In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications.

Efficient separation of photogenerated electrons and holes, and associated surface reactions, is a crucial aspect of efficient semiconductor photocatalytic systems employed for photocatalytic hydrogen production. A new CoO /TiO /Pt photocatalyst produced by template-assisted atomic layer deposition is reported for photocatalytic hydrogen production on Pt and CoO dual cocatalysts. Pt nanoclusters acting as electron collectors and active sites for the reduction reaction are deposited on the inner surface of porous TiO nanotubes, while CoO nanoclusters acting as hole collectors and active sites for oxidation reaction are deposited on the outer surface of porous TiO nanotubes. A CoO /TiO /Pt photocatalyst, comprising ultra-low concentrations of noble Pt (0.046 wt %) and CoO (0.019 wt %) deposited simultaneously with one atomic layer deposition cycle, achieves remarkably high photocatalytic efficiency (275.9 μmol h ), which is nearly five times as high as that of pristine TiO nanotubes (56.5 μmol h ). The highly dispersed Pt and CoO nanoclusters, porous structure of TiO nanotubes with large specific surface area, and the synergetic effect of the spatially separated Pt and CoO dual cocatalysts contribute to the excellent photocatalytic activity.

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The synergistic nature of bicomponent catalysts remains a challenging issue, due to the difficulty in constructing well-defined catalytic systems. Here we study the origin of synergistic effects in CoOx-Pt catalysts for selective hydrogenation by designing a series of closely contacted CoOxPt/TiO2 and spatially separated CoOx/TiO2/Pt catalysts by atomic layer deposition (ALD). For CoOx/TiO2/Pt, CoOx and platinum are separated by the walls of titania nanotubes, and the CoOx-Pt intimacy can be precisely tuned. Like CoOxPt/TiO2, the CoOx/TiO2/Pt shows higher selectivity to cinnamyl alcohol than monometallic TiO2/Pt, indicating that the CoOx-Pt nanoscale intimacy almost has no influence on the selectivity. The enhanced selectivity is ascribed to the increased oxygen vacancy resulting from the promoted hydrogen spillover. Moreover, platinum-oxygen vacancy interfacial sites are identified as the active sites by selectively covering CoOx or platinum by ALD. Our study provides a guide for the understanding of synergistic nature in bicomponent and bifunctional catalysts.

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Oxidative molecular layer deposition (oMLD) was applied to fabricate conductive polymer-magnetic material core-shell microwave absorbers in this work. One dimensional FeO-poly(3,4-ethylenedioxythiophene) (PEDOT) nanospindles with controllable PEDOT thickness were successfully synthesized. Their absorption performance was evaluated in the 2-18 GHz frequency range. With the advantage of oMLD, PEDOT shell thicknesses can be controlled precisely. Because the permittivity of FeO-PEDOT nanospindles obviously increases while their permeability decreases slightly with the PEDOT cycles, the properties can be tuned effectively by only adjusting the PEDOT cycle number. With a proper PEDOT shell thickness, excellent reflection characteristics can be obtained. Remarkably high absorption strength (-55.0 dB at 16.2 GHz) and good absorption bandwidth (4.34 GHz less than -10 dB) were realized. Such excellent performance is better than that reported previously for most magnetic material-based absorbers. Considering the precise controllability and excellent absorption performance of the prepared microwave absorbers, we believe that oMLD is a facile synthetic route for microwave absorbers.

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