Morphology dependence of Nb 2 O 5 -supported cobalt oxide in catalytic toluene oxidation

This research describes the preparation of cobalt-based catalysts supported on Nb 2 O 5 substrates of various forms: rods (Nb 2 O 5 -R), grids (Nb 2 O 5 -G), and spherical structures (Nb 2 O 5 -S). These catalysts demonstrated diverse reactivity in toluene oxidation, which correlated with their individual physical and chemical traits and the interfacial interaction between cobalt oxide and the Nb 2 O 5 support. Notably, the catalyst with a spherical Nb 2 O 5 support (CoO x /Nb 2 O 5 -S) outperformed the catalysts with other supports and showed the best activity in oxidizing toluene. The investigation underscored the role of the unique features of the Nb 2 O 5 substrate in augmenting the catalyst's efficacy in toluene adsorption and activation. Density functional theory (DFT) revealed more facile toluene adsorption on CoO x /Nb 2 O 5 -S (−0.65 eV) and reduced energy requirements for oxygen vacancy creation and adsorption. This suggested that the CoO x /Nb 2 O 5 -S catalyst enhanced surface oxygen mobility and boosted catalytic efficiency.