Metal nitrides are widely studied due to their outstanding physical properties, including high hardness, high thermal and chemical stability, low electrical resistivity etc. Generally, metal nitrides can be obtained from the direct reaction of metal and ammonia/nitrogen. However, some of the metal nitrides, such as Ta₃N₅, cannot be synthesized by direct nitridation of metals. To achieve Ta₃N₅, high-oxidation-state Ta precursors like Ta₂O₅, NaTaO₃, TaS₃, K₆Ta_10.8O₃₀, Ta(N(CH₃)₂)₅ and TaCl₅ have to be employed, which is a time-consuming and laborious process with the possibility of introducing undesirable impurities. Here taking Ta₃N₅ as an example, a facile carbonate-assisted one-step nitridation method is proposed, which enables the direct synthesis of high-oxidation-state metal nitride films from metal precursors under ammonia flow. The mechanism of the nitridation process has been studied, which carbon dioxide released from carbonates decomposition reacts with metallic Ta and assists the one-step conversion of metallic Ta to Ta₃N₅. The as-prepared Ta₃N₅ film, after modified with NiFe layered double hydroxide, exhibits promising water splitting performance and stability. This method avoids the preoxidation process of metal precursors in high-oxidation-state metal nitride synthesis, and may facilitate the direct fabrication of other important metal nitrides besides Ta₃N₅.

金属氮化物由于其优异的物理性能而被广泛研究，包括高硬度、高热稳定性和化学稳定性、低电阻率等。通常，金属氮化物可以通过金属和氨/氮的直接反应获得。然而，一些金属氮化物，例如Ta ₃ N ₅，不能通过金属的直接氮化合成。为了获得 Ta ₃ N ₅，高氧化态 Ta 前体，如 Ta ₂ O ₅、NaTaO ₃、TaS ₃、K ₆ Ta _10.8 O ₃₀、Ta(N(CH ₃ ) ₂ ) ₅必须使用TaCl ₅，这是一个费时费力的过程，并可能引入不需要的杂质。这里以 Ta ₃ N ₅为例，提出了一种简便的碳酸盐辅助一步氮化方法，该方法能够在氨流下从金属前驱体直接合成高氧化态金属氮化物薄膜。研究了氮化过程的机理，碳酸盐分解释放的二氧化碳与金属Ta发生反应，并协助金属Ta一步转化为Ta ₃ N ₅。所制备的 Ta ₃ N ₅用NiFe层状双氢氧化物改性后的薄膜表现出良好的水分解性能和稳定性。该方法避免了高氧化态金属氮化物合成中金属前驱体的预氧化过程，有利于直接制备除Ta ₃ N ₅之外的其他重要金属氮化物。