化学
催化作用
选择性
吸附
纳米颗粒
法拉第效率
密度泛函理论
吉布斯自由能
可逆氢电极
氢
无机化学
化学工程
电化学
电极
纳米技术
物理化学
计算化学
热力学
有机化学
物理
材料科学
参比电极
工程类
作者
Dunfeng Gao,Hu Zhou,Jing Wang,Shu Miao,Fan Yang,Qianqian Wang,Jianguo Wang,Xinhe Bao
摘要
Size effect has been regularly utilized to tune the catalytic activity and selectivity of metal nanoparticles (NPs). Yet, there is a lack of understanding of the size effect in the electrocatalytic reduction of CO2, an important reaction that couples with intermittent renewable energy storage and carbon cycle utilization. We report here a prominent size-dependent activity/selectivity in the electrocatalytic reduction of CO2 over differently sized Pd NPs, ranging from 2.4 to 10.3 nm. The Faradaic efficiency for CO production varies from 5.8% at −0.89 V (vs reversible hydrogen electrode) over 10.3 nm NPs to 91.2% over 3.7 nm NPs, along with an 18.4-fold increase in current density. Based on the Gibbs free energy diagrams from density functional theory calculations, the adsorption of CO2 and the formation of key reaction intermediate COOH* are much easier on edge and corner sites than on terrace sites of Pd NPs. In contrast, the formation of H* for competitive hydrogen evolution reaction is similar on all three sites. A volcano-like curve of the turnover frequency for CO production within the size range suggests that CO2 adsorption, COOH* formation, and CO* removal during CO2 reduction can be tuned by varying the size of Pd NPs due to the changing ratio of corner, edge, and terrace sites.
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