钒-氮共掺杂碳基介孔纳米材料的制备及氮还原电催化性能

doi:10.11944/j.issn.1000-0518.2020.00.200037

摘要/Abstract

摘要： 电化学固氮技术由于可在温和条件下进行,为肥料低成本生产提供了新策略,但高稳定性和高活性电催化剂的选择是其关键技术。本文采用溶胶凝胶法合成了钒掺杂ZIF-8,以此为前驱体进一步高温碳化,合成了纳米介孔钒-氮共掺杂碳基电化学还原氮(NRR)催化剂。利用透射电子显微镜、X射线衍射、X光电子能谱和Raman光谱等对催化剂进行了表征分析。所得催化剂呈现出高度无序的三维多孔碳结构。催化剂中存在适量的V⁵⁺、碳化氮和吡啶氮对NRR起到明显促进作用。当前驱体中钒锌比为0.125,在N₂气气氛保护下1100 ℃热处理获得催化剂具有最佳NRR性能,在0.1 mol/L KOH电解质溶液中,当外加电压为-0.4 V时,氨的生产速率可达7.092 μmol/(cm²·h),法拉第效率为23.88%,且催化剂具有良好的稳定性。

关键词: 介孔碳, 钒氮共掺杂, 氮还原, 电催化

Abstract: Compared with the Haber-Bosch process, electrochemical nitrogen fixation can directly convert N₂ to NH₃ under mild environmental conditions, which is the building block of fertilizer for agricultural production. However, the screening of nitrogen reduction electrocatalyst with high activity and high stability is the most important. Here, vanadium doped ZIF-8 was synthesized by the sol-gel method, and used as the precursor to prepare mesoporous carbon electrochemical N₂ reduction reaction (NRR) catalysts at high temperature. The catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, etc. The catalyst shows a highly disordered three-dimensional carbon structure. The presence of appropriate amount of V⁵⁺, nitrogen carbide and pyridine nitrogen in the catalyst can promote NRR significantly. In the 0.1 mol/L KOH electrolyte solution, with V doped amount of 1/8 and the applied potential of -0.4 V, the catalyst has the best NRR performance at the calcination temperature of 1100 ℃. The ammonia production rate can reach 7.092 mol/(cm²·h) and the Faraday efficiency (FE%) is 23.88%. Meanwhile, its current density has a slight fluctuation at -0.4 V for 18 h electrochemical reaction, further suggesting that V-N co-doped carbon based mesoporous nanomaterials has high durability.

Key words: mesoporous carbon, V, N co-doping, N₂ reduction reaction, electrolysis

李琳, 任慧敏, 卫博慧, 李军, 王杰, 李晖, 姚陈忠. 钒-氮共掺杂碳基介孔纳米材料的制备及氮还原电催化性能[J]. 应用化学, 2020, 37(8): 930-938.

LI Lin, REN Huimin, WEI Bohui, LI Jun, WANG Jie, LI Hui, YAO Chenzhong. V-N Co-doped Mesoporous Carbon Nanomaterials as Catalysts for Artificial N₂ Reduction[J]. Chinese Journal of Applied Chemistry, 2020, 37(8): 930-938.

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