Amorphous Mo@Moo2 Supported Low-Crystalline Co Nanosheets for Enhanced O-H Bond Cleavage: Synergistic Effect of Abundant Active Sites and Robust Interfaces

Abstract

The activation of the H₂O molecule serves as the rate-determining step for H2 evolution from the photo-assisted hydrolysis of ammonia borane (NH₃BH₃). Therefore, developing a low-cost efficient catalyst that can expedite the cleavage of O–H bonds in H₂O is needed for improving hydrogen production efficiency in practical application. Here, we prepared a supported non-noble metal catalyst (Co/Mo@MoO2-200) with abundant active sites, comprising ultrathin low-crystalline Co nanosheets grown on amorphous MoO2-coated Mo nanoparticles, as a high-performance non-noble metal catalyst to accelerate the activation of O-H bonds in H2O. Notably, visible light irradiation facilitates the formation of ultrathin Co nanosheets by inducing plasmon resonance effect of MoO2, as verified by TEM images. Meanwhile, XANES and XPS spectra confirm electron transfer from Co nanosheets to O sites in Mo@MoO2-200, establising robust interfaces. The Co/Mo@MoO2-200 exhibits high catalytic performance with the TOF value of 113.92 min-1 under visible light irradiation, that outperform 1.21 times than that of Co/Mo and most of reported Co-based catalyst. DFT calculations reveal that the Mo@MoO2-200 support in catalyst can promote the Co-adsorption of NH3BH3 and H2O, while facilitates H2 desorption. Importantly, the Co/Mo@MoO2-200 can greatly decrease the activation energy barrier of the O-H bond in H2O, compared with pristine Co and Mo@MoO2-200. This work offers a flexible catalyst design strategy for NH3BH3 hydrolysis and other H2O-associated catalytic reactions.

Keywords: Hydrogen evolution, Photocatalytic, Cleavage of O-H bonds, Co nanosheets, Robust interfaces