Antiperovskite Nitrides as Efficient and Durable Electrocatalysts for Industrially Relevant Hydrogen Evolution

Phase-pure antiperovskite nitrides (A 3 XN; A = Co, Ni; X = Zn, In, Sn) synthesized via a melamine method were evaluated as cost-effective, high-performance hydrogen evolution reaction (HER) electrocatalysts. Initial tests in 1 M NaOH electrolyte revealed limited activity, significantly enhanced by reductive electrochemical cycling, attributed to the in situ formation of catalytically active zero-valent Co 0 and Ni 0 surface species. Comparative studies of isostructural Fe-based nitrides confirmed that these metallic A-site species constitute the active sites. Accelerated stability tests (95 °C, 10 M NaOH) identified Co 3 ZnN and Ni 3 ZnN as particularly robust, maintaining intact antiperovskite structures and high catalytic activity (>70 mA cm –2 after 210 h). Partial substitution (Zn for In) further improved stability, notably for Ni 3 Zn 0.25 In 0.75 N. This study highlights the crucial role of compositional tuning and surface activation in optimizing HER performance, emphasizing that systematic stability assessments under industrially relevant conditions (high temperature, concentrated electrolyte) are essential. Antiperovskite nitrides thus offer promising avenues for scalable, green hydrogen production technologies.