ARTICLE Copyright © 2012 by American Scientific Publishers All rights reserved. Printed in the United States of America Journal of Nanoengineering and Nanomanufacturing Vol. 1, pp. 1–8, 2012 (www.aspbs.com/jnan) Hydrogen Storage Properties of Heterostructured Zinc Oxide Nanostructures Rizwan Wahab 1 , Z. A. Ansari 2 , S. G. Ansari 2 , Young-Soon Kim 1 , Dong-Hyun Kim 3 , and Hyung-Shik Shin 1, * 1 Energy Materials and Surface Science Laboratory, Solar Research Center, School of Chemical Engineering, Chonbuk National University, Jeonju 561-756, Republic of Korea 2 Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India 3 Division of Materials Science and Engineering, Hanyang University, Seoul 133-791, Korea ABSTRACT Belt, rod, sheet and flower like nanostructures of zinc oxide were synthesized by using solution method with refluxing at 90  C for one hour. Zinc acetate dihydrate of different concentration was used as a source material with sodium hydroxide. Variation in concentration resulted in various structures like belts, flowers and sheets as observed by field emission electron microscopy (FE-SEM). High resolution transmission electron microscopic (HR-TEM) observations revealed that nanostructures grew along [0001] direction with an ideal lattice fringe dis- tance of 0.52 nm, same as that of bulk ZnO. Hydrogen adsorption studies carried out using sievert’s apparatus resulted in highest hydrogen adsorption value of ∼1.873 wt% for nanobelts and the lowest values for flower like structures. KEYWORDS: Heterostructured, ZnO, Solution Method. 1. INTRODUCTION The hydrogen economy development and is a key goal for the technocrats and scientists. Hydrogen can be produced during electrolysis of water, but the procedure is signif- icantly more expensive than the production from natural gas. Instead of burning carbon-based fossil fuels, if the energy used for splitting water is obtained from renew- able or nuclear power sources, then, a hydrogen economy would greatly reduce the emission of carbon dioxide and therefore would play a major role in tackling the global warming. The claim that hydrogen is an environmentally cleaner source of energy has attracted a great deal of attention towards a green energy regime. However, the mass and volume density is the current barrier to prac- tical storage schemes. Researchers are putting extensive efforts in exploring the approaches to absorb molecular hydrogen into a solid storage material that could pro- vide better solution without much limitation. Scientists have found that these absorbers could be metal-organic frameworks (MOFs), nano structured carbons (including carbon nano-tubes (CNTs)) and clathrate hydrate. 1–2 Car- bon nanotubes are recently studied for hydrogen storage ∗ Author to whom correspondence should be addressed. Email: hsshin@jbnu.ac.kr Received: Accepted: due to their excellent physical and chemical properties. 1–2 Dillon et al., were among the first few to report the hydrogen adsorption capacity of pure single wall CNTs at 133 K, as 5 to 10 weight%. 3 Chambers et al., claimed that tubular, platelet, and herringbone forms of carbon nanofibers were capable of adsorbing in excess of 11, 45, and 67 weight% of H 2 respectively, at room temperature. 4 Wan et al., reported hydrogen storage capacity of about 0.83 weight% at room temperature for ZnO nanowires prepared by thermal evaporation of metallic zinc. 5 Their report increased our interest in exploring H 2 -storage prop- erties of ZnO by synthesizing various nanostructures using different route i.e., solution method. Apart from this, enormous efforts are already being paid to know the prop- erties of heterostructures semiconductor nanomaterials. 6 In this connection, over the different metal oxide semicon- ductor nanostructures zinc oxide is known to its versatile quality, variety of nanostructures and application in vari- ous fields such as light emitting diodes (LED), field-effect transistors (FET), ultra violet nanolasers, solar cells and acoustic/electrical devices, gas sensors etc and many more needs to be investigated. 6 7–17 Thermal evaporation and hydrothermal method have been reported, for the fabrica- tion of different types of zinc oxide nano structures such as nanowires, nanobelts, nanobridges, nanonails, nanorib- bons, nanorods, nanotubes, and whiskers etc. 18–23 Addi- tionally, other methods are also employed for the synthesis J. Nanoeng. Nanomanuf., 1, 1–8, 2012 2157-9326/2012/1/001/008 doi:10.1166/jnan.2012.1025 1