Oxygen vacancy-attired dual-active-sites Cu/Cu0.76Co2.24O4 drives electron transfer for efficient ammonia borane dehydrogenation

In the ammonia borane (AB) hydrolysis reaction, overcoming the weak activation of H2O by metal catalysts can be achieved by introducing transition metal oxides (TMOs) for catalyst active-sites design. Herein, we uncovered that oxygen vacancy (VO)-attired Cu/Cu0.76Co2.24O4 dual-active-sites catalysts significantly increase the hydrogen production rate of AB hydrolysis. The turnover frequency of Cu/Cu0.76Co2.24O4-VO dehydrogenation in 0.10 M NaOH can reach 50.33 molH2/(molcat.min), which is 45.9 times that of metal Cu. By means of a joint experimental and computational study, the VO defects promote the formation of electron-rich surface of Cu0.76Co2.24O4, and the Cu also enriches the surface electrons due to the strong interaction with TMOs, which enhances the activation of O-H and B-H bonds, respectively, and significantly accelerates the rate-determining step of the reaction. This work demonstrates the important role of constructive defects in regulating surface electrons of dual-active-sites catalysts on the performance enhancement and provides a broader idea for the design of excellent AB hydrolysis catalysts.