Tuning the intermediate reaction barriers by a CuPd catalyst to improve the selectivity of CO_(2) electroreduction to C_(2) products  

CuPd催化剂调节中间反应能垒提高电催化CO_(2)生成二碳产物的选择性

作　　者：Li Zhu Yiyang Lin ang Liu Emiliano Cortés Hongmei Li Junhua Hu Akira Yamaguchi Xiaoliang Liu Masahiro Miyauchi Junwei Fu Min Liu 朱莉;林翌阳;刘康;Emiliano Cortés;李红梅;胡俊华;Akira Yamaguchi;刘小良;Masahiro Miyauchi;傅俊伟;刘敏(中南大学物理与电子学院,湖南长沙410083;慕尼黑大学物理学院,慕尼黑,德国;郑州大学材料科学与工程学院,河南郑州450052;东京工业大学材料与化工技术学院,材料与科学工程系,东京,日本)

机构地区：[1]Shenzhen Research Institute,School of Physics and Electronics,Central South University,Changsha 410083,Hunan,China [2]Chair in Hybrid Nanosystems,Nanoinstitute Munich,Faculty of Physics,Ludwig‐Maximilians‐Universität München,80539 München,Germany [3]School of Materials Science and Engineering,Zhengzhou University,Zhengzhou 450052,Henan,China [4]Department of Materials Science and Engineering,School of Materials and Chemical Technology,Tokyo Institute of Technology,Tokyo 152‐8552,Japan

出　　处：《Chinese Journal of Catalysis》2021年第9期1500-1508,共9页催化学报（英文）

基　　金：国家自然科学基金(21872174,22002189,51673217,U1932148);国家科技部重点研发国际间合作项目(2017YFE0127800,2018YFE 0203402);湖南省科技计划项目(2017XK2026);湖南省自然科学基金(2020JJ2041,2020JJ5691),湖南省科技计划项目(2017TP1001);深圳科技创新项目(JCYJ20180307151313532)。

摘　　要：Electrochemical CO2 reduction is a promising strategy for the utilization of CO2 and intermittent excess electricity.Cu is the only single metal catalyst that can electrochemically convert CO2 into multicarbon products.However,Cu exhibits an unfavorable activity and selectivity for the generation of C2 products because of the insufficient amount of CO*provided for the C‐C coupling.Based on the strong CO2 adsorption and ultrafast reaction kinetics of CO*formation on Pd,an intimate CuPd(100)interface was designed to lower the intermediate reaction barriers and improve the efficiency of C2 product formation.Density functional theory(DFT)calculations showed that the CuPd(100)interface enhanced the CO2 adsorption and decreased the CO2*hydrogenation energy barrier,which was beneficial for the C‐C coupling.The potential‐determining step(PDS)barrier of CO2 to C2 products on the CuPd(100)interface was 0.61 eV,which was lower than that on Cu(100)(0.72 eV).Encouraged by the DFT calculation results,the CuPd(100)interface catalyst was prepared by a facile chemical solution method and characterized by transmission electron microscopy.CO2 temperature‐programmed desorption and gas sensor experiments further confirmed the enhancement of the CO2 adsorption and CO2*hydrogenation ability of the CuPd(100)interface catalyst.Specifically,the obtained CuPd(100)interface catalyst exhibited a C2 Faradaic efficiency of 50.3%±1.2%at‒1.4 VRHE in 0.1 M KHCO3,which was 2.1 times higher than that of the Cu catalyst(23.6%±1.5%).This study provides the basis for the rational design of Cu‐based electrocatalysts for the generation of multicarbon products by fine‐tuning the intermediate reaction barriers.过度的碳排放已造成了严重的全球环境问题,电催化CO_(2)还原是一种利用间歇性过剩电能将CO_(2)转化为有价值的化学物质的有效策略.在多种CO_(2)还原产物中,二碳(C2)产物(如乙烯、乙醇)因其比一碳产物(如甲酸、甲烷、甲醇)具有更高的能量密度而备受关注.Cu是唯一能用电化学方法将CO_(2)转化为多碳产物的单金属催化剂.如何提高Cu基催化剂上CO_(2)还原为C2产物的效率已引起了极大关注.电催化还原CO_(2)生成C2产物有两个重要步骤:一是参与碳碳偶联反应的CO*中间体的量(*代表中间体吸附在基底表面),二是碳碳偶联步骤的能垒.对于Cu单金属催化剂,虽然其表面碳碳偶联步骤的能垒相对较低,但是Cu对CO_(2)的吸附能力和CO_(2)*加氢能力并不高,导致在Cu表面不能生成足量的CO*中间体参与碳碳偶联反应,因而对C2产物的选择性和活性并不理想.与Cu单金属催化剂相反,在Pd单金属催化剂表面,CO*中间体的形成具有超快的反应动力学,但是CO*易在Pd表面中毒且后续碳碳偶联步骤的能垒极高,使其表面不能生成C2产物.为了充分发挥Cu(碳碳偶联步骤能垒较低)和Pd(CO*形成具有超快反应动力学)的双重优势,本文构建了一种紧密的CuPd(100)界面,以调节中间反应能垒,从而提高C2产率.密度泛函理论(DFT)计算表明,CuPd(100)界面增强了CO_(2)的吸附,且降低了CO_(2)*加氢步骤的能垒,从而能够催化生成更多的CO*中间体参与碳碳偶联反应.且CuPd(100)界面上CO_(2)还原为C2产物的电位决定步骤能垒为0.61 eV,低于Cu(100)表面的(0.72 eV).本文采用了一种简便的湿化学法制备了CuPd(100)界面催化剂.X射线衍射和X射线光电子能谱测试以及扩展X射线吸收精细结构光谱结果表明,合成的是相分离的CuPd双金属催化剂,而非CuPd合金催化剂.同时高分辨透射电镜可以观察到清晰的CuPd(100)界面.由此可见,本文成功合成了CuPd(100)界面�

关 键 词：Carbon dioxide reduction C2 products ELECTROCATALYST Copper‐palladium interface Intermediate reaction barriers 

分 类 号：TQ207[化学工程—有机化工] TQ426