Vapour-phase route simplifies production of 2D material MXene

A chemical vapour deposition route could make MXenes easier to produce at scale for electronics and quantum technologies.

The vapour-phase process reportedly produces crystalline MXenes directly from lower-cost starting materials, avoiding MAX phase synthesis and acid etching.

Conventional MXene manufacture starts with a powdered MAX phase precursor, which is then etched with chemicals such as hydrofluoric acid, washed and repeatedly centrifuged. The new process, developed at Drexel University, USA,  instead uses titanium tetrachloride and methane, alongside a solid titanium source, to grow crystalline MXene directly onto a quartz substrate.

The team has found that increasing the exposed titanium surface area and confining the reaction inside a narrow carrier tube improves growth. Under these conditions, the MXene forms on the quartz without coming into direct contact with the solid titanium, creating porous, rounded structures known as spherulites.

As the synthesis time increases, the spherulites grew and merge, forming larger crystalline regions with flakes tens of micrometres across.

The researchers say the continued lateral growth suggests the process could be used to produce large-area or wafer-scale, low-defect, MXene films for electronics, optics and quantum technologies.

They are now working to improve structural uniformity, increase flake size and gain tighter control over surface chemistry.