Amorphous MoO2-wrapped Mo supported low-crystalline Co nanosheets for enhanced OH bond cleavage: synergistic effect of abundant active sites and robust interfaces
The activation of the water molecule (H₂O) serves as the rate-determining step for hydrogen (H 2 ) 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 applications. Here, we prepared a supported non-noble metal catalyst (Co/Mo@MoO 2 –200) with a large number of active sites, comprising ultrathin low-crystalline cobalt (Co) nanosheets grown on amorphous molybdenum oxide (MoO 2 )-coated molybdenum (Mo) nanoparticles (Mo@MoO 2 –200), which serves as a high-performance non-noble metal catalyst to accelerate the activation of O H bonds in H 2 O. Notably, visible light irradiation facilitates the formation of ultrathin Co nanosheets by inducing the localized surface plasmon resonance of MoO 2 , as verified by transmission electron microscopy (TEM) images. Moreover, X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopy (XPS) spectra confirm the electron transfer from Co nanosheets to O sites in Mo@MoO 2 –200, establishing robust interfaces. Co/Mo@MoO 2 –200 exhibits high catalytic performance with the turnover frequency (TOF) value of 110.8 min −1 under visible light irradiation, which is greater than that of Co/Mo by 1.21 times and most of the reported Co-based catalysts. DFT calculations reveal that the Mo@MoO 2 –200 support in the catalyst can promote the Co-adsorption of NH 3 BH 3 and H 2 O, while facilitating H 2 desorption. Particularly, the Co/Mo@MoO 2 –200 can significantly decrease the activation energy barrier of the O H bond in H 2 O, compared with pristine Co and Mo@MoO 2 –200. This paper presents a flexible catalyst design strategy for NH 3 BH 3 hydrolysis and other H 2 O-associated catalytic reactions.
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