解析单颗粒电化学分步电子转移步骤用于识别电催化剂本征活性  

Clarifying sequential electron‐transfer steps in single‐nanoparticle electrochemical process for identifying the intrinsic activity of electrocatalyst

作　　者：孙泽晖 来壮壮 赵影影 陈建富[2] 马巍 Zehui Sun;Zhuangzhuang Lai;Yingying Zhao;Jianfu Chen;Wei Ma(Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering,Feringa Nobel Prize Scientist Joint Research Center,Frontiers Science Center for Materiobiology and Dynamic Chemistry,School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China;State Key Laboratory for Green Chemistry Engineering and Industrial Catalysis,Centre for Computational Chemistry and Research Institute of Industrial Catalysis,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化学与分子工程学院,材料生物学和动态化学前沿科学中心,先进材料重点实验室和费林加诺贝尔奖科学家联合研究中心国际合作联合实验室,上海200237 [2]华东理工大学计算化学中心和工业催化研究所,绿色化学工程与工业催化国家重点实验室,上海200237

出　　处：《Chinese Journal of Catalysis》2024年第5期262-271,共10页催化学报（英文）

基　　金：重大研究计划培育项目(92061108);国家自然科学基金面上项目(22272052);中央高校基本科研业务费。

摘　　要：揭示电催化剂本征活性对于量化其构-效关系至关重要.传统的整体表征方法只能提供大量纳米颗粒(NP)的平均性能,并且通常难以排除添加剂的贡献.单颗粒碰撞电化学(SNCE)技术能够有效地在单NP水平上揭示电催化剂活性.尽管SNCE领域已取得了很大的研究进展,但目前人们对其反应中的电子转移过程认识尚不充分,难以提供NPs结构与活性之间的定量关系.本文以铂纳米颗粒(PtNPs)氧还原反应(ORR)作为SNCE过程的模型体系,通过构建功能化锥形碳微米电极(CNE)界面,有效地调控了ORR电催化过程,揭示了SNCE分步电子转移在调节单个PtNP表观ORR活性中的重要作用.分别采用化学刻蚀和元素功能化技术调控CNE界面的表面粗糙度和氮元素掺杂组成,构筑了光滑碳电极(s-CNE)、粗糙碳电极(r-CNE)、光滑氮掺杂碳电极(sN-CNE)和粗糙氮掺杂碳电极(rN-CNE)四种功能化电极界面.实验表明,单个PtNP在s-CNE、r-CNE、sN-CNE和rN-CNE这四种功能化CNE界面上产生的ORR电流强度依次增大(即s-CNE<r-CNE<sN-CNE<rN-CNE),且在rN-CNE表面达到了扩散控制的极限电流.这一发现证明了,通过对电极界面进行功能化处理可以显著提升PtNPs的ORR性能,这是由于单个PtNP的ORR总反应速率受决速步控制.密度泛函理论计算和表征结果表明,对电极界面进行表面粗糙化处理或氮元素掺杂可以分别调控SNCE电催化中的单步电子转移过程,即增强NP与电极间的电子传递速率或NP的异相动力学速率.为深入解析这一复杂过程,构建了一个多物理场理论模型.该模型将NP与电极间的电子转移、NP表面的异相电子转移以及溶液中的物质传递作为SNCE过程中的连续步骤.通过将理论模拟与高分辨电化学测量相结合,成功量化了SNCE分步电子转移步骤的相应参数,包括NP与电极间的接触电阻、NP的异相动力学常数以及NP与电极间的吸附概率,从而明确了提高电催化�Single-nanoparticle collision electrochemistry(SNCE)is an effective method for determining the intrinsic activity of electrocatalysts at the single-nanoparticle(NP)level.Despite fruitful advancements in the SNCE field,determining a quantitative relationship between the NP structure and its activity has remained difficult because of an unclear understanding of SNCE.In this study,we successfully uncovered the essential roles of the sequential electron-transfer steps in the SNCE system in regulating the apparent electrocatalytic activity of single NPs.By monitoring the oxygen reduction reaction of individual Pt NPs,significantly distinct apparent activities were observed at different electrodes owing to the rate-determining step-controlled electron transfer process.Furthermore,a new theoretical model is proposed for treating the electrochemical current,which involves NP-electrode electron transfer,heterogeneous electron transfer,and mass transfer in solution as sequential steps in the SNCE system.The combination of theoretical simulations and high-resolution electrochemical measurements allows for the corresponding parameters(contact resistance,heterogeneous kinetic constants,and adsorption possibility)of sequential electron-transfer steps to be quantified,resulting in the identification of a rate-determining step for improving the intrinsic activity of electrocatalysts.This work provides a clear picture for determining the intrinsic activity of single NPs in SNCE measurements and introduces a new conceptual route for the quantification of structure-activity relationships,which ultimately guide the rational design and optimization of electrocatalytic nanomaterials.

关 键 词：单颗粒 电催化剂 电子转移 决速步 本征活性 

分 类 号：TQ426[化学工程] X701[环境科学与工程—环境工程]