Crystalline−Amorphous Phase Engineering of Mo-Doped Co3O4 Support for Efficient Pt Utilization in Hydrogen Generation

Developing supported noble metal catalysts with high atom efficiency remains a central challenge for hydrogen generation from ammonia borane (AB) hydrolysis. Herein, we report a crystalline–amorphous phase engineering strategy to construct a hybrid Co3O4/CoMoOx support that dramatically enhances the utilization efficiency of Pt. Starting from Mo-doped ZIF-67, the support spontaneously evolves into an interfacial structure comprising crystalline Co3O4 nanoparticles and amorphous CoMoOx nanosheets during catalyst preparation. This unique architecture enables strong metal–support interaction, as evidenced by XPS and DFT calculations: Pt at the interface adopts an electron-rich state with an upshifted d-band center, in sharp contrast to the electron-deficient Pt on pristine Co3O4 or isolated CoMoOx. Consequently, the optimized catalyst achieves an outstanding turnover frequency of 50,329 min−1 at 298 K with addition of 0.44 M NaOH (Pt/AB molar ratio as low as 0.000031), representing one of the highest reported activities for AB hydrolysis. DFT calculations further reveal that the crystalline–amorphous interface simultaneously lowers the kinetic barriers for both H2O dissociation and NH3BH3 activation, establishing a unified catalytic center, rather than merely partitioning catalytic functions. This study demonstrates that the rational engineering of phase boundaries represents a viable strategy for enhancing the catalytic efficiency of noble metals and designing the efficient and cost-effective catalysts via electronic structure modulation.