具有丰富晶界的铜催化剂在气-液平衡扩散电极上高效电还原CO_(2)制C_(2)H_(4)  

Grain boundary‐abundant copper nanoribbons on balanced gas‐liquid diffusion electrodes for efficient CO_(2) electroreduction to C_(2)H_(4)

作　　者：卞磊 张紫阳 田昊 田娜娜 马智[1] 王中利 Lei Bian;Zi-Yang Zhang;Hao Tian;Na-Na Tian;Zhi Ma;Zhong-Li Wang(Tianjin Key Laboratory of Applied Catalysis Science&Technology,School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学化工学院,天津市应用催化科学与工程重点实验室,天津300072

出　　处：《Chinese Journal of Catalysis》2023年第11期199-211,共13页催化学报（英文）

基　　金：国家自然科学基金(22075201);国家重点研发计划(2022YFB4101800).

摘　　要：电催化二氧化碳还原反应(CO_(2)RR)可以将二氧化碳转化为具有高经济价值的碳氢化合物,被认为是实现碳中和并缓解能源危机的一种有潜力的技术.铜(Cu)作为一种最有应用前景的非贵金属催化剂之一,表现出较高的催化CO_(2)RR转化为多碳产物(C_(2+))的活性.然而,电催化CO_(2)还原成C_(2+)产物涉及一个动力学过程缓慢的C-C偶联反应,这导致C_(2+)产物的选择性较低,电流密度低,阻碍了其在工业电解槽中的实际应用.同时,CO_(2)RR产物的选择性不仅取决于热力学速率决定步骤,还取决于传质控制动力学.CO_(2)RR发生在固-气-液三相反应界面,气-液的平衡扩散可以有效抑制析氢竞争反应,进而提高CO_(2)RR的反应效率.本文设计合成了一种富晶界的Cu纳米带催化剂,并构建了气-液平衡扩散的电极结构,用于高效电催化二氧化碳还原制备乙烯(C_(2)H_(4)).以一种碱式碳酸铜(Cu_(2)CO_(3)(OH)_(2))纳米带为前驱体,在原位电化学还原条件下,前驱体中的Cu2+离子获得电子被还原为金属Cu,而释放的CO_(3)2-和OH-混合阴离子调节金属Cu的生长.生成的Cu纳米带由细小的纳米颗粒堆积而成,并暴露出大量的由Cu(111),Cu(200)和Cu(220)晶面形成的富晶界结构(GBs).同时,在CO_(2)RR测试中发现催化剂层的厚度是影响CO_(2)和电解质传质的关键因素.通过调整催化层厚度,CO_(2)和电解质可以同时到达催化剂表面,参与到CO_(2)RR中,实现了气-液平衡扩散,有效抑制了氢析出副反应.在晶界效应和气-液平衡扩散的协同作用下,优化后的电极在电流密度为700 mA cm^(-2)时,对C_(2)H_(4)和C_(2+).产物的法拉第效率分别高达67.2%和82.1%.此外,C_(2)H_(4)的部分电流密度可高达505 mA cm^(-2),高于大多数文献报道的结果.原位拉曼光谱和衰减全内反射表面增强红外吸收光谱结果表明,丰富的晶;界结构增强了CO_(2)在催化剂表面的活化,显著促进了*CO中间体的形�The electrocatalytic CO_(2) reduction reaction(CO_(2)RR)is a promising technology to produce value-added hydrocarbon chemicals,however,achieving a high selectivity to C_(2+)products at the industrial current density remains a great challenge.Herein,we demonstrate grain boundary-abundant copper(Cu)nanoribbons on balanced gas-liquid diffusion electrodes for efficient CO_(2)RR to ethylene(C_(2)H_(4)).The Cu(II)carbonate basic(Cu_(2)CO_(3)(OH)_(2))nanoribbon is used as a precursor to convert into metal Cu under in situ electrochemical reduction.Unexpectedly,the generated Cu nanoribbon is formed by stacking tiny nanoparticles with exposure of Cu(111),Cu(200)and Cu(220)facets,which creates abundant grain boundaries(GBs).During CO_(2)RR test,the thickness of the catalyst layer is identified as a crucial factor for the mass transfer of CO_(2) and electrolyte.By tailoring the thickness of catalytic layer,CO_(2) and electrolyte can simultaneously reach the surface of catalyst and participate in CO_(2)RR.Under the synergetic effects of GBs and balanced gas-liquid diffusion,the optimized electrode delivers the Faradaic efficiencies toward C_(2)H_(4)and C_(2+)products as high as 67.2%and 82.1%at the current density of 700 mA cm^(-2) ,respectively.Moreover,the partial current density of C_(2)H_(4)can reach up to 505 mA cm^(-2) ,which is significantly higher than most reported results.The in situ Raman and attenuated total reflection surface-enhanced infrared absorption spectra show that abundant GBs enhance the activation of CO_(2) and significantly promote the formation and adsorption of*CO intermediates,which accelerate C-C coupling to form*OCCO and*OCCOH intermediates and improve the production of C_(2)H_(4)and other C_(2+)products.

关 键 词：电催化二氧化碳还原 乙烯 C_(2+)产物 晶界 气-液扩散 

分 类 号：O64[理学—物理化学]