Characterization of TiO2 Nanoparticle’s Morphology and its Influence on the Hydrogen Sorption Kinetics of MgH2

TiO2 nanorods present good performance as catalysts in the sorption behavior of magnesium hydride. In the present study, the morphology of TiO2 nanorods produced from titanate nanotubes heat-treated at 550 °C (NR550), 650 °C (NR650) and 750 °C (NR750) was characterized and their catalytic role on the sorption kinetics of MgH2 was evaluated. For this, ball-milled MgH2-TiO2 nanocomposites with 5 wt% of additives were prepared and the materials were characterized by X-ray diffraction (XRD), BET surface area and Transmission Electron Microscopy (TEM). The hydrogen sorption kinetics of the composites were evaluated in a Sievert’s apparatus at 350 °C. The results indicated that NR550 and NR650 consisted of a mixture of nanorods and nanoparticles and NR750 of coarser nanoparticles of TiO2-anatase with a small amount of rutile. Composites with NR750 and NR550 presented the best sorption kinetics, suggesting the positive effect of the presence of rutile and of anatase nanorods, respectively, on the sorption properties of the material.

二氧化钛纳米棒（TiO₂ nanorods）在氢化镁的吸放氢行为中作为催化剂展现出优异性能。本研究中，对以钛酸纳米管为前驱体、分别经550℃、650℃、750℃热处理制备的二氧化钛纳米棒（分别记为NR550、NR650、NR750）的形貌进行了表征，并评估了其对氢化镁（MgH₂）吸放氢动力学的催化作用。为此，本研究制备了添加5wt%该二氧化钛纳米棒添加剂的球磨型MgH₂-TiO₂纳米复合材料，采用X射线衍射（X-ray diffraction, XRD）、Brunauer-Emmett-Teller（BET）比表面积测试以及透射电子显微镜（Transmission Electron Microscopy, TEM）对所制备的材料进行了表征。采用Sievert型储氢测试仪在350℃下评估了该复合材料的吸放氢动力学性能。结果表明，NR550与NR650均为纳米棒与纳米颗粒的混合结构，而NR750则由粒径更粗的锐钛矿相二氧化钛（TiO₂-anatase）纳米颗粒与少量金红石相（rutile）组成。添加NR750与NR550的复合材料展现出最优的吸放氢动力学性能，这分别表明金红石相的存在与锐钛矿型纳米棒的存在对该材料的储氢性能具有积极的促进作用。