An In Situ Dealloying and Oxidation Route to Co₃O₄ Nanosheets and their Ambient‐Temperature CO Oxidation Activity

Co 3 O 4 nanosheets are straightforwardly fabricated through an in situ dealloying and oxidation process of etching CoAl alloy in alkaline solutions. X‐ray diffraction and electron spectroscopy characterizations demonstrate the formation of a Co 3 O 4 nanostructure with an intricate hierarchical nanosheet morphology comprising interconnected nanoslices with the diameter as small as 6 nm. Upon calcination in O 2 atmosphere, these novel Co 3 O 4 nanosheets exhibit excellent catalytic activity toward CO oxidation in normal feed gas at ambient temperature. Catalytic tests reveal the strong influence of calcination temperature on the resultant catalytic activities, whereby 300 °C is found to be preferable possibly due to an optimum balance between the surface area and the amount of active species as compared with 200 and 450 °C. Moreover, Co 3 O 4 nanosheets showed good time‐on‐stream catalytic stability; CO conversion at T 50 (the temperature for 50 % CO conversion) reduced to 37 % after 20 h, and at T 100 (the temperature for full CO conversion) the conversion only decreased to about 90 % after 15 h.