Molybdenum is known to increase the acidity of metal oxides by introducing Lewis acid sites in to the material. We developed a method to introduce Mo6+ ions in the place of Co3+ ions in the Co3O4 cubic lattice and the optimum Mo concentration was determined. Insertion of Mo ions leads to an increase in the d-spacing in the Co3O4 crystal domain and the inter-planer distances for materials with different doping concentrations were calculated according to Bragg’s law using powder X-ray diffraction data. An increase in acid sites upon the introduction of Mo was determined by CO2 adsorption data and the acid-base character could be adjusted by selecting the appropriate dopant concentrations. Pure Co3O4 showed the least acidity and the highest acidities were observed for the sample with 3% Mo/Co molar ratio. Molybdenum was found to be in its Mo6+ oxidation state and successful substitution of Co3+ with Mo6+ was observed by X-ray photoelectron spectroscopy. Furthermore, Mo incorporation led to an increase in surface area and oxygen vacancies of the material due to the creation of surface defects.

Molybdenum promoted mesoporous Co3O4: Study of acid-base switchable surface chemistry

255th National Meeting (2018)

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