Synthesis of bimodal mesoporous Ni oxide from octylamine

Mesoporous Ni hydroxynitrates were synthesized from a hydrothermal mixture of Ni nitrate, octylamine as the surfactant, ethanol and water at 25–100 °C for 24 h. Mesoporous Ni oxides were obtained by calcining the Ni hydroxynitrates in air at temperatures ranging from 200 to 500 °C for 2 h. The mesoporous Ni oxides have crystalline walls, a high surface area of 133 m²/g at 350 °C, high porosity up to 0.61 cm³/g, and a bimodal mesopore size distribution, with pores roughly 2 and 10–25 nm in diameter. With an increase in the synthesis temperature, the size of the larger pores and the total pore volume of the mesoporous Ni oxide increase, while the surface area decreases slightly from 133 (25 °C) to 111 m²/g (100 °C).