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排序方式: 共有159条查询结果,搜索用时 78 毫秒
131.
132.
Dr. Yanan Tang Dr. Weiguang Chen Dr. Bingjie Wu Dr. Gao Zhao Prof. Zhiyong Liu Dr. Yi Li Prof. Xianqi Dai 《Chemphyschem》2019,20(19):2506-2517
Based on density functional theory (DFT) calculations, the formation geometries, stability and catalytic properties of single-atom iron anchored on xN-doped graphene (xN-graphene-Fe, x=1, 2, 3) sheet are systemically investigated. It is found that the different kinds and numbers of gas reactants can effectively regulate the electronic structure and magnetic properties of the 3 N-graphene-Fe system. For NO and CO oxidation reactions, the coadsorption configurations of NO/O2 and CO/O2 molecules on a reactive substrate as the initial state are comparably analyzed. The NO oxidation reactions through the Langmuir–Hinshelwood (LH) and Eley-Rideal (ER) mechanisms have relatively smaller energy barriers than those of the CO oxidation processes. In comparison, the preadsorbed 2NO reacting with 2CO molecules (2NO+2CO→2CO2+N2) through ER reactions (<0.4 eV) are energetically more favorable processes. These results can provide beneficial references for theoretical studies on NO and CO oxidation and designing graphene-based catalyst for toxic gas removal. 相似文献
133.
在5 % OV7/Chromosorb WAW DMCS的色谱柱上分离和测定水田除草剂2(2萘氧基) 丙酰替苯胺( 俗称萘丙胺) 。以苯二甲酸二异辛酯为内标物时,萘丙胺与内标物等之间均获得较好的分离。而且,萘丙胺的相对质量校正因子相当稳定,fW.A=0 .978 ±0.005(α= 0.05,n= 6) 。该方法具有操作简便、快速、准确度和精密度较好,对同一试样的多次平行独立测定其标准偏差≤0.90,变异系数≤1 .18 % 。该方法完全适合于水田除草剂萘丙胺的生产控制分析和产品质量的检验。 相似文献
134.
以三醛基间苯三酚(TFP)和溴化乙锭(EB)为单体, 在溶剂热条件下合成了一种二维β-酮烯胺类阳离子型共价有机框架(COF)材料. 所得TFP-EB COF呈现出良好的结晶度、 高的比表面积和丰富的溴化乙锭单元, 故可将其应用于水中非甾体抗炎药(NSAIDs)的去除.阳离子TFP-EB COF对双氯芬酸钠(DCF-S)和对氨基水杨酸钠(PAS-S)两种非甾体抗炎药表现出高的吸附能力和快的吸附动力学, 其饱和吸附容量分别可达350.4和145.3 mg/g. 而采用TFP与4,4'-二氨基联苯(BND)在类似条件下合成的中性TFP-BND COF则表现出较差的吸附性能, 其对DCF-S和PAS-S的饱和吸附容量分别仅有59.7和13.6 mg/g. TFP-EB COF的吸附性能比TFP-BND COF更优异, 这主要归因于TFP-EB COF孔道中存在的大量阳离子EB单元与NSAIDs中的羧基间存在强烈的静电作用. 此外, 竞争离子干扰和循环再生实验表明阳离子型TFP-EB COF在NSAIDs污染物的去除方面具有良好的应用前景. 相似文献
135.
136.
Helmholtz共振结构的声屏障在控制道路交通噪声方面具有潜在的应用前景。为有效提高特定频段的噪声控制,本文设计了一种主腔连接4个副腔的Helmholtz复合共振腔结构。首先,利用有限元法对共振腔模型进行计算分析,得出共振腔的禁带结构和声传播损耗曲线;其次,利用声-电类比法建立了Helmholtz共振腔的等效电路,并对带隙的产生机理进行分析;最后,讨论了结构参数对Helmholtz共振腔带隙的影响,并分析这些参数对第一带隙下限的影响机理。结果表明:声波在Helmholtz共振腔单元间同时存在相互作用和腔内谐振效应,能在晶格常数为60 mm的情况下获得范围为432.43~663.98 Hz的第一带隙,比单、双开口圆环带隙起始频率更低,且大部分频率范围的隔声量达到10 dB以上,最大隔声量超过90 dB,表现出良好的中频隔声特性;等效电路模型与有限元法的计算值的最大误差不超过10%且平均误差低于5%,建立的等效模型是合理的;结构参数对于带隙有较大影响,主要是通过影响共振腔内部气体的体积从而影响带隙。 相似文献
137.
基于1.6μm甲烷气体吸收线的半导体激光器频率稳定性分析 总被引:1,自引:0,他引:1
利用波长调制技术以及数字PI控制器将外腔二极管激光器(ECDL)稳定到1.6 μm处的甲烷气体吸收线上.稳定后的激光频率波动小于5.6 MHz,相对于自由运转时的160 MHz有了很大提高, 而误差信号的Allan方差均方根(即稳定度)在平均积分时间为64 s时达到最小值1.66×10-11.从理论上定性分析了频率稳定度受到的各种限制因素,最后得出本实验中频率稳定度主要受频率调制和探测器噪声限制的结论,同时给出了提高频率稳定度的方法.被稳定的激光器主要用于为甲烷气体浓度监测提供频率参考. 相似文献
138.
Dr. Yanan Tang Dr. Weiguang Chen Dr. Gao Zhao Dr. Da Teng Dr. Yingqi Cui Dr. Zhaohan Li Dr. Zhen Feng Prof. Xianqi Dai 《Chemphyschem》2021,22(6):606-618
Noble metal single-atom catalysts (NM-SACs) anchored at novel graphene-like supports has attracted enormous interests. Gas sensitivity, catalytic activity, and d-band centers of single NM (Pt and Pd) atoms at graphenylene (graphenylene-NM) are investigated using first-principle calculations. The adsorption geometries of gas reactants on graphenylene-NM sheets are analyzed. It is found that the adsorption energies of reactant species on graphenylene-Pt are larger than those on graphenylene-Pd, because the d-band center of the Pt atom is closeser to the Fermi level. The NO and CO oxidation reactions on graphenylene-NM are investigated via four catalytic mechanisms, including Langmuir-Hinshelwood (LH), Eley-Rideal (ER), New ER (NER), and termolecular ER (TER). The results show that the NO and CO oxidations via LH and TER mechanisms can occur owing to the relatively small energy barriers. Moreover, the interaction of 2NO+2CO via ER mechanism is the energetically more favorable reaction. Although the NO oxidation via the NER mechanism has rather low energy barriers, the reaction is unlikely to occur due to the low adsorption energy of O2 compared with CO and NO. This research may provide guidance for exploring the catalytic performance of SACs on graphene-like materials to remove toxic gas molecules. 相似文献
139.
Achieving Simultaneous CO2 and H2S Conversion via a Coupled Solar‐Driven Electrochemical Approach on Non‐Precious‐Metal Catalysts
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Dr. Weiguang Ma Hong Wang Dr. Wei Yu Xiaomei Wang Zhiqiang Xu Prof. Xu Zong Prof. Can Li 《Angewandte Chemie (International ed. in English)》2018,57(13):3473-3477
Carbon dioxide (CO2) and hydrogen sulfide (H2S) are generally concomitant with methane (CH4) in natural gas and traditionally deemed useless or even harmful. Developing strategies that can simultaneously convert both CO2 and H2S into value‐added products is attractive; however it has not received enough attention. A solar‐driven electrochemical process is demonstrated using graphene‐encapsulated zinc oxide catalyst for CO2 reduction and graphene catalyst for H2S oxidation mediated by EDTA‐Fe2+/EDTA‐Fe3+ redox couples. The as‐prepared solar‐driven electrochemical system can realize the simultaneous conversion of CO2 and H2S into carbon monoxide and elemental sulfur at near neutral conditions with high stability and selectivity. This conceptually provides an alternative avenue for the purification of natural gas with added economic and environmental benefits. 相似文献
140.
Dr. Bingqing Zhang Dr. Shengyang Wang Dr. Wenjun Fan Dr. Weiguang Ma Dr. Zhenxing Liang Prof. Jingying Shi Prof. Shijun Liao Prof. Can Li 《Angewandte Chemie (International ed. in English)》2016,55(47):14748-14751
The oxygen reduction reaction (ORR) is a key step in H2–O2 fuel cells, which, however, suffers from slow kinetics even for state‐of‐the‐art catalysts. In this work, by making use of photocatalysis, the ORR was significantly accelerated with a polymer semiconductor (polyterthiophene). The onset potential underwent a positive shift from 0.66 to 1.34 V, and the current was enhanced by a factor of 44 at 0.6 V. The improvement was further confirmed in a proof‐of‐concept light‐driven H2–O2 fuel cell, in which the open circuit voltage (Voc) increased from 0.64 to 1.18 V, and the short circuit current (Jsc) was doubled. This novel tandem structure combining a polymer solar cell and a fuel cell enables the simultaneous utilization of photo‐ and electrochemical energy, showing promising potential for applications in energy conversion and storage. 相似文献