Precursor-based synthesis and electrochemical nitrogen reduction reaction (eNRR) activity of compositionally complex early transition metal carbides and (carbo)nitrides

Abstract

Compositionally complex carbides and carbonitrides, incorporating multiple transition metals into a single-phase lattice, have emerged as promising candidates for advanced applications, including ultra-high-temperature ceramics, hard coatings, and heterogeneous catalysis. However, precursor-based synthesis routes for these materials remain underexplored, limiting access to tailored compositions and microstructures. Here, we report the successful synthesis of single-phase rock salt-type (V, Nb, Ta, Mo, W)C and related multi-cationic (carbo)nitrides via a dibenzoylmethane-assisted, non-aqueous precursor route followed by pyrolysis at temperatures as low as 1000 °C. Structural and morphological analyses confirm phase homogeneity and the critical role of Ta in stabilizing the rock salt structure. For the first time, the electrochemical nitrogen reduction reaction (eNRR) activity of these compositionally complex ceramics was investigated. Notably, (VNbTaMoW)C<inf>0.87</inf>O<inf>0.11</inf> achieves an ammonia yield of 109 µg h⁻¹ mg<inf>cat</inf>⁻¹, outperforming binary and ternary analogues, whereas nitride-based catalysts show higher faradaic efficiencies but lower yields. The findings of the presented study demonstrate that compositional complexity offers new opportunities for catalyst design in sustainable ammonia synthesis and establish precursor-based synthesis as a versatile route for accessing advanced multi-principal ceramics for energy conversion and beyond.