Gas Sensing of NiO‐SCCNT Core–Shell Heterostructures: Optimization by Radial Modulation of the Hole‐Accumulation Layer

Hierarchical core–shell (C–S) heterostructures composed of a NiO shell deposited onto stacked‐cup carbon nanotubes (SCCNTs) are synthesized by atomic layer deposition (ALD). A film of NiO particles (0.80–21.8 nm in thickness) is uniformly deposited onto the inner and outer walls of the SCCNTs. The electrical resistance of the samples is found to increase of many orders of magnitude with the increasing of the NiO thickness. The response of NiO–SCCNT sensors toward low concentrations of acetone and ethanol at 200 °C is studied. The sensing mechanism is based on the modulation of the hole‐accumulation region in the NiO shell layer upon chemisorption of the reducing gas molecules. The electrical conduction mechanism is further studied by the incorporation of an Al₂O₃ dielectric layer at NiO and SCCNT interfaces. The investigations on NiO–Al₂O₃–SCCNT, Al₂O₃–SCCNT, and NiO–SCCNT coaxial heterostructures reveal that the sensing mechanism is strictly related to the NiO shell layer. The remarkable performance of the NiO–SCCNT sensors toward acetone and ethanol benefits from the conformal coating by ALD, large surface area of the SCCNTs, and the optimized p‐NiO shell layer thickness followed by the radial modulation of the space‐charge region.     

用于CO2排放源监测的近红外光参量振荡系统

基于CO2的近红外吸收光谱特征,提出了一种可用于CO2排放源监测的光参量振荡(OPO)和放大(OPA)系统,该系统由输入OPO的激光双种子源、OPO和OPA、带窄线宽激光种子源脉冲Nd∶YAG基频激光器、高精度和频率稳定的双通道波长计等组成,可交替输出1.572 μm的双波长激光束.系统经初步调试后,泵浦脉冲能量为326mJ时获得近25％的转换效率,脉冲能量近80mJ,满足地基差分吸收激光雷达测量对流层CO2浓度廓线的需要.     

催化裂解无水乙醇制备纳米碳管

以N2作载气,二茂铁作催化剂,高温催化裂解无水乙醇溶液,制备出纯度较高,管径分布在30 nm~40 nm的纳米碳管。利用SEM和TEM对纳米碳管的结构进行了表征。根据纳米碳管的微观形貌,给出了一种可能的生长机制。该制备过程不使用任何有毒有害物质,工艺简单,这对实现纳米碳管的规模生产具有重要意义。     

双电层电容器高比表面积活性炭的研究

以石油焦为原料,KOH和NaOH为活化剂制取双电层电容器用高比表面积活性炭电极材料。考察了活化剂的种类及其与石油焦配比对活性炭比电容的影响,并对KOH和NaOH的混和物在活化过程中金属K和Na的协同作用进行了初步探讨。研究结果表明控制适宜的活化工艺条件可制得比电容高达52.60 F/g的高比表面积活性炭,用它组装成的双电层电容器具有良好的充放电性能。     

BBO晶体Ⅰ型非共线相位匹配参量放大研究

理论研究了BBO晶体在Ⅰ型相位匹配下非共线情况时的激光参量放大特性。研究结果表明 ,对于一定波长的抽运光 ,存在一定的非共线入射角对应一定波长的信号光 ,使在较高的激光增益下增益带宽最大 ,同时温度的调谐也对增益谱的形状有部分影响。这对于短激光脉冲的激光参量放大的优化具有重要意义。     

类金刚石薄膜的Raman光谱分析及红外光谱特性

用酒精和氢气的混合气体为工作气体 ,在不同的酒精浓度下 (1 0 % ,1 5% ,2 0 % )下利用微波等离子体化学气相沉积法在较低温度下 (450～ 50 0℃ )以单晶硅为衬底制备出类金刚石薄膜样品。 Raman光谱分析了酒精浓度对薄膜中金刚石成份的含量的影响。红外光谱分析表明薄膜的红外光透过率与薄膜的表面形貌、薄膜结构有关。酒精浓度为 1 0 %时得到的金刚石薄膜的红外光透过率最高 ,达到 62～ 72 % ,同时透过率曲线因薄膜干涉而引起的振荡也最为显著。     

热沉尺寸对半导体激光器有源区温度的影响

半导体激光器随着输出功率的提高在各领域的应用日益广泛,但芯片温度升高引起的功率饱和问题仍然是目前研究的重点之一。利用ANSYS软件对工作波长为808nm的单芯片半导体激光器的芯片有源区温度与封装热沉尺寸的关系进行了稳态热分析,模拟得出不同热沉参数条件下封装激光器芯片有源区温度的变化曲线,并提出一种散热较好的结构方案。     

硼，氮共掺碳纳米管的第一性原理研究

小管径单壁碳纳米管因为曲率效应和局部效应的影响,有着不同的电学性能。传统的密度泛函计算并不能完全处理这些影响因素,但是杂化泛函计算却可以。我们通过HSE杂化泛函计算研究了（2,3）碳纳米管共掺杂不同浓度的氮,硼原子,发现了能隙和一些其他性质均随着掺杂成分的改变而发生振荡变化。我们的研究阐明了对小管径纳米管性质的认识。这对设计新型纳米电子设备有潜在作用。     

Embedding RhPx in N,P Co‐Doped Carbon Nanoshells Through Synergetic Phosphorization and Pyrolysis for Efficient Hydrogen Evolution

Rational design and controllable synthesis of well‐defined nanostructures with high stability and Pt‐like activity for hydrogen evolution reaction (HER) are critical for renewable energy conversion. Herein, a unique pyrolysis strategy is demonstrated for the synthesis of RhP_x nanoparticles (NPs) in N, P co‐doped thin carbon nanoshells (RhP_x@NPC nanoshells) that display high electrocatalytic activity and stability over a wide pH range. This strategy involves simultaneous phosphorization and pyrolysis processes that can produce highly‐dispersed RhP_x NPs within N, P co‐doped carbon nanoshells and at the same time induce thinning of carbon nanoshells from inside out. The resulting RhP_x@NPC nanoshells not only possess Pt‐like activity for HER with low overpotentials to achieve 10 mA cm^?2 (22 mV in 0.5 m H₂SO₄, 69 mV in 1.0 m KOH, and 38 mV in 1.0 m phosphate buffered saline (PBS)) but also provide long‐term durability in a wide pH range. The remarkable HER performance of RhP_x@NPC nanoshells is ascribed to the high surface area, abundant mesoporosity, strong catalyst–support interaction, ultrathin carbon encapsulation, and N, P co‐doping. This work provides an effective strategy for designing heterostructured electrocatalysts with high catalytic activity and stability desired for reactions that may occur under harsh conditions.