Electrochemistry of layered metal diborides.

In the last decade, layered materials and their 2D counterparts, such as graphene, transition metal chalcogenides or black phosphorus, have been tested for their electrocatalytic properties. The main application is in the hydrogen evolution reaction (HER) and the oxygen reduction reaction (ORR), in which layered materials could possibly replace platinum. Although platinum offers both the lowest overpotential and the highest current density, it is also expensive and rare and has little tolerance to passivation. On the other hand, metal diborides are well known for their high chemical stability and low cost. Surprisingly, until now, only a few electrochemical properties of diborides have been studied. In this paper, we present the study of the electrocatalytic properties of metal borides (namely AlB2, CrB2, HfB2, MgB2, NbB2, TaB2, TiB2, VB2 and ZrB2) towards the HER and ORR together with their structural and chemical characterization.