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1.
掺杂SnO2氨气敏感材料研究 总被引：3，自引：0，他引：3
通过主体材料ＳｎＯ２掺入多处掺杂剂对气敏特性影响的研究，得到了对氨气（ＮＨ３）敏感的材料的较佳配方，该敏感材料作成的气敏传感器对氨气具有较高的灵敏度和较好的稳定性。 相似文献
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Yu Wu Lei Jiao Xin Luo Weiqing Xu Xiaoqian Wei Hengjia Wang Hongye Yan Wenling Gu Bo Z. Xu Dan Du Yuehe Lin Chengzhou Zhu 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(43)
Single‐atom catalysts (SACs) have attracted extensive attention in the catalysis field because of their remarkable catalytic activity, gratifying stability, excellent selectivity, and 100% atom utilization. With atomically dispersed metal active sites, Fe‐N‐C SACs can mimic oxidase by activating O2 into reactive oxygen species, O2?? radicals. Taking advantages of this property, single‐atom nanozymes (SAzymes) can become a great impetus to develop novel biosensors. Herein, the performance of Fe‐N‐C SACs as oxidase‐like nanozymes is explored. Besides, the Fe‐N‐C SAzymes are applied in biosensor areas to evaluate the activity of acetylcholinesterase based on the inhibition toward nanozyme activity by thiols. Moreover, this SAzymes‐based biosensor is further used for monitoring the amounts of organophosphorus compounds. 相似文献
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Yuanyuan Ma Tong Yang Haiyuan Zou Wenjie Zang Zongkui Kou Lu Mao Yuanping Feng Lei Shen Stephen J. Pennycook Lele Duan Xu Li John Wang 《Advanced materials (Deerfield Beach, Fla.)》2020,32(33):2002177
Previous research of molybdenum-based electrocatalysts for nitrogen reduction reaction (NRR) has been largely considered on either isolated Mo single atoms (MoSAs) or Mo carbide particles (e.g., Mo2C) separately, while an integrated synergy (MoSAs-Mo2C) of the two has never been considered. The theoretical calculations show that the Mo single atoms and Mo2C nanoparticles exhibit, respectively, different catalytic hydrogen evolution reaction and NRR selectivity. Therefore, a new role-playing synergistic mechanism can be well enabled for the multistep NRR, when the two are combined on the same N-doped carbon nanotubes (NCNTs). This hypothesis is confirmed experimentally, where the MoSAs-Mo2C assembled on NCNTs (MoSAs-Mo2C/NCNTs) yields an ammonia formation rate of 16.1 µg h−1 cmcat−2 at −0.25 V versus reversible hydrogen electrode, which is about four times that by the Mo2C alone (Mo2C/NCNTs) and 4.5 times that by the MoSAs alone (MoSAs/NCNTs). Moreover, the Faradic efficiency of the MoSAs-Mo2C/NCNTs is raised up to twofold and sevenfold of the Mo2C/NCNTs and MoSAs/NCNTs, respectively. The MoSAs-Mo2C/NCNTs also demonstrate outstanding stability by the almost unchanged catalytic performance over 10 h of the chronoamperometric test. The present study provides a promising new prototype of synchronizing the selectivity and activity for the multistep catalytic reactions. 相似文献
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Heon Jun Jeong Wanhyuk Chang Beum Geun Seo Yun Sung Choi Keun Hee Kim Dong Hwan Kim Joon Hyung Shim 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(22):2208149
This study reports the performance and durability of a protonic ceramic fuel cells (PCFCs) in an ammonia fuel injection environment. The low ammonia decomposition rate in PCFCs with lower operating temperatures is improved relative to that of solid oxide fuel cells by treatment with a catalyst. By treating the anode of the PCFCs with a palladium (Pd) catalyst at 500 °C under ammonia fuel injection, the performance (peak power density of 340 mW cm−2 at 500 °C) is approximately two-fold higher than that of the bare sample not treated with Pd. Pd catalysts are deposited through an atomic layer deposition post-treatment process on the anode surface, in which nickel oxide (NiO) and BaZr0.2Ce0.6Y0.1Yb0.1O3–δ (BZCYYb) are mixed, and Pd can penetrate the anode surface and porous interior. Impedance analysis confirmed that Pd increased the current collection and significantly reduced the polarization resistance, particularly in the low-temperature region (≈500 °C), thereby improving the performance. Furthermore, stability tests showed that superior durability is achieved compared with that of the bare sample. Based on these results, the method presented herein is expected to represent a promising solution for securing high-performance and stable PCFCs based on ammonia injection. 相似文献
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Zhihao Pei;Huabin Zhang;Yan Guo;Deyan Luan;Xiaojun Gu;Xiong Wen Lou; 《Advanced materials (Deerfield Beach, Fla.)》2024,36(17):2306047
Manipulating the coordination environment and electron distribution for heterogeneous catalysts at the atomic level is an effective strategy to improve electrocatalytic performance but remains challenging. Herein, atomically dispersed Fe and Co anchored on nitrogen, phosphorus co-doped carbon hollow nanorod structures (FeCo-NPC) are rationally designed and synthesized. The as-prepared FeCo-NPC catalyst exhibits significantly boosted electrocatalytic kinetics and greatly upshifts the half-wave potential for the oxygen reduction reaction. Furthermore, when utilized as the cathode, the FeCo-NPC catalyst also displays excellent zinc-air battery performance. Experimental and theoretical results demonstrate that the introduction of single Co atoms with Co-N/P coordination around isolated Fe atoms induces asymmetric electron distribution, resulting in the suitable adsorption/desorption ability for oxygen intermediates and the optimized reaction barrier, thereby improving the electrocatalytic activity. 相似文献
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Y是稀土铝合金中常用的添加元素,Y和Al可以形成五种不同的化合物,Y-Al化合物对稀土铝合金的性能有重要的影响.基于固体与分子经验电子理论(EET)和键距差方法(BLD),计算了五种Y-Al化合物的价电子结构和化学键键能,从价电子结构层次探讨了五种Y-Al化合物对稀土铝合金强度、塑性和高温稳定性的影响.计算结果表明,五种Y-Al化合物对铝合金的室温强度都有较好的增强作用;YAl3的塑性最好但稳定性极差;Y3Al2和Y2Al的脆性高,对铝合金的塑、韧性有严重的削弱;YAl2的强度和塑性居中,但稳定性最强,熔点高,对铝合金的室温强度、高温稳定性和高温强度都有显著的贡献.因此,在稀土铝合金的制备中,应促进YAl2相的生成. 相似文献
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球差校正扫描透射电子显微镜（STEM）因其原子级的空间分辨率和元素解析能力,在纳米功能材料的结构和成分分析中得到广泛使用。扫描透射电子显微镜高角环形暗场像技术（STEM-HAADF）凭借独特的原子序数衬度（Z衬度）和电子通道效应,在负载型纳米催化剂的结构研究中有着显著优势。通过STEM-HAADF成像,研究人员不仅可以直接观测到单个贵金属原子在较轻的载体上的实空间分布,还可以实现对载体表面上不同的负载贵金属物种的统计分析,这为近十年兴起的单原子催化剂研究提供了最重要的结构分析支持。相对于STEM-HAADF成像,基于STEM的X射线能谱（EDS）和电子能量损失谱（EELS）的谱学分析技术则能够在纳米尺度乃至原子尺度提供直接的化学成分或化学价态信息。成像和谱学的结合能够更准确地确定负载的金属原子在基底上的空间构型。进一步将原位电镜技术引入扫描透射电子显微镜内,则可以在时间尺度上探究催化剂在接近工作环境下的结构演化,从而更全面地揭示催化剂化学活性的结构起源与失效机制。本文结合近几年的部分代表性研究成果,简要介绍球差校正STEM技术在原子级分散负载催化剂研究中的应用,并对其在该研究领域的进一步发展进行了展望。 相似文献
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Effect of interface microstructure on the bond strength of the diffusion welded joints between titanium and stainless steel 总被引：2，自引：0，他引：2
Diffusion bonding between commercially pure titanium and 304 stainless steel was carried out at a temperature of 950 °C for 30–120 min under uniaxial load in a vacuum. The diffusion bonds were characterized by optical and scanning electron microscopy. The diffusion zone contained different reaction bands and their chemical composition was determined using energy dispersive X-ray spectroscopy. The concentration of chemical species indicated the presence of σ, λ, χ, FeTi, β-Ti and Fe2Ti4O phases in the reaction zone and their existence was confirmed by X-ray diffraction. A maximum bond strength of 71% of that of titanium along with 5.8% ductility were obtained for the diffusion couple processed for 30 min due to formation of finer size intermetallics. A rise in joining time increases void generation and growth of intermetallic compounds, which are responsible for a drastic fall in the strength value. 相似文献
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抗电子发射钼栅极的性能分析 总被引：4，自引：1，他引：4
利用真空离子沉积技术在钼栅极的表面分别镀上一层Ｃ膜Ａｌ膜ＡｌＴｌＺｒ合金膜,对镀膜后的样品进行寿命试验。用ＳＥＭ和ＸＲＤ分析技术镀膜样品受了阴极活性蒸发物Ｂａ污染前,污染后进行了对比研究,实验结果表明,逸出功较低的Ａｌ在受取Ｂａ污染后,能够生成金属间化合物,从而能够有效地抑制栅极发射,而沉积的Ｃ膜在受到污染后,逐渐被消耗而失去作用;在Ａｌ中加逸出功较高的ＴｉＺｒ合金后,破坏了金属间化合物的生成,并 相似文献
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目的 解决TiNi/TC4异种金属的焊接问题,扩大此2种金属的结合应用.方法 选用3 mm×40 mm×0.5 mm的FeCoCrNiMn高熵合金薄片作为中间层,采用电子束焊接方法焊接TiNi/TC4.对形成的接头进行宏观分析,采用电子显微镜以及X射线衍射仪对其微观组织进行表征;通过拉伸和硬度测试,分析该接头的力学性能.结果 接头宏观成形存在裂纹缺陷,观察微观组织发现,在焊接接头中只形成了AlTi3相和Ni0.35Al0.30Ti0.35相,没有形成Ti2Ni相.接头的抗拉强度为81.8 MPa,伸长率为4.38％,平均显微硬度为HV661,断口呈脆性断裂特征.结论 将高熵合金作为中间层焊接TiNi/TC4是一种有效的方法,可以成功实现异种金属的焊接,中间层的存在可以有效调控焊缝中的析出相种类. 相似文献
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Chao Gao Shuangming Chen Ying Wang Jiawen Wang Xusheng Zheng Junfa Zhu Li Song Wenkai Zhang Yujie Xiong 《Advanced materials (Deerfield Beach, Fla.)》2018,30(13)
Visible‐light‐driven conversion of CO2 into chemical fuels is an intriguing approach to address the energy and environmental challenges. In principle, light harvesting and catalytic reactions can be both optimized by combining the merits of homogeneous and heterogeneous photocatalysts; however, the efficiency of charge transfer between light absorbers and catalytic sites is often too low to limit the overall photocatalytic performance. In this communication, it is reported that the single‐atom Co sites coordinated on the partially oxidized graphene nanosheets can serve as a highly active and durable heterogeneous catalyst for CO2 conversion, wherein the graphene bridges homogeneous light absorbers with single‐atom catalytic sites for the efficient transfer of photoexcited electrons. As a result, the turnover number for CO production reaches a high value of 678 with an unprecedented turnover frequency of 3.77 min?1, superior to those obtained with the state‐of‐the‐art heterogeneous photocatalysts. This work provides fresh insights into the design of catalytic sites toward photocatalytic CO2 conversion from the angle of single‐atom catalysis and highlights the role of charge kinetics in bridging the gap between heterogeneous and homogeneous photocatalysts. 相似文献
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High magnetic fields up to 10 T are applied to thermal chemical vapor deposition (CVD) for carbon nanotube synthesis in order to control the nanotube morphology. Although changes of the nanotube morphology in the presence of magnetic field were not obviously discernible in the SEM images, an increase in the onion-like nano-carbons due to magnetic field was observed by TEM. It suggests that the magnetic field influences formation processes of nano-carbons including carbon nanotubes, via magnetic effects on metal catalysts. 相似文献
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Jianli Liang;Huabin Zhang;Qianqian Song;Zheyang Liu;Jing Xia;Binhang Yan;Xiangmin Meng;Zhifeng Jiang;Xiong Wen Lou;Chun-Sing Lee; 《Advanced materials (Deerfield Beach, Fla.)》2024,36(1):2303287
To alleviate the greenhouse effect and address the related energy crisis, solar-driven reduction of carbon dioxide (CO2) to value-added products is considered as a sustainable strategy. However, the insufficient separation and rapid recombination of photogenerated charge carriers during photocatalysis greatly limit their reduction efficiency and practical application potential. Here, isolated Cobalt (Co) atoms are successfully decorated into oxygen-doped boron nitride (BN) via an in situ pyrolysis method, achieving greatly improved catalytic activity and selectivity to the carbon monoxide (CO) product. X-ray absorption fine spectroscopy demonstrates that the isolated Co atoms are stabilized by the O and N atoms with an unsaturated CoO2N1 configuration. Further experimental investigation and theoretical simulations confirm that the decorated Co atoms not only work as the real active center during the CO2 reduction process, but also perform as the electron pump to promote the electron/hole separation and transfer, resulting in greatly accelerated reaction kinetics and improved activity. In addition, the CoO2N1 coordination geometry is favorable to the conversion from *CO2 to *COOH, which shall be considered as a selectivity-determining step for the evolution of the CO products. The surface modulation strategy at the atomic level opens a new avenue for regulating the reaction kinetics for photocatalytic CO2 reduction. 相似文献
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成功地合成了一种耐温等级高,可溶解的新型聚醚酮－多苯基取代联苯型聚醚酮,其玻璃化温度为２６５℃,５％热失重温度高于５００℃,易溶于氯信,二甲基乙酰胺等多种极性非质子有机溶剂,用红外,核磁等手段对该新型聚醚酮的结构进行了表征。 相似文献
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PZT陶瓷粉体的水热合成 总被引：1，自引：0，他引：1
利用水热法合成了单相、立方体形貌且平均颗粒尺寸在1 μm的锆钛酸铅(PZT)陶瓷粉体. 研究了碱度、反应时间对最终产物的影响, 着重研究了不同碱度下Pb缺失的补偿问题. 结果表明: 碱度对最终PZT产物A位Pb离子的固溶程度有着重要的影响. 碱度越高, A位缺失的Pb离子就越多. 原料中适当的Pb过量能够有效补偿Pb离子的缺失, 碱度越高, 所需添加的Pb离子的过量程度也就越高. 但过多的Pb离子加入量会导致最终产物中出现第二相. 相似文献
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Kuang-Kuo Wang 《Thin solid films》2010,518(23):6945-1386
The orientation relationships and interfaces of δ-AuSn with the Au (001), (110) and (111) surfaces have been studied with transmission electron microscopy. Au was evaporated onto the NaCl (001), (011) and (111) surfaces to form epitaxial Au thin films and Sn was evaporated onto the Au films to form δ-AuSn. Two types of orientation relationships have been found: (1) δ//(001)Au, (0001)δ//(110)Au, and δ//Au, which was found on the δ/(001)Au interface and the δ/Au interfaces; and (2) δ//Au, (0001)δ//(110)Au, and δ//Au, which was found on the δ/Au interface. The interfaces are analyzed by the structures of the surfaces and the orientation relationships. The nucleation of δ-AuSn on these interfaces is also discussed. 相似文献
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Eamonn Murphy Baiyu Sun Martina Rüscher Yuanchao Liu Wenjie Zang Shengyuan Guo Yu-Han Chen Uta Hejral Ying Huang Alvin Ly Iryna V. Zenyuk Xiaoqing Pan Janis Timoshenko Beatriz Roldán Cuenya Erik D. Spoerke Plamen Atanassov 《Advanced materials (Deerfield Beach, Fla.)》2024,36(27):2401133
The electrochemical reduction of nitrates (NO3−) enables a pathway for the carbon neutral synthesis of ammonia (NH3), via the nitrate reduction reaction (NO3RR), which has been demonstrated at high selectivity. However, to make NH3 synthesis cost-competitive with current technologies, high NH3 partial current densities (jNH3) must be achieved to reduce the levelized cost of NH3. Here, the high NO3RR activity of Fe-based materials is leveraged to synthesize a novel active particle-active support system with Fe2O3 nanoparticles supported on atomically dispersed Fe–N–C. The optimized 3×Fe2O3/Fe–N–C catalyst demonstrates an ultrahigh NO3RR activity, reaching a maximum jNH3 of 1.95 A cm−2 at a Faradaic efficiency (FE) for NH3 of 100% and an NH3 yield rate over 9 mmol hr−1 cm−2. Operando XANES and post-mortem XPS reveal the importance of a pre-reduction activation step, reducing the surface Fe2O3 (Fe3+) to highly active Fe0 sites, which are maintained during electrolysis. Durability studies demonstrate the robustness of both the Fe2O3 particles and Fe–Nx sites at highly cathodic potentials, maintaining a current of −1.3 A cm−2 over 24 hours. This work exhibits an effective and durable active particle-active support system enhancing the performance of the NO3RR, enabling industrially relevant current densities and near 100% selectivity. 相似文献