Cobalt Oxides and Co-Al Mixed Oxides as Thermo-, Photo- and Electrocatalytic Materials: Properties and Perspectives of Industrial Applications

The literature data on the solid-state and surface chemistry of cobalt and cobalt–aluminum oxide and hydroxide systems are reviewed. The actual and potential applications of these materials in the fields of catalysis, electrocatalysis, photocatalysis, adsorption and sensor technologies are reviewed. A comprehensive analysis of the peculiar redox and acid–base properties of these cobalt-based systems, both at the solid–gas and at the solid–water solution interface, is conducted. Evidence is provided for the exceptional versatility of these systems and on their relevant potential for optimal applications, in particular, in several catalytic total oxidation reactions, in N2O catalytic decomposition, in ammonia catalytic oxidation to NO, as electrocatalysts in water splitting reactions, as active elements in supercapacitors, and as precursors of cobalt metal-based systems. It is underlined that these systems could successfully substitute more critical and expensive noble metal-based systems in several technological fields.