Nickel oxide (NiO) nanorings were synthesized by controllable thermal decomposition of precursor Ni(OH)(2) nanoplates obtained via the reaction between Ni(NO(3))·6H(2)O and NaOH under hydrothermal conditions. The process of their formation was investigated and an unexpected catalytic property of this novel-shaped material is reported for CO oxidation.

Highly dispersed Ni catalyst and alkaline promoters supported by mesoporous SiO₂ nanospheres were synthesized and applied as an active and stable catalyst for dry reforming of methane (DRM). The as-prepared Ni/MgO-mSiO₂ catalyst showed stable conversions of CH₄ and CO₂ around 82% and 85% in 120 h of DRM reaction, which was superior in performance compared to similar catalysts in literatures. Based on the transmission electron microscope (TEM) images, energy-dispersive spectroscopy (EDS), CO-pulse adsorption, temperature programmed reduction of the oxidized catalysts by hydrogen (H₂-TPR), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of CO₂ (CO₂-TPD), and thermal gravitational analysis (TGA), the promotion effect of MgO on the Ni catalyst was systematically studied. The introduction of Mg²⁺ in synthesis enhanced the interaction between Ni²⁺ and mSiO₂, which led to a high dispersion of active centers and a strong “metal-support” interactions to inhibit the sintering and deactivation of Ni at reaction temperatures. On the other hand, Ni and MgO nanoparticles formed adjacently on mSiO₂, where the “Ni-MgO” interface not only improved the Ni⁰ distribution and promoted the cracking of CH₄ but also promoted the activation of CO₂ and the elimination of carbon deposits. A high and stable conversion of CH₄ and CO₂ were then achieved through the synergistic effect of Ni catalyst, MgO promoter, and mSiO₂ support.