Understanding the C-C coupling mechanism in electrochemical CO reduction at low CO coverage:Dynamic change in site preference matters  

电化学CO还原中低CO覆盖度下的C-C偶联机制:反应物种最稳定吸附构型随电位的动态变化

作　　者：Zhe Chen Tao Wang 陈哲;王涛(浙江大学化学系,浙江杭州310027;西湖大学人工光合作用与太阳能燃料中心,化学系,未来产业研究中心,浙江杭州310030;浙江西湖高等研究院理学研究所,浙江杭州310024;浙江省白马湖实验室,太阳能转换与催化西湖大学基地,浙江杭州310000)

机构地区：[1]Department of Chemistry,Zhejiang University,Hangzhou 310027,Zhejiang,China [2]Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry,School of Science and Research Center for Industries of the Future,Westlake University,Hangzhou 310030,Zhejiang,China [3]Institute of Natural Sciences,Westlake Institute for Advanced Study,Hangzhou 310024,Zhejiang,China [4]Division of Solar Energy Conversion and Catalysis at Westlake University,Zhejiang Baima Lake Laboratory Co.,Ltd.,Hangzhou 310000,Zhejiang,China

出　　处：《Chinese Journal of Catalysis》2025年第2期193-202,共10页催化学报(英文)

基　　金：国家重点研发计划(2022YFA0911900);国家自然科学基金(22273076);西湖大学和西湖大学未来产业研究中心的科研启动项目.

摘　　要：A thoroughly mechanistic understanding of the electrochemical CO reduction reaction(eCORR)at the interface is significant for guiding the design of high-performance electrocatalysts.However,unintentionally ignored factors or unreasonable settings during mechanism simulations will result in false positive results between theory and experiment.Herein,we computationally identified the dynamic site preference change of CO adsorption with potentials on Cu(100),which was a previously unnoticed factor but significant to potential-dependent mechanistic studies.Combined with the different lateral interactions among adsorbates,we proposed a new C–C coupling mechanism on Cu(100),better explaining the product distribution at different potentials in experimental eCORR.At low potentials(from–0.4 to–0.6 V_(RHE)),the CO forms dominant adsorption on the bridge site,which couples with another attractively aggregated CO to form a C–C bond.At medium potentials(from–0.6 to–0.8 VRHE),the hollow-bound CO becomes dominant but tends to isolate with another adsorbate due to the repulsion,thereby blocking the coupling process.At high potentials(above–0.8 VRHE),the CHO intermediate is produced from the electroreduction of hollow-CO and favors the attraction with another bridge-CO to trigger C–C coupling,making CHO the major common intermediate for C–C bond formation and methane production.We anticipate that our computationally identified dynamic change in site preference of adsorbates with potentials will bring new opportunities for a better understanding of the potential-dependent electrochemical processes.电化学二氧化碳还原为碳基燃料和化学品为碳中和提供了一条有前景的途径.铜是可以电催化驱动生产多碳产物中性能较好的金属电极.其中,CO被认为是C-C键形成的关键中间体,但其偶联机制仍具争议.因此,深入理解界面处的电化学C-C键形成机制对于高性能电催化剂的设计具有重要意义.而在过去的机理模拟过程中,忽略了一些因素或不合理的假设,这可能会导致理论和实验之间出现假阳性结果.例如:(1)忽略了电化学条件下CO吸附位点偏好随电位动态变化的可能性;(2)通常将两个CO分子默认地放置在一个小的表面模型中,这会导致与实验不相符的高CO覆盖度.本文采用具有混合溶剂化模型的恒电位计算,重新研究了Cu(100)表面在低CO覆盖度下电化学CO还原反应中的电位依赖的C-C偶联机制首先,通过比较CO分子在Cu(100)三种吸附位点(顶位、桥位和四配位)上的电位依赖吸附自由能发现:随着外接电位逐渐降低,CO的最稳定吸附位点会渐变地从顶位移向高配位位点,即电位依赖的位点偏好,这可归因于电位逐渐增强了Cu(100)向吸附CO的电荷反馈过程.其次,提出了含碳中间体之间吸引性的横向交互作用是低覆盖度下C-C偶联的关键前提,这将确保含碳中间体在低覆盖度下可以实现局部聚集,因此,结合电位依赖的位点偏好和吸附质之间不同的横向相互作用,识别了不同电位下的C-C偶联机制.在低电位下(-0.4至-0.6V_(RHE)),CO分子主导地吸附在表面桥位上,其可吸引另一个CO聚集在一起,进而形成C-C键。计算的CO_(b)-CO_(b)偶联能垒为0.62eV.形成的OCCO中间体可以在低电位下逐步被还原为C_(2)H_(4).而在中等电位下(-0.6至-0.8VRHE),四配位键合的CO将成为主导,但由于排斥性的横向交互作用,它倾向于与另一个CO分子游离分散,这阻碍了偶联过程,导致C_(2)H_(4)性能逐渐衰退并最终停止.在高电位下(-0.8至-1.0V_(

关 键 词：Electrochemical CO reduction reaction Lowco coverage Dynamic site-preference Potential-dependent C-C coupling Constant-potential density functional theory 

分 类 号：O643.36[理学—物理化学] O643.32[理学—化学]