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141.
《Arabian Journal of Chemistry》2020,13(1):1309-1322
A series of Pb doped CeO2 nanocubes with seven different Pb loadings (2–12 mol%) were synthesized via modified hydrothermal technique. The prepared samples were characterized by XRD, XPS, FT-IR, TGA, SEM, HR-TEM, EDS and UV–Vis DRS analysis. According to XRD analysis, the crystalline structure of synthesized pure CeO2 and Pb-doped CeO2 samples are cubic structure. The ceria nanocubes showed an increase in amount of oxygen vacancies with increasing the dopant concentrations. When the doping level of Pb is 6 mol%, the optical band gap of Pb-CeO2 is smaller than that of pure CeO2 nanocubes. The HR-TEM results confirms the cubic structure of 6% Pb-CeO2 with average crystallite size of about 15 nm. The photocatalytic ability of Pb-CeO2 catalysts were studied by degrading several anionic and cationic organic pollutants like methylene blue (MB), methylene orange (MO), methylene red (MR), rhodamine B (RhB), reactive blue 160 (RB160), salicylic acid (SA), coumarin and phenol. The 6% Pb-CeO2 nanocubes shows better photocatalytic performance against anionic dyes especially for MB. To find the optimum condition for better photocatalytic performance of 6% Pb-CeO2 nanocubes, the photocatalytic process was conducted in different initial reaction conditions like reaction temperature, catalytic dosage, dye concentration and pH of the reaction solution. The stability and recyclability of 6% Pb-CeO2 photocatalyst was studied by XRD, FT-IR and EDS analysis after 5 cycles of MB degradation. The hydroxyl radical estimation and trapping experiments were conducted to observe the photocatalytic mechanism process in 6% Pb-CeO2 nanocubes. The perfect doping concentration for better organic pollutant degradation by Pb-CeO2 is found to be 6 mol% of Pb. 相似文献
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144.
The interaction of atomic oxygen with the clean Cu(100) surface has been studied by means of cluster and periodic slab models density functional theory in the present paper. The Cu(4,9,4) cluster and a three-layer slab with c(2×2) structure are used to model the perfect Cu(100) surface. Three possible adsorption sites,top, bridge and hollow site, were considered in the calculations. The predicted results show that the hollow site is the prefer site for atomic oxygen adsorbed on Cu(100) surface energetically. This is in good agreement with the experiment. The calculated binding energies are respective 2.014, 3.154 and 3.942 eV for top, bridge and hollow sites at mPW1PW91/LanL2dz level for the cluster model. The geometry of Cu(100) surface has also been optimized theoretically with various density functional methods and the results show that the prediction from the B3PW91/LanL2dz and mPW1PW91/LanL2dz reproduce the experimental observation.The frontier molecular orbitals and partial density of states analysis show that the electron transfer from the d orbital of substrate to the p orbital of the surface oxygen atom. 相似文献
145.
研究了混合稀土储氢合金中氧和氮的测定方法。针对稀土金属高温易挥发、分解的特点,选择适宜的加热温度,使用镍浴,选择高温座坩埚进行试验:选择出了合适的助熔剂的预处理方法。方法已用于实际样品。对含氧0.43%、含氮0.018%的试样,分析精密度为氧4.3%,氮5.9%,加标回收率氧为93%~104%,氮为92%~110%。 相似文献
146.
以卡维地洛药物分子为模板,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,采用紫外光引发聚合的分子印迹技术,成功制备出卡维地洛分子印迹聚合物。用热重分析、扫描电镜对聚合物进行了表征,通过Scatchard方程研究了印迹聚合物对模板分子的结合特性。结果表明,在所研究的浓度范围内,印迹聚合物存在一类等价的结合位点,并计算出印迹聚合物与模板分子的平衡离解常数为0.5642 mmol/L,最大表观吸附量为97.44μmol/g,为理论值的63.53%。对不同底物的结合实验表明,该聚合物对卡维地洛具有优良的吸附选择性。 相似文献
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The inherent periodically arranged M−NX, M−SX and M−OX units (M are usually Fe, Co, Ni, etc.) in metal–organic frameworks (MOFs) can be promising active centers in electrocatalysis. In previous studies, MOFs were usually constructed by energy-consuming hydro- or solvo-thermal reactions. Ultrasonic synthesis is a rapid and environment-friendly technique when envisaging MOFs’ industrial applications. In addition, different synthetic pathways for MOFs may lead to difference in their microstructure, resulting in different electrocatalytic performance. Nevertheless, only a handful of MOFs were successfully prepared by ultrasonic synthesis and few were applied in electrochemical catalysis. Herein, we constructed Ni/Co-catecholates (Ni/Co-CATs) synthesized by one-step ultrasonic method (250 W, 40 KHz, 25 W/L, Ultrasonic clearing machine) and compared their performance in oxygen reduction reaction (ORR) with that of Ni/Co-CATs synthesized by hydrothermal method. Ni-CAT and Co-CAT prepared by ultrasonic showed the half-wave potential of −0.196 V and −0.116 V (vs. Ag/AgCl), respectively. The potentials were more positive than those prepared by hydro-thermal method. And they showed excellent electrochemical stability in neutral solution. The latter was only 32 mV lower than that of commercial Pt/C. The improved performance in ORR was attributed to higher specific surface area and mesopore volume as well as more structural defects generated in the ultrasonic synthesis process, which could facilitate their exposure of electrocatalytic active sites and their mass transport. This work gives some perspective into cost-effective synthetic strategies of efficient MOFs-based electrocatalysts. 相似文献
149.
《Current Applied Physics》2020,20(3):456-461
Carbon-based electrocatalysts for oxygen reduction reaction (ORR), especially in anion exchange membrane fuel cells (AEMFCs), have received a lot of attention because they exhibit excellent stability and are comparable to commercial Pt/C catalysts. Currently, to maximize the catalytic activity of carbon-based electrocatalysts, there are two major strategies: heteroatom doping or exposing active edge sites. However, the approach of increasing heteroatomic dopants of active edge sites has been rarely addressed. In this study, we present a simple strategy to prepare edge-enriched graphene catalysts with an increased ratio of heteroatomic dopants suitable for ORR of AEMFCs. The catalysts were prepared under harsh oxidation conditions, followed by a simple co-doping process with boron and nitrogen. The ORR activity of the catalysts was observed to be related to an increase of edge sites with heteroatomic dopants. We believe that the edge-enriched structure leads to accelerated electron transfer with enhanced oxygen adsorption. 相似文献
150.
氟化锶/氧化钕催化剂的甲烷氧化偶联性能及其吸附氧物种的原位FTIR光谱研究龙瑞强,万惠霖,赖华龙,蔡启瑞(厦门大学化学系固体表面物理化学国家重点实验室,厦门,361005)关键词甲烷氧化偶联,氟化锶/氧化钕,吸附氧物种近年来,甲烷氧化偶联(OCM)的... 相似文献