In the field of nitrogen electroreduction reaction (NRR), the most competing side reaction is known to be the hydrogen evolution reaction (HER) that can compromise both the reaction rate and faradaic efficiency towards NRR. With the use of Density Functional Theory (DFT) calculations, we have conducted a comprehensive screening over a wide range of transition metal nitride (TMN) surfaces as cathode catalyst to find which nitride favours NRR and which favours the HER. The findings of our modelling revealed that earlier TMNs (ScN, TiN, YN, HfN, and TaN) were expected to favour HER, while VN, CrN, ZrN, and NbN were predicted to favour NRR. However, the nitrides of later transition metals (Fe, Co, Ni, Cu, Rh, Pd, Ag, Ir, and Pt) were found to be unstable and reduced to their parental metals over the course of the reaction. We then carried out comprehensive investigations of these different nitrides toward both NRR and HER via DFT calculations and nominated the (100) facets of the rocksalt structure of TaN as the most promising nitride for HER^1,2. For NRR, the (100) facets of the rocksalt structures of VN, ZrN, and NbN were predicted to be more interesting for NRR^3–8.

References:

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