Effects of Co ²⁺ doping on physicochemical behaviors of hierarchical NiO nanostructure

A series of Co ²⁺ doped NiO materials (Ni _1−x Co _x O with x = 0, 0.125, 0.25 and 0.5) were synthesized using a facile hydrothermal method followed by a calcination process. The effects of Co ²⁺ doping on the structural, morphological, magnetic and catalytic properties of NiO were systematically investigated. The results indicated that Co ²⁺ doping would bring about a series influence to the as-obtained NiO product. The XRD results indicated that within the region of 0 ≤ x ≤ 0.25 the doped products revealed a pure NiO phase. The elementary unit for the hierarchy NiO gradually transformed from nanosheets to nanoneedles with the increase of Co ²⁺ doping content. As-obtained Co ²⁺ doped NiO products showed ferromagnetism at room temperature and the magnetization value was increased with the increase of Co ²⁺ doping content. The catalytic properties of NiO concerning the thermal decomposition of ammonium perchlorate (AP) were significantly improved via the introduction of Co ²⁺ . The Ni _1−x Co _x O products with x = 0.25 showed the best catalytic performance to AP, which could decrease the beginning and ending decomposition temperature of AP by 44 and 108 °C. The change of morphology, enhancement of electrical conductivity and the synergistic effect between Co ²⁺ and NiO were the main factors responsible for the improvement of physicochemical behaviors.