物理化学学报 >> 2021, Vol. 37 >> Issue (7): 2007079.doi: 10.3866/PKU.WHXB202007079

所属专题: 电催化

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双功能型嵌入镍纳米颗粒的碳棱柱状微米棒电极用于电化学甲醇氧化助力的节能产氢

吕琳, 张立阳, 何雪冰, 原弘, 欧阳述昕(), 张铁锐   

  • 收稿日期:2020-07-28 录用日期:2020-09-04 发布日期:2020-09-14
  • 通讯作者: 欧阳述昕 E-mail:oysx@mail.ccnu.edu.cn
  • 基金资助:
    the China Postdoctoral Science Foundation(2019M660184);the Natural Science Foundation of Hubei Province, China(2020CFB446);the National Natural Science Foundation of China(21972052);S.O. thanks the financial support from the "Guizi Scholar" Program of Central China Normal University, China

Energy-Efficient Hydrogen Production via Electrochemical Methanol Oxidation Using a Bifunctional Nickel Nanoparticle-Embedded Carbon Prism-Like Microrod Electrode

Lin Lv, Liyang Zhang, Xuebing He, Hong Yuan, Shuxin Ouyang(), Tierui Zhang   

  • Received:2020-07-28 Accepted:2020-09-04 Published:2020-09-14
  • Contact: Shuxin Ouyang E-mail:oysx@mail.ccnu.edu.cn
  • About author:Shuxin Ouyang. Email: oysx@mail.ccnu.edu.cn
  • Supported by:
    中国博士后科学基金(2019M660184);湖北省自然科学基金(2020CFB446);国家自然科学基金(21972052);华中师范大学“桂子学者”计划资助

摘要:

随着人类社会的高速发展,在保证环境不被破坏的情况下维持众多机械和电气设备的正常运转急需清洁的能源方式。氢被认为是在未来最有前景的清洁能源之一。近期,电化学水分解已被认为是获取氢能的最有效的方法之一,它的燃料产物只是无污染的水;然而,迟缓的析氧反应严重制约了水分解效率,导致驱动水分解的电压相对较高。探求热力学有利的阳极反应以取代缓慢的氧析出和开发高活性双功能型电催化剂用于这种阳极反应和析氢对于实现可应用于工业的节能型产氢至关重要。当前,普遍认为用其他有用的且利于热力学的反应取代析氧反应可以减小分解电压从而实现节能产氢。本文报道了一种用于甲醇氧化和析氢的双功能型嵌入镍纳米粒子的碳棱柱状微米棒电催化剂(命名为镍碳微米棒),该催化剂是由74号金属有机框架结构经碳化处理获得。这种由镍和碳构成的界面材料结构通过原位碳化实现,由于碳的分隔作用,分散的镍纳米颗粒不会轻易团聚,这有利于暴露更多的镍活性位点与电解液相接触,为更快的催化剂和电解液间电荷转移和电化学动力学提供保障。在此阳极的甲醇氧化中,产物分别为二氧化碳和甲酸,两者在1.55 V电压下的法拉第效率分别为36.2%和62.5%;同时该镍碳微米棒催化剂表现出优异的甲醇氧化活性和耐久性(12 h持续性催化,电流仅衰退2.7%)。值得注意的是,该双功能催化剂不仅具有甲醇氧化活性,在室温下含有0.5 mol∙L−1甲醇的1.0 mol∙L−1氢氧化钾电解液中的析氢过电位也较低(仅155 mV的过电位即可驱动10 mA∙cm−2的电流),保证了产氢效率。更重要的是,采用这种双功能型电极构造的双电极电解槽仅需1.6 V电压即可驱动10 mA∙cm−2的电流,与析氧反应作为阳极反应的电解槽相比驱动电压减小了240 mV。

关键词: 双功能, 析氢, 甲醇氧化, 镍纳米颗粒, 电解槽

Abstract:

With the rapid development of human society, clean energy forms are imperative to sustain the normal operations of various mechanical and electrical facilities under a cozy environment. Hydrogen is considered among the most promising clean energy sources for the future. Recently, electrochemical water splitting has been considered as one of the most efficient approaches to harvest hydrogen energy, which generates only non-pollutant water on combustion. However, the sluggish anodic oxygen evolution reaction significantly restricts the efficiency of water splitting and requires a relatively high cell voltage to drive the electrolysis. Therefore, seeking a thermodynamically favorable anodic reaction to replace the sluggish oxygen evolution reaction by utilizing highly active bifunctional electrocatalysts for the anodic reaction and hydrogen evolution are crucial for achieving energy-efficient hydrogen production for industrial applications. Nevertheless, it is known that the oxygen evolution reaction can be replaced with other useful and thermodynamically favorable reactions to reduce the electrolysis voltage for realizing energy-efficient hydrogen production. Therefore, in this study, we present a bifunctional nickel nanoparticle-embedded carbon (Ni@C) prism-like microrod electrocatalyst synthesized via a two-step method involving the synthesis of a precursor metal-organic framework-74 and subsequent carbonization treatment for methanol oxidation and hydrogen evolution. The interfacial structure consisting of a nickel and carbon skeleton was realized via in situ carbonization. However, the dispersed nickel nanoparticles do not easily aggregate owing to the partition by the surrounding carbon as it would sufficiently expose the active Ni sites to the electrolytes, ensuring fast charge transfer between the catalyst and electrolytes by accelerating the electrochemical kinetics. In the anodic methanol oxidation, the products were detected as carbon dioxide and formate with faradaic efficiencies of 36.2% and 62.5%, respectively, at an applied potential of 1.55 V. Meanwhile, the Ni@C microrod catalyst demonstrated high activity and durability (2.7% current decay after 12 h of continuous operation) toward methanol oxidation, which demonstrates that methanol oxidation precedes oxidation under voltage forces. Notably, the bifunctional catalyst not only exhibits excellent performance toward methanol oxidation but also yields a low overpotential of 155 mV to drive 10 mA∙cm−2 toward hydrogen evolution in 1.0 mol∙L−1 KOH aqueous solution with 0.5 mol∙L−1 methanol at room temperature, which guarantees the hydrogen production efficiency. More importantly, the constructed two-electrode electrolyzer produced a current density of 10 mA∙cm−2 at a low cell voltage of 1.6 V, which decreased by 240 mV after replacing the oxygen evolution reaction with methanol oxidation.

Key words: Bifunctionality, Hydrogen evolution, Methanol oxidation, Nickel nanoparticles, Electrolyzer

MSC2000: 

  • O646