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Inspired by the antibacterial agents, such as ethylene oxide, anacardic acid, and salicylic acid, oxygen‐terminated carbon bonds may take the major responsibility in antibacterial properties, a layer of oxygen‐terminated carbon bonds is fabricated on nanodiamond as an immobilized coating for the investigation of the antibacterial activity. The results demonstrate comparable antibacterial activities on oxygen‐terminated nanodiamond coating (NDC) against two kinds of probe bacteria, Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus, and the annealing method as a proper method for the improvement of the antibacterial performance of the NDC. The concentration of oxygen‐terminated carbon bonds, especially CO and CO, and the ratio of CO to CO, are found to determine the antibacterial performance of NDCs. The antibacterial behavior performed through the surface interaction is revealed and the abnormal expression of cell wall‐related proteins are identified, where a potential antibacterial mechanism is proposed: the oxygen‐terminated carbon bonds damaged the cell wall through the blockage and the electrostatic repulsive force, which aggravated the abnormal metabolism of bacteria and lead to its death. The antibacterial property of oxygen‐terminated carbon bonds is confirmed and its application, NDC, provides a new idea for antibacterial research and opens the door to antibacterial coatings for medical devices.

Dendritic-like Co superstructures based on the self-assembly of nanoflakes that could efficiently suppress the eddy current were successfully synthesized via a facile, rapid, and energy-saving chemical reduction method. Since crystal structure, size, and special geometrical morphology, magnetism have a vital influence on microwave absorption properties, the as-obtained products were characterized by x-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, and vector network analysis. The prepared dendritic Co possesses abundant secondary branches that extend to the 3D space. Their dimensions, spacing, sheet-like blocks, and high-ordering microstructures all contribute to the penetration, scattering, and attenuation of EM waves. The composites present attractive microwave absorption performances in the X band, as well as in the whole S band (2-4 GHz). This work investigates the mechanism of absorption for the as-obtained Co, offers a promising strategy for the fabrication of hierarchical Co microstructure assemblies by multi-leaf flakes and introduces the application of dendritic-like Co as a highly efficient absorber in the S band and X band.

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