Co and CoO in the Hydrolysis of Boron-Containing Hydrides: HO Activation on the Metal and Oxide Active Centers.

This work focuses on the comparison of H evolution in the hydrolysis of boron-containing hydrides (NaBH, NHBH, and (CHNHBH)) over the Co metal catalyst and the CoO-based catalysts. The CoO catalysts were activated in the reaction medium, and a small amount of CuO was added to activate CoO under the action of weaker reducers (NHBH, (CHNHBH)). The high activity of CoO has been previously associated with its reduced states (nanosized CoB). The performed DFT modeling shows that activating water on the metal-like surface requires overcoming a higher energy barrier compared to hydride activation. The novelty of this study lies in its focus on understanding the impact of the remaining cobalt oxide phase. The XRD, TPR H, TEM, Raman, and ATR FTIR confirm the formation of oxygen vacancies in the CoO structure in the reaction medium, which increases the amount of adsorbed water. The kinetic isotopic effect measurements in DO, as well as DFT modeling, reveal differences in water activation between Co and CoO-based catalysts. It can be assumed that the oxide phase serves not only as a precursor and support for the reduced nanosized cobalt active component but also as a key catalyst component that improves water activation.