Fabrication of NiO/SiO2 nanocomposites using sol–gel method and optimization of gelation time using Taguchi robust design method

The present work deals with the synthesis of NiO/SiO2 nanocomposites fabricated by embedding nickel oxide particles, obtained from hexahydrated nickel nitrate (Ni(NO3)2·6H2O), in a silica matrix, through sol–gel method based on hydrolysis and condensation of tetraethyl orthosilicate (TEOS) alkoxide. Due to the various factors, e.g. pH, EtOH/TEOS/H2O ratio, Si/Ni ratio, etc., influencing the gelation time of the solutions, Taguchi robust design method of system optimization was used to determine the percent of contribution (%ρ) of each factor. It was found that the pH of the solutions had the most influence on the gelation time (68.76%) and the Si/Ni atomic ratio stood in second place (12.95%). It was illustrated that the molar ratio of EtOH/TEOS had the least influence on the gelation time.