Influence of calcination temperature on sol-gel surfactant derived micro-mesoporous cobalt silica

This work investigates the effect of calcination temperature on the sol-gel structural properties of surfactant (hexyl trimethyl ammonium bromide (HTAB)) derived cobalt silica xerogels. Experimental results revealed that no significant changes were detected on the structure and cobalt state beyond 400 °C for samples with low surfactant/Co loads ( x ≤1). Pore structure and Co ₃ O ₄ phase showed almost similar values for calcination temperature from 400 to 600 °C. In contrast, the incorporation of an excess amount of surfactant ( x =2 and 3) induced a delayed evolution of both properties beyond 400 °C, strongly suggesting an influence of the additional interactions between Co-Br complexes and surfactant. The additional metal-surfactant interaction induces a dual influence on the evolution of material properties throughout the heat treatment, partially inhibiting the oxidation of cobalt and significantly altering the mesoporous structure due to surfactant removal at temperatures in excess of 400 °C.