We successfully demonstrate the electrochemical etching of Al from porous Ti2AlC in dilute hydrochloric acid to form a layer of Ti2CTx MXene on Ti2AlC. This is the first report on etching of the A layer from the MAX phase in a fluoride-free solution. In addition, these MXenes possess only –Cl terminal groups, as well as the common ones, such as –O and –OH. However, electrochemical etching can also result in subsequent over-etching of parent MAX phases to carbide-derived carbon (CDC). We propose a core–shell model to explain electrochemical etching of Ti2AlC to Ti2CTx and CDC. The proposed model suggests that a careful balance in etching parameters is needed to produce MXenes while avoiding overetching. Our electrochemical approach expands the possible range of both etching techniques and resulting MXene compositions.

Electrochemical etching of Ti2CTx MXene in dilute HCl solution

255th National Meeting (2018)

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