Cui Luyao, Sun Zijun, Wang Yawen, Jian Xuan, Li Houfen, Zhang Xiao, Gao Xiaoming, Li Rui, Liu Jianxin
Key Laboratory of Coal Science and Technology Ministry of Education, College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China.
Xi'an North Huian Chemical Industries Co. Ltd, Xi'an 710302, Shaanxi, China.
Phys Chem Chem Phys. 2024 May 29;26(21):15705-15716. doi: 10.1039/d4cp01207k.
The electrochemical NH synthesis on TiNO is proposed to follow the Mars-van Krevelen (MvK) mechanism, offering more favorable N adsorption and activation on the N vacancy (Nv) site, compared to the conventional associative mechanism. The regeneration cycle of Nv represents the rate-determining step in this process. This study investigates a series of TM (Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt)-TiNO to explore the *H migration (from TM to TiNO)-promoted Nv cycle. The screening results indicate that Ni-TiNO exhibits strong HO decomposition for *H production with 0.242 eV and low *H migration resistance with 0.913 eV. Notably, *H migration from Ni to TiNO significantly reduces the Nv formation energy to 0.811 eV, compared to 1.387 eV on pure TiNO. Meanwhile, in the presence of *H, Nv formation takes precedence over Tiv and Ov. Lastly, electronic performance calculations reveal that the collaborative function provided by Ni and Nv enables highly stable and efficient NH synthesis. The *H migration-assisted MvK mechanism demonstrates effective catalytic cycle performance in electrochemical N fixation and may have potential applicability to other hydrogenation reactions utilizing water as a proton source.
据推测，TiNO上的电化学氨合成遵循Mars-van Krevelen（MvK）机制，与传统的缔合机制相比，该机制在氮空位（Nv）位点上提供了更有利的氮吸附和活化。Nv的再生循环是该过程中的速率决定步骤。本研究考察了一系列TM（铁、钴、镍、钌、铑、钯、锇、铱和铂）-TiNO，以探索H迁移（从TM到TiNO）促进的Nv循环。筛选结果表明，Ni-TiNO表现出很强的H分解产*H能力，分解能为0.242 eV，*H迁移阻力低，为0.913 eV。值得注意的是，与纯TiNO上的1.387 eV相比，H从Ni迁移到TiNO显著降低了Nv形成能，降至0.811 eV。同时，在有H存在的情况下，Nv的形成优先于Tiv和Ov。最后，电子性能计算表明，Ni和Nv提供的协同作用使氨合成具有高度稳定性和高效性。*H迁移辅助的MvK机制在电化学固氮中表现出有效的催化循环性能，可能对其他以水为质子源的加氢反应具有潜在的适用性。
