Effective metal encapsulation of carbon nanotubes by micro-current electrochemical deposition

The inner cavities of carbon nanotubes (CNTs) have attracted much attention for one-dimensional structures and their unique properties. The encapsulation of hetero-structures into CNTs is the foundation for potential applications. Solution and vapor methods have been well adopted for CNTs encapsulations. The solution method is restricted to its low encapsulation yield. Only chemicals with relatively low sublimation points under low pressures and low activity have been demonstrated to be encapsulated into the inner cavities of CNTs by vapor methods. No effective encapsulation method for most metals has been explored so far. Now, a widely applicable metal encapsulation method, micro-current electrochemical deposition, has been demonstrated to encapsulate lithium, sodium and potassium metals into CNTs with high yield. The volumetric encapsulation yields of lithium, sodium and potassium metal have been demonstrated to be higher than 65%. [Display omitted] •A micro-current electrochemical deposition method has been reported to encapsulate metals into MWCNTs.•The encapsulation yields of Li, Na and K have been demonstrated to be about 68%, 74%, and 75%, respectively.•The elemental status of the encapsulated metals was confirmed by elemental maps and hydrolysis reaction to yield hydrogen.•The encapsulation method has been explored to be an effective and widely applicable encapsulation method for metals.