基于非贵金属催化剂常温常压电化学合成氨

氨是一种重要的化工原料和能量载体,“哈伯反应”是工业上合成氨最主要的方法,但是该方法存在着能耗高,大量排放温室气体CO₂以及转化率低等问题。近年来,常温常压下基于多相催化剂的电化学还原N₂反应(NRR)来制备氨因其原料(N₂ + H₂O)易得,不依赖传统化石能源以及条件温和等原因而表现出巨大的应用潜能,并受到了科学家的广泛关注。然而目前NRR仍存在着如催化剂以贵金属材料为主,催化效率低和催化机理未明确等问题亟待解决。本综述主要总结了电催化NRR的最新研究成果,首先介绍了电催化NRR热力学和催化机理,接着重点列举了基于非贵金属催化剂的研究进展,包括过渡金属氧化物、氮化物、硫化物、非金属催化剂及单原子催化剂等,然后讨论了几种NRR电催化剂的改性方法,以及常见的产物氨的定性定量方法,最后,就目前该研究方向中仍待解决的问题进行了总结,并对下一步的研究进行了展望。

Electroreduction of Nitrogen to Ammonia Catalyzed by Non-Noble Metal Catalysts under Ambient Conditions

Ammonia is an important chemical for producing fertilizer and also an important carbon-free energy carrier.Haber-Bosch process is the main method to synthesize ammonia.However,it suffers from some severe problems,such as the high energy consumption,the massive emission of greenhouse gas CO2 and the poor catalytic efficiency.Recently,ammonia synthesis based on electrocatalytic nitrogen reduction reaction(NRR) by using renewable energy under mild reaction conditions has attracted wide research attention.In addition,the raw materials(N2+H2 O) are earth abundant.Although great advances have been achieved in electro catalytic NRR field,some challenges including the high-cost of noble metal based electro catalysts,the low ammonia yield and unsatisfactory Faradaic efficiency,as well as the unexplored catalytic mechanism of NRR still exist.In this review,we summarize the recent advances in electro catalytic NRR field based on heterogeneous catalysts.Firstly,we discuss the catalytic thermodynamics and reaction mechanisms towards NRR.Secondly,a range of recently reported non-noble metal included catalysts are surveyed,including transition metal oxides/nitrides/sulfides,metal-free materials and single-metal-atom catalysts.Then,some promising strategies to enhance the catalytic activity,selectivity and efficiency are proposed,and the main methods for the determination of ammonia are also mentioned.Finally,the challenges remaining to be solved are summarized,and future perspectives are also presented.