Overcoming coke formation in high-temperature CO_(2)electrolysis  

克服高温二氧化碳电解产生的碳沉积问题

作　　者：Tongbao Wang Guangtai Han Ziyun Wang Yuhang Wang 王同宝;韩光泰;王子运;王昱沆(苏州大学功能纳米与软物质研究院,江苏省碳基功能材料与器件重点实验室,中国江苏苏州215123;奥克兰大学化学科学学院,新西兰)

机构地区：[1]Institute of Functional Nano&Soft Materials(FUNSOM),Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices,Soochow University,Suzhou 215123,Jiangsu,China [2]School of Chemical Sciences,University of Auckland,Auckland 1010,New Zealand

出　　处：《Chinese Journal of Catalysis》2022年第12期2938-2945,共8页催化学报（英文）

基　　金：国家自然科学基金(2219088);江苏省自然科学基金(BK20210699).

摘　　要：High-temperature CO_(2)reduction reaction(HT-CO_(2)RR)in solid oxide electrochemical cells(SOECs)features near-unity selectivity,high energy efficiency,and industrial relevant current density for the production of CO,a widely-utilized“building block”in today’s chemical industry.Thus,it offers an intriguing and promising means to radically change the way of chemical manufacturing and achieve carbon neutrality using renewable energy sources,CO_(2),and water.Albeit with the great potential of HT-CO_(2)RR,this carbon utilization approach,unfortunately,has been suffering coke formation that is seriously detrimental to its energy efficiency and operating lifetime.In recent years,much effort has been added to understanding the mechanism of coke formation,managing reaction conditions to mitigate coke formation,and devising coke-formation-free electrode materials.These investigations have substantially advanced the HT-CO_(2)RR toward a practical industrial technology,but the resulting coke formation prevention strategies compromise activity and energy efficiency.Future research may target exploiting the control over both catalyst design and system design to gain selectivity,energy efficiency,and stability synchronously.Therefore,this perspective overviews the progress of research on coke formation in HT-CO_(2)RR,and elaborates on possible future directions that may accelerate its practical implementation at a large scale.固体氧化物电解池(SOEC)中的高温二氧化碳电还原(HT-CO_(2)RR)具有对产物CO选择性近乎100%、能量效率高且产率可达到工业标准等特点.该技术能够将可再生能源、二氧化碳和水转化成高能量化合物,是实现碳中和的有效途径,具有较强的应用前景.但这种二氧化碳利用方法容易受电解过程中的积碳影响,严重损害电解池的能量效率和运行寿命.近年来,研究者们努力分析积碳问题,并通过改变反应条件来抑制积碳生成,或尝试设计无积碳产生的电极材料.然而,这些抑制积碳的策略同时牺牲了催化活性和能量效率.因此,未来研究需要兼顾催化电极的性能、电解池的能量效率和稳定性.本文概述了关于减少HT-CO_(2)RR中积碳的研究进展,讨论可能加速其大规模实际应用的未来研究方向,并阐述了SOEC的HT-CO_(2)RR中积碳的形成机制.HT-CO_(2)RR中积碳的形成是由于CO发生了歧化反应:2CO(g)⇌C+CO_(2)(g),也被称为Boudouard反应.该反应涉及两个基本步骤:(1)表面CO^(*)解离为C^(*)和O^(*),(2)表面CO^(*)和O^(*)耦合形成CO_(2)^(*).整个反应受CO^(*),C^(*),O^(*)和CO_(2)^(*)表面覆盖率影响,高CO^(*)和C^(*)覆盖率推动反应向积碳生成的方向进行,而高CO_(2)^(*)和O^(*)覆盖率则有利于逆反应发生.Ni通常被认为是HT-CO_(2)RR中Boudouard反应的催化剂.密度泛函理论(DFT)研究发现,较低的CO解离(即CO^(*)+^(*)→C^(*)+O^(*))势垒和较强的C吸附能可能会导致高表面C^(*)覆盖率,促进积碳生成.因此,与具有高配位数的Ni(111)表面相比,具有较低配位数的Ni(211)表面更容易使HT-CO_(2)RR反应过程发生积碳.同时,由于SOEC中的CO解离涉及来自外部电路的电子转移,从而使C从+2价降低到0价,施加阴极偏压会进一步降低CO解离的反应势垒和自由能.但前期的实验和模拟表明,在多数情况下,系统中的CO化学歧化更可能是HT-CO_(2)RR中积碳形成的主要原因.但也有部�

关 键 词：High-temperature CO_(2)electroreduction Solid oxide electrochemical cell Coke formation Boudouard reaction STABILITY 

分 类 号：O646[理学—物理化学] O643.36[理学—化学]