The surface reconstruction of the Fe catalyst films due to high temperature processing in hydrogen prior to nanotube nucleation and its effect on the growth morphologies of partially filled carbon nanotubes (CNTs) synthesized using atmospheric pressure chemical vapor deposition (APCVD) of propane was investigated. Results show that pre-heating of the catalyst film deeply influences the particle size distribution, which governs the growth morphologies of the corresponding CNTs. The distribution of the catalyst particles over the Si substrate was analyzed before and after the heat treatment by atomic force microscopy (AFM) which reveals that heat treatment causes clusters of catalyst to coalesce and form macroscopic islands. The X-ray diffraction (XRD) pattern of the grown material indicates that they are graphitic in nature. Scanning electron microscopy (SEM) analysis suggested that the growth density strongly depends on the pre heat treatment of the Fe catalyst film. Multiwalled CNTs with partial catalyst filling were observed via high-resolution transmission electron microscopy (HRTEM) measurements. The degree of graphitization of the CNTs also depends on the pre heating as demonstrated by Raman analysis. A simple model for the growth of partially catalyst filled nanotubes is proposed.
Apically Dominant Mechanism for Improving Catalytic Activities of N-Doped Carbon Nanotube Arrays in Rechargeable Zinc-Air Battery
锌-空气电池（ZAB）中的氧还原（ORR）和析氧反应（OER）需要高效、成本有效且稳定的电催化剂作为传统的高成本、不一致稳定且低毒抗性的铂族金属（PGM）催化剂的替代物。虽然，氮掺杂的碳纳米管（NCNT）阵列已经开发了近几十年来，通过各种先进的技术，现在能够有效地催化ORR，其欠发达的双功能特性，疏水表面，和有害的制备策略被发现限制了实际的大规模商业化的有效的可充电ZAB。在这里，我们已经证明了三维（3D）镍泡沫支撑的NCNT阵列的制造，其中CoNi纳米颗粒（NP）封装在顶端域（表示为CoNi@NCNT/NF）内，其对ORR（相对于RHE的起始电位为0.97 V）和OER（在10 mA cm $^{-2}$下相对于RHE的过电位为1.54 V）表现出优异的双功能催化性能。我们进一步研究了这种CoNi@NCNT/NF材料用作可再充电ZAB纽扣电池和袋式电池系统的空气电极的实用性。ZAB纽扣电池的峰值功率密度为108 mW cm $^{-2}$，能量密度为845 Wh kg $_{Zn}^{-1}$，在环境条件下可充电28小时，超过了PGM催化剂和领先的非PGM电催化剂的性能。此外，密度泛函理论（DFT）计算显示，CoNi@NCNT/NF电极的ORR和OER催化性能主要来自于封装在NCNT的顶端主导端内的CoNi NP的d轨道。
Lithography-free control of the position of single walled carbon nanotubes on a substrate by focused ion beam induced deposition of catalyst and chemical vapor deposition
Optimization for growth condition of ultrathin hexagonal boron nitride on dielectric substrates via LPCVD
Gazi University（加齐大学）；Turkish Energy, Nuclear and Mineral Research Agency (TENMAK) Boron Research Institute（土耳其能源、核和矿物研究署硼研究所）；Sivas University of Science and Technology（锡瓦斯科技大学）；Niğde Ömer Halisdemir University（尼代奥默尔哈利斯德米尔大学）
