Sol Gel-Based Synthesis of the Phosphorus-Containing MAX Phase V 2 PC.

More than 150 MAX phases are known to date. Their chemical diversity is the result of mixing-and-matching early-to-mid transition metals (M), main group elements (A), and carbon and/or nitrogen (X). The vast majority of the respective carbides and (carbo)nitrides contain group 13 and 14 as the A element, such as Al, Ga, and Si. V 2 PC is among the least studied members of this family of materials; as a matter of fact, it is only mentioned in two pieces of original literature. The solid-state synthesis is extremely vaguely described and working with elemental phosphorus poses additional synthetic challenges. Here, we confirm these experimental difficulties and present an alternative sol gel-based approach to prepare almost single-phase V 2 PC. The versatility of the sol gel chemistry is further demonstrated by variation of the gel-building agent moving beyond citric acid as the carbon source. DFT calculations support the experimentally obtained structural parameters and show V 2 PC is a metal.