pNGr(75:25) is used as an OER catalyst to fabricate an electrolyzer, which works at very low potential of 1.5 V in 1 m KOH. 相似文献