Mesocrystals, the non-classical crystals with highly ordered nanoparticle superstructures, have shown great potential in many applications because of their newly collective properties. However, there is still a lack of a facile and general synthesis strategy to organize and integrate distinct components into complex mesocrystals, and of reported application for them in industrial catalytic reactions. Herein we report a general bottom-up synthesis of CuO-based trimetallic oxide mesocrystals (denoted as CuO-M1O_x-M2O_y, where M1 and M2 = Zn, In, Fe, Ni, Mn, and Co) using a simple precipitation method followed by a hydrothermal treatment and a topotactic transformation via calcination. When these mesocrystals were used as the catalyst to produce trichlorosilane (TCS) via Si hydrochlorination reaction, they exhibited excellent catalytic performance with much increased Si conversion and TCS selectivity. In particular, the TCS yield was increased 19-fold than that of the catalyst-free process. The latter is the current industrial process. The efficiently catalytic property of these mesocrystals is attributed to the formation of well-defined nanoscale heterointerfaces that can effectively facilitate the charge transfer, and the generation of the compressive and tensile strain on CuO near the interfaces among different metal oxides. The synthetic approach developed here could be applicable to fabricate versatile complicated metal oxide mesocrystals as novel catalysts for various industrial chemical reactions.

Four kinds of CuO catalysts with well-controlled leaf-like (L-CuO), flower-like (F-CuO), sea-urchin-like (U-CuO), and oatmeal-like (O-CuO) morphologies were synthesized by a facile precipitation method assisted by various chelating ligands. High-resolution transmission electron microscopy and fast Fourier transform infrared spectroscopy indicated that the dominant crystal facets of L-CuO, F-CuO, U-CuO, and O-CuO were {001}, {110}, {001}, and {110}, as well as {001} and {110}, respectively. When tested for the Rochow reaction, it was found that their catalytic performances were dependent on their structures. Among the four CuO catalysts, L-CuO exhibited the best catalytic property, along with the strongest adsorption ability for oxygen and highest reducibility, which are mainly because of its largely exposed {001} facet and large specific surface area. In addition, the amount of the Cu₃Si alloy phase, which is the most important reaction intermediate that generated in the reacted region of the Si surface, was measured for the different catalysts. Based on the findings, a detailed reaction mechanism was proposed. This work demonstrates that shape-controlled synthesis of oxide catalysts could be an effective strategy to design and develop efficient catalysts.

Hierarchically heterostructured hollow spheres are of great interest for a wide range of applications owing to their unique structural features and properties. However, the fabrication of well-defined hollow spheres with highly specific morphology for mixed transition metal oxides on a large scale remains challenging. In this work, uniform rambutan-like heterostructured CeO₂-CuO hollow microspheres with numerous copper–ceria interfacial sites and nanorods and nanoparticles as building blocks are prepared via a facile hydrothermal method followed by calcination. Importantly, this approach can be readily scaled up and is applicable to the synthesis of various CuO-based mixed metal oxide complex hollow spheres. The as-prepared CeO₂-CuO hollow rambutans exhibit superior performance both as electrode materials for supercapacitors and as Cu-based catalysts for the Rochow reaction, mainly due to the small primary nanoparticle constituents, high surface area, and formation of numerous interior heterostructures.

A series of copper catalysts with a core–shell or tubular structure containing various contents of Cu, Cu₂O, and CuO were prepared via controlled oxidation of Cu nanowires (NWs) and used in the synthesis of dimethyldichlorosilane (M2) via the Rochow reaction. The Cu NWs were prepared from copper (Ⅱ) nitrate using a solution-based reduction method. The samples were characterized by X-ray diffraction, thermogravimetric analysis, temperature-programmed reduction, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. It was found that the morphology and composition of the catalysts could be tailored by varying the oxidation temperature and time. During the gradual oxidation of Cu NWs, the oxidation reaction initiated on the outer surface and gradually developed into the bulk of the NWs, leading to the formation of catalysts with various structures and layered compositions, e.g., Cu NWs with surface Cu₂O, ternary Cu–Cu₂O–CuO core–shell NWs, binary Cu₂O–CuO nanotubes (NTs), and single CuO NTs. Among these catalysts, ternary Cu–Cu₂O–CuO core–shell NWs exhibited superior M2 selectivity and Si conversion in the Rochow reaction. The enhanced catalytic performance was mainly attributed to improved mass and heat transfer resulting from the peculiar heterostructure and the synergistic effect among layered components. Our work indicated that the catalytic property of Cu-based nanoparticles can be improved by carefully controlling their structures and compositions.