Ni–MoO2 heterostructure encapsulated in mesoporous silica microtubes: a structured hydrogenation catalyst with enhanced activity for reduction of 4-nitrophenol

Metallic Ni catalysts often suffer from serious aggregation and poor stability during the process of catalysis. In this work, core–shell nanostructures with nanosized MoO₂–Ni nanoparticles (NPs) and mesoporous SiO₂(mSiO₂) shells were well designed to address these issues. The Ni–MoO₂ hybrid cores were converted from hierarchical NiMoO₄ microtubes inside the SiO₂ shell through carbonization treatment to remove the hexadecyl trimethyl ammonium bromide (CTAB) template under the protection of a nitrogen atmosphere. The mesoporous SiO₂ shells in Ni–MoO₂@mSiO₂ nanoreactors prevented the agglomeration/sintering of Ni NPs, while allowing the mass diffusion of small molecules. Owing to the high catalytic performance of Ni–MoO₂ cores, good protection of mesoporous silica, and the unique sandwich-like structure, the obtained Ni–MoO₂@mSiO₂ nanoreactors showed tremendous improvement in catalytic activity and stability.