Mechanistic Insights into Electrochemical Nitrogen Reduction Reaction on Vanadium Nitride Nanoparticles
Mechanistic Insights into Electrochemical Nitrogen Reduction Reaction on Vanadium Nitride Nanoparticles
复制标题
DOI：
10.1021/jacs.8b08379
复制
发表时间：
2018-10-17
影响因子：
15
通讯作者：
Xu, Bingjun
中科院分区：
文献类型：
--
作者：
Yang, Xuan;Nash, Jared;Xu, Bingjun
通过电化学氮还原反应（ENRR）可再生地生产氨（大多数肥料的组成部分）是可取的；然而，缺乏选择性电催化剂。在这里，我们表明，氮化钒（VN）纳米颗粒是一种活性、选择性和稳定的ENRR催化剂，在-0.1 V下1小时内的ENRR速率和法拉第效率（FE）分别为3.3 X 10(-10) mol s(-1) cm(-2)和6.0%。以 N-15(2) 作为进料的 ENRR 生成 (NH3)-N-14 和 (NH3)-N-15，这表明该反应遵循 Mars-van Krevelen 机理。新鲜和废催化剂的异位 X 射线光电子能谱表征表明，表面存在多种氧化钒、氮氧化物和氮化物物质，并确定 VN0.7O0.45 为 ENRR 中的活性相。 Operando X射线吸收光谱和催化剂耐久性测试结果证实了这一假设，并表明VN0.7O0.45向VN相的转化导致催化剂失活。我们假设只有与表面 O 相邻的表面 N 位点在 ENRR 中具有活性。 1.1 X 10(-10) mol s(-1) cm(-2)的氨产率可维持116 h，稳态周转数为431。
Renewable production of ammonia, a building block for most fertilizers, via the electrochemical nitrogen reduction reaction (ENRR) is desirable; however, a selective electrocatalyst is lacking. Here we show that vanadium nitride (VN) nanoparticles are active, selective, and stable ENRR catalysts with an ENRR rate and a Faradaic efficiency (FE) of 3.3 X 10(-10) mol s(-1) cm(-2) and 6.0% at -0.1 V within 1 h, respectively. ENRR with N-15(2) as the feed produces both (NH3)-N-14, and (NH3)-N-15, which indicates that the reaction follows a Mars-van Krevelen mechanism. Ex situ X-ray photoelectron spectroscopy characterization of fresh and spent catalysts reveals that multiple vanadium oxide, oxynitride, and nitride species are present on the surface and identified VN0.7O0.45 as the active phase in the ENRR. Operando X-ray absorption spectroscopy and catalyst durability test results corroborate this hypothesis and indicate that the conversion of VN0.7O0.45 to the VN phase leads to catalyst deactivation. We hypothesize that only the surface N sites adjacent to a surface O are active in the ENRR. An ammonia production rate of 1.1 X 10(-10) mol s(-1) cm(-2) can be maintained for 116 h, with a steady-state turnover number of 431.