Guo Chen, Zhang Tian, Lu Xiaoqing, Wu Chi-Man Lawrence
Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, P. R. China.
School of Materials Science and Engineering, China University of Petroleum Qingdao, Shandong, P. R. China.
ChemSusChem. 2021 Jul 6;14(13):2731-2739. doi: 10.1002/cssc.202100785. Epub 2021 May 13.
Electrochemical CO reduction reaction (CO RR) is an effective strategy converting CO to value-added products. Au is regarded as an efficient catalyst for electrochemical reduction of CO to CO, and the introduction of Pd can tune CO RR properties due to its strong affinity to CO. Herein, Au-Pd bimetallic electrocatalysts with different metal ratio were firstly investigated on CO RR mechanism by using density functional theory. The Au monolayer over Pd substrate and single Pd atom on Au(111) were found to show better CO RR selectivity against hydrogen evolution reaction (HER). Based on this, various single-atom catalysts on Au(111) and core-shell models with top Au monolayer were designed to study their CO RR performance. The results indicated that Pt, Cu, and Rh substrates below Au monolayer could enhance the activity and selectivity for CO production compared to pure Au, in which the limiting potential reduced from -0.74 to -0.63, -0.69, and -0.71 V, respectively. The single Pd embedded on Au(111) could adjust the adsorption strength, which provided an effective site to receive and further reduce CO to CH OH and CH at a low limiting potential of -0.61 V, and also avoided catalyst poisoning due to the over-strengthened CO adsorption caused by high Pd proportion on the surface. In addition, the adsorption energy of COOH was observed as a better CO RR reactivity descriptor than the common CO adsorption when establishing scaling relationship, which could avoid the fitting error caused by intermediate physisorption of CO.
电化学一氧化碳还原反应（CO RR）是将CO转化为高附加值产品的有效策略。金被认为是将CO电化学还原为CO的高效催化剂，而钯的引入因其对CO的强亲和力可调节CO RR性能。在此，首次利用密度泛函理论研究了不同金属比例的金-钯双金属电催化剂的CO RR机理。发现钯基底上的金单层和金（111）上的单个钯原子对析氢反应（HER）表现出更好的CO RR选择性。基于此，设计了金（111）上的各种单原子催化剂和具有顶层金单层的核壳模型，以研究它们的CO RR性能。结果表明，与纯金相比，金单层以下的铂、铜和铑基底可提高CO生成的活性和选择性，其中极限电位分别从-0.74降至-0.63、-0.69和-0.71 V。嵌入金（111）上的单个钯可调节吸附强度，在-0.61 V的低极限电位下提供了一个有效位点来接收并进一步将CO还原为CH OH和CH，还避免了由于表面高钯比例导致的CO吸附过强而引起的催化剂中毒。此外，在建立标度关系时，观察到COOH的吸附能是比常见的CO吸附更好的CO RR反应性描述符，这可以避免由CO中间物理吸附引起的拟合误差。
