Synthesis and characterization of cobalt-based layered double hydroxides for light-driven CO2 reduction

The influence of cobalt on the photocatalytic reduction of CO2 under visible light was examined by using various 3:1 Co-Mg/Al layered double hydroxides (LDHs) obtained by coprecipitation under low oversaturation condi-tions. CO2 photoreduction increased with increasing amount of cobalt in the solids. Calcining the LDHs gave basic mixed oxides (LDOs) with considerably decreased activity, thus confirming that the hydroxyl structure of the materials facilitated the photocatalytic process. Attempts at reconstructing the LDOs revealed that only the material with the smallest amount of cobalt regained its original structure -and exhibited excellent performance in the reaction. All solids were characterized by using various instrumental techniques and used as catalysts in the photocatalytic reduction of CO2. Also, the fully reconstructed material was reused with no substantial loss of activity.