NiN_(4)/Cr修饰的石墨烯电化学固氮电极

NiN_(4)/Cr Embedded Graphene for Electrochemical Nitrogen Fixation

工业上应用哈伯工艺法合成氨过程要求严苛,需要消耗大量能源且二氧化碳排放量大。因此,开发在常规环境条件下通过电催化氮还原反应的清洁技术,对未来可持续的能源转化进程具有重要意义。本研究采用密度泛函理论计算方法,对TM_(1)N_(4)/TM_(2)嵌入石墨烯的氮还原反应进行了全面研究。在充分考虑活性和稳定性的情况下,研究结果表明,NiN_(4)/Cr锚定石墨烯通过酶促反应途径表现出最佳的催化活性,其中第一次加氢为电位决定步骤,起始电位为0.57 V,优于商业Ru基材料。此外,与单一的Cr原子修饰的石墨烯相比,引入NiN_(4)官能团降低了ΔG_(max)并提高了电催化性能。根据Mulliken电荷分析,催化剂的催化活性主要来源于载体和反应中间体之间的电子转移。上述结果为高效合成氨提供了电极候选材料,进一步深化了相应的电催化机理。

Owing to the heavy energy consumption and the massive CO_(2) emission during ammonia synthesis via Haber-Bosch process,a clean technology of nitrogen reduction electrocatalysis under ambient conditions is of significance for the sustainable energy conversion progress in future.In the study,the nitrogen reduction reaction of TM_(1)N_(4)/TM_(2) embedded graphene is comprehensively investigated using density functional theory calculations.Fully considering the activity and stability,our results reveal that NiN_(4)/Cr anchored graphene exhibits the best catalytic activity via the enzymatic reaction pathway wherein the potential determining step is located at the first hydrogenation with an onset potential of 0.57 V,being superior to the commercial Ru-based material.Furthermore,compared with the isolated Cr atom decorated nitrogen functionalized graphene,the introduction of NiN_(4) moiety decreases ΔG_(max) and enhances the electrocatalytic performance.According to the Mulliken charge analysis,the physical origin of the catalytic activity is ascribed to the electron transition between the supports and reaction intermediates.Overall,these results pave a way for the design of the high efficient electrode material for ammonia synthesis and provide a fundamental insight into the electrocatalysis.