Although I am working on making catalysts for homogeneous catalysis, one of my biggest passions is heterogeneous catalysis.
Metal nitrides are one of the most interesting class of these catalysts. There are several examples of them used and being explored in ammonia synthesis, hydrotreating, hydrogenation and so on. There are examples of these in this paper. You can also read several different methods to make these catalysts and some distinctive features of each.
There is a nice paragraph summarizing the limitations of the experiments and analysis of these catalysts too such as surface structure-activity reaction.
For those who know nothing about metal nitrides in heterogeneous catalysis, I think the key is that they are believed to show "noble-metal like behaviour."