Hydrogen storage of ZnO and Mg doped ZnO nanowires

ZnO nanowires without or with Mg doping were produced by thermally oxidizing pure Zn or (Zn + Mg) powders. X-ray diffraction (XRD) patterns indicated that ZnO nanowires with and without Mg doping were crystalline with wurzite structure. The highest hydrogen uptake capability was 2.79 wt% at room temperature and 860 psi for Mg-doped ZnO nanowires. 70.1% of the stored hydrogen can be released at ambient pressure. 2.57 wt% uptake and 68.3% release were measured for ZnO nanowires. Fourier transform infrared spectroscopy (FTIR) showed the formation of O–H bonds, while temperature programmed desorption (TPD) suggested that chemisorbed hydrogen could be released only at 100–250 °C. The H 2 absorption mechanism on ZnO is discussed.