Catalytic mechanism of the Schikorr reaction promoted by the copper oxide nanosheet during a low-temperature hydrothermal process

The Schikorr reaction 3Fe(OH) 2 → Fe 3 O 4  + H 2  + 2H 2 O, has been proposed for nearly 100 years. Although it has shown great potential application value in steel corrosion, recovery of ferrous waste liquid, and other fields, the reaction catalyst itself is still unclear. We confirmed that Cu(II) ions were essentially converted into the oriented CuO nanosheets as a catalyst during a low-temperature hydrothermal process. Moreover, this catalytic reaction required the participation of hydroxide ions without relationship to sulfate ions and trace dissolved oxygen molecules in the solution. The growth process tracing experiment found that green rust was the reaction intermediate, and the reaction stage from green rust to Fe 3 O 4 was the reaction rate control stage. Finally, the reaction rate was clearly defined by using the FWHM of the XRD diffraction peak of the (3,1,1) crystal plane of Fe 3 O 4 , and the activation energy was calculated as 79.46 ± 5.05 kJ mol −1 .