Copper Promoted Au/ZnO-CuO Catalysts for Low Temperature Water-gas Shift Reaction

IntroductionThe water-gas shift(WGS)reaction is an impor-tant step in many important chemical processes[1].Re-cently,the renewed interest in the removal of CO bythe WGS reaction has grown significantly because of theincreasing attention to pure hydrogen p…     

三元合金Cu76Ni15Sn9的离子溅射研究

在２７ｋｅＶ Ａｒ⁺离子轰击时,用收集膜技术结合俄歇谱仪（ＡＥＳ）,研究了三元合金Cu₇₆Ni₁₅Sn₉系统的择优溅射行为。同时使用扫描电子显微镜（ＳＥＭ）与电子探针微分析（ＥＰＭＡ）．观察了靶点表面形貌变化并测定了形貌特征微区的合金组份原子的相对百分浓度。结果表明,Ｃｕ原子较Ｎｉ原子、Ｎｉ原子较Ｓｎ原子,在所测定范围（０─６０°）内择优发射。最后讨论了靶点表面形貌特征和“元素局域富集”现象对择优溅射过程的影响。 关键词：     

基于机载光电载荷图像的无人机自主循迹导引

文章研究无人机搭载视觉传感器沿指定路径自主循迹飞行,针对如何统一确定不同形状路段的目标路径点序列的问题,提出基于无人机速度在图像中投影的矢量与无人机重心指向各候选路径点矢量的最小夹角确定目标路径点的方法。首先从采集的图像中提取出的路径区域,从图像层面提取路径的中间线,将图像栅格化并分别计算各栅格里路径中间线的中心点的坐标;然后计算图像中无人机速度矢量投影与无人机重心到各路径中心点矢量的夹角,在约束范围内选取最小夹角对应的中心点作为局部目标点。设置了包含不同形状拐角的路径,检验无人机飞行过程中采集图像的处理方法和路径引导算法结合的有效性,飞行结果表明提出的方法能够满足无人机的循迹飞行要求,轨迹偏离误差小于0.1 m。     

非色散红外CO2传感器温度补偿方法研究

针对非色散红外CO₂传感器受温度影响导致测量精度低的问题,设计了单光路双通道的非色散红外CO₂传感器,提出一种BP神经网络补偿气室温度的新方法。本文分析了温度对传感器的光源、探测器以及对气体吸收系数的影响,并将BP神经网络补偿气室温度方法与其他补偿方法进行了实验对比。实验结果表明,BP神经网络补偿气室温度方法优于其他补偿方法,在测量10%～20%浓度范围内的CO₂时,最大相对误差为2.98%,重复性实验显示RSD为1.22%,为非色散红外CO₂传感器补偿温度提供借鉴意义。     

Sufficient Utilization of Mn2+/Mn3+/Mn4+ Redox in NASICON Phosphate Cathodes towards High-Energy Na-Ions Batteries

Na superionic conductor of Na₃MnTi(PO₄)₃ only containing high earth-abundance elements is regarded as one of the most promising cathodes for the applicable Na-ion batteries due to its desirable cycling stability and high safety. However, the voltage hysteresis caused by Mn²⁺ ions resided in Na⁺ vacancies has led to significant capacity loss associated with Mn reaction centers between 2.5–4.2 V. Herein, the sodium excess strategy based on charge compensation is applied to suppress the undesirable voltage hysteresis, thereby achieving sufficient utilization of the Mn²⁺/Mn³⁺ and Mn³⁺/Mn⁴⁺ redox couples. These findings indicate that the sodium excess Na_3.5MnTi_0.5Ti_0.5(PO₄)₃ cathode with Ti⁴⁺ reduction has a lowest Mn²⁺ occupation on the Na⁺ vacancies in its initial composition, which can improve the kinetics properties, finally contributing to a suppressed voltage hysteresis. Based on these findings, it is further applied the sodium excess route on a Mn-richer phosphate cathode, which enables the suppressed voltage hysteresis and more reversible capacity. Consequently, this developed Na_3.6Mn_1.15Ti_0.85(PO₄)₃ cathode achieved a high energy density over 380 Wh kg⁻¹ (based on active substance mass of cathode) in full-cell configurations, which is not only superior to most of the phosphate cathodes, but also delivers more application potential than the typical oxides cathodes for Na-ion batteries.     

An Intrinsically Nonflammable Electrolyte for Prominent-Safety Lithium Metal Batteries with High Energy Density and Cycling Stability

Nex-generation high-energy-density storage battery, assembled with lithium (Li)-metal anode and nickel-rich cathode, puts forward urgent demand for advanced electrolytes that simultaneously possess high security, wide electrochemical window, and good compatibility with electrode materials. Herein an intrinsically nonflammable electrolyte is designed by using 1 M lithium difluoro(oxalato)borate (LiDFOB) in triethyl phosphate (TEP) and N-methyl-N-propyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide [Pyr₁₃][TFSI] ionic liquid (IL) solvents. The introduction of IL can bring plentiful organic cations and anions, which provides a cation shielding effect and regulates the Li⁺ solvation structure with plentiful Li⁺-DFOB⁻ and Li⁺-TFSI⁻ complexes. The unique Li⁺ solvation structure can induce stable anion-derived electrolyte/electrode interphases, which effectively inhibit Li dendrite growth and suppress side reactions between TEP and electrodes. Therefore, the LiNi_0.9Co_0.05Mn_0.05O₂ (NCM90)/Li coin cell with this electrolyte can deliver stable cycling even under 4.5 V and 60 °C. Moreover, a Li-metal battery with thick NCM90 cathode (≈ 15 mg cm⁻²) and thin Li-metal anode (≈ 50 µm) (N/P ≈ 3), also reveals stable cycling performance under 4.4 V. And a 2.2 Ah NCM90/Li pouch cell can simultaneously possess prominent safety with stably passing the nail penetration test, and high gravimetric energy density of 470 Wh kg⁻¹ at 4.4 V.     

Simultaneous CO2 and H2O Activation via Integrated Cu Single Atom and N Vacancy Dual-Site for Enhanced CO Photo-Production

Photocatalytic conversion of CO₂ into fuels using pure water as the proton source is of immense potential in simultaneously addressing the climate-change crisis and realizing a carbon-neutral economy. Single-atom photocatalysts with tunable local atomic configurations and unique electronic properties have exhibited outstanding catalytic performance in the past decade. However, given their single-site features they are usually only amenable to activations involving single molecules. For CO₂ photoreduction entailing complex activation and dissociation process, designing multiple active sites on a photocatalyst for both CO₂ reduction and H₂O dissociation simultaneously is still a daunting challenge. Herein, it is precisely construct Cu single-atom centers and two-coordinated N vacancies as dual active sites on CN (Cu₁/N_2CV-CN). Experimental and theoretical results show that Cu single-atom centers promote CO₂ chemisorption and activation via accumulating photogenerated electrons, and the N_2CV sites enhance the dissociation of H₂O, thereby facilitating the conversion from COO* to COOH*. Benefiting from the dual-functional sites, the Cu₁/N_2CV-CN exhibits a high selectivity (98.50%) and decent CO production rate of 11.12 µmol g⁻¹ h⁻¹. An ingenious atomic-level design provides a platform for precisely integrating the modified catalyst with the deterministic identification of the electronic property during CO₂ photoreduction process.     

基于区域划分和余弦定理的DV-Hop算法改进

针对传统距离向量-跳段定位算法(Distance Vector-Hop,DV-HOP)存在的节点密度分布不均引起误差比较大的问题,根据DV-Hop算法特性,采用余弦定理,证明节点密度越大所得定位坐标越准确,使用余弦定理减少在节点密度过大时因空间角度导致节点路径曲折过多而引起的误差,同时提出一种区域划分的改进算法,减少在节点密度较小区域的误差;利用接收信号强度指示(Received Signal Strength Indicator,RSSI)对跳数进行量化分级处理,改善实际距离与计算出的距离相差过大的情况;最后采用最小二乘法估计未知节点坐标。仿真表明,所提出的算法与传统的DV-Hop算法相比,误差有一定的减少。     

声透镜指向性换能器研究

该文利用声学透镜使声波能量聚焦,实现小尺寸换能器窄波束声辐射。利用有限元方法分别建立了单凹面声透镜及双凹面声透镜仿真模型,优化了声透镜结构参数,设计并制作了双凹面声透镜指向性换能器,并在消声水池内对换能器样机和声透镜进行了性能测试。换能器样机辐射面积直径?120 mm,设置声透镜后,提高发送电压响应级4 dB,发射指向性-3 dB波束开角由76°变为约30°(@10 kHz),与仿真计算结果相符。实验结果表明,声透镜有效减小了换能器发射波束宽度,提高了换能器主瓣发送电压响应,验证了双凹面声透镜对优化换能器指向性的效果。