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Supported Ni catalysts are promising for CO2 hydrogenation because of their relatively cheap price with comparable activity to noble metal catalysts. The product of CO2 hydrogenation over a supported Ni catalyst can theoretically be methane, CO, methanol and formic acid. The electronic and geometric structures of a supported Ni catalyst have a significant effect on the activity and selectivity of CO2 hydrogenation. Supported single nickel atom catalysts are found to tend to form carbon monoxide, methanol and, theoretically, formic acid. The selectivity depends on the support. The supported nickel cluster on indium oxide and In2O3–ZrO2 is highly selective for methanol synthesis. Supported nickel nanoparticles are normally good catalysts for methane formation at reasonably low temperatures. However, the structural effect of the supported Ni catalyst on CO2 hydrogenation has not been well investigated. The mechanism is still in debate. To further improve the activity and stability with tunable selectivity, the structure control of the Ni catalyst is very necessary for CO2 hydrogenation, which is highly structure sensitive. In this review, recent advances in the understanding of the structural effects of supported Ni catalysts on CO2 hydrogenation are summarized, including theoretical studies, operando or in situ catalyst characterization and experimental studies. Future development is therefore finally addressed. [ABSTRACT FROM AUTHOR]

Responsive polymers have been widely studied as actuators in response to external stimuli and exhibit promising applications in wide variety of fields. However, the actuating direction of most polymers cannot be precisely controlled, and the generated low stress and poor stability cannot meet practical applications either. Herein, conjugated polymer/aligned multi-walled carbon nanotube (MWCNT) composites are designed, which can undergo anisotropic and reversible bending/unbending actuations driven by solvents. The actuating direction was accurately controlled to be perpendicular to the MWCNT length, which is realized through the orientation of conjugated polymers induced by aligned MWCNTs. The actuation generates a stress of 15 MPa, approximately 42 times of the strongest human muscle, and the reversible actuations are repeated for 300 cycles without fatigue. These composite artificial muscles can be widely used in numerous fields, such as sensors and actuators. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cell and electrochemical capacitor have been coaxially integrated into a novel “energy fiber” that can simultaneously realize photoelectric conversion and energy storage. A Ti wire substrate modified with perpendicularly aligned titania nanotubes on the surface and horizontally aligned multi-walled carbon nanotube sheet serve as two electrodes in the integrated “energy fiber” device. The “energy fiber” is flexible, and can be woven into various structures such as lightweight textiles to meet the portable facilities in the electronics. [ABSTRACT FROM AUTHOR]