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Copper nanoparticles filled carbon nanotubes (CNTs) with varied tube diameters were prepared via a convenient sonication-assisted impregnation approach. CNTs and Cu nanoparticles filled CNTs were thoroughly investigated using transmission electron microscopy, Raman spectroscopy, N 2 adsorption, X-ray diffraction, and H 2 temperature programmed reduction. Confinement effects of CNTs, originated from its diameter and microstructure, on the filled Cu nanoparticles were discovered. For CNTs with smaller tube diameter, a consequential strong autoreduction for the confined Cu nanoparticles was observed, which showed a downward trend with the increasing anneal temperature. Methyl acetate (MeOAc) hydrogenation forming methanol and ethanol was chosen as model reaction to further explore the influence of CNTs confinement effects on the catalytic performance. In the case of catalysts derived from CNTs with smaller inner diameter (4−10 nm), their catalytic performance were improved after the CNTs heat treatment under Ar atmosphere and the optimum treatment temperature was 973 K. On the contrary, the CNTs catalysts with larger inner diameter (20−30 nm) exhibited reduced catalytic activity after the same heat treatment. In addition, the selectivity to ethanol from MeOAc was also found dependent on CNTs tube diameter. Furthermore, the Cu nanoparticles loaded outside of CNTs catalyst were prepared and compared with the Cu nanoparticles filled inside CNTs catalyst, and the latter exhibited higher catalytic activity because of the confinement effects of CNTs. All in all, when using CNTs as support materials, the likely synergistic effects created by CNTs diameter, the pretreatment on CNTs, and the nanocatalyst loaded inside or outside CNTs are responsible for the catalytic activity of the prepared catalysts. These findings propose an in-depth insight into the confinement of CNTs to the filled metal catalysts, and thus inspire the development of novel catalyst with beneficial catalytic performance.

Porous ternary metal sulfide integrated electrode materials with abundant electroactive sites and redox reactions are very promising for supercapacitors. Herein, a porous zinc cobalt sulfide nanosheet array on Ni foam (Zn-Co-S/NF) was constructed by facile growth of 2D bimetallic zinc/cobalt-based metal-organic framework (Zn/Co-MOF) nanosheets with leaf-like morphology on NF, followed by additional sulfurization. The Zn-Co-S/NF nanosheet array acted directly as a supercapacitor electrode showing much better electrochemical performance (2354.3 F g and 88.6 % retention over 1000 cycles) when compared with zinc cobalt sulfide powder (355.3 F g and 75.8 % retention over 1000 cycles), which originates from good electrical conductivity and mechanical stability, abundant electroactive sites, and facilitated transportation of electrons and electrolyte ions due to the unique nanosheet array structure. An asymmetric supercapacitor (ASC) device assembled from Zn-Co-S/NF and activated carbon electrodes can deliver a highest energy density of 31.9 Wh kg and a maximum power density of 8.5 kW kg . Most importantly, this ASC also shows good cycling stability (71.0 % retention over 10000 cycles). Furthermore, a red LED can be powered by two connected ASCs, and thus as-synthesized Zn-Co-S/NF has great potential for practical applications.

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Copper is “frozen” into a metallic state as a noble metal–like catalyst for controlling the product in a chemical reaction.

A hierarchical Ni–Co–S nanosheet array is realized via a facile 2D Co-MOF templating method and it shows enhanced capacitive performance.

High energy density is achieved on an electrode based on ultrathin Ni-MOF nanosheet arrays grown on PANI decorated NF.