Comprehensive preparation and catalytic activities of Co/TEMPO-cellulose nanocomposites: A promising green catalyst

A green method for the production of cobalt/(TEMPO-Cellulose) aerogel heterogeneous catalyst was developed. The preparation implied the reduction of CoSO₄ by NaBH₄ in TEMPO-Cellulose water dispersion in ambient conditions. The formation of Cobalt nanoparticles is due to the presence of "TEMPO-Cell" which screens the Co²⁺ ions and prevents their combination with boron. SEM, XRD, EDX, FTIR, TEM and XPS were used to analyze the structure of the catalyst and showed that metallic cobalt particles have nanometric size and are well dispersed in the aerogel. The catalyst showed excellent activity for model reactions such as the reduction of 4-nitroaniline, 4-nitrophenol and 2-nitrophenol in water, in the presence of NaBH₄. The reaction kinetic was studied by UV-visible spectroscopy, which showed that this catalyst is efficient to achieve 100 % reduction with high reaction rate and turnover frequency. The aerogel catalyst was reused more than ten times without significant loss of its catalytic activity.