New Insight into the Electronic Effect for Cu Porphyrin Catalysts in Electrocatalytic of CO2 into CH4,Small

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New Insight into the Electronic Effect for Cu Porphyrin Catalysts in Electrocatalytic of CO2 into CH4
Small ( IF 13.0 ) Pub Date : 2023-09-05 , DOI: 10.1002/smll.202304998
Hao Jiang ₁ , Peng Zhao ₁ , Haidong Shen ₁ , Shaowei Yang ₁ , Runze Gao ₁ , Ying Guo _{1,

2} , Yueling Cao ₁ , Qiuyu Zhang ₁ , Hepeng Zhang _{1,

2}

Affiliation

Perturbation of the copper (Cu) active site by electron manipulation is a crucial factor in determining the activity and selectivity of electrochemical carbon dioxide (CO₂) reduction reaction (e-CO₂RR) in Cu-based molecular catalysts. However, much ambiguity is present concerning their electronic structure–function relationships. Here, three molecular Cu-based porphyrin catalysts with different electron densities at the Cu active site, Cu tetrakis(4-methoxyphenyl)porphyrin (Cu─T(OMe)PP), Cu tetraphenylporphyrin (Cu─THPP), and Cu tetrakis(4-bromophenyl)porphyrin (Cu─TBrPP), are prepared. Although all three catalysts exhibit e-CO₂RR activity and the same reaction pathway, their performance is significantly affected by the electronic structure of the Cu site. Theoretical and experimental investigations verify that the conjugated effect of ─OCH₃ and ─Br groups lowers the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbitals (LUMO) gap of Cu─T(OMe)PP and Cu─TBrPP, promoting faster electron transfer between Cu and CO₂, thereby improving their e-CO₂RR activity. Moreover, the high inductive effect of ─Br group reduces the electron density of Cu active site of Cu─TBrPP, facilitating the hydrolysis of the bound H₂O and thus creating a preferable local microenvironment, further enhancing the catalytic performance. This work provides new insights into the relationships between the substituent group characteristics with e-CO₂RR performance and is highly instructive for the design of efficient Cu-based e-CO₂RR electrocatalysts.

中文翻译：

铜卟啉催化剂电催化 CO2 转化为 CH4 的电子效应的新见解

通过电子操纵对铜（Cu）活性位点的扰动是决定铜基分子催化剂中电化学二氧化碳（CO ₂ ）还原反应（e-CO ₂ RR）活性和选择性的关键因素。然而，它们的电子结构-功能关系还存在很多模糊性。这里，三种分子铜基卟啉催化剂在铜活性位点具有不同的电子密度：四(4-甲氧基苯基)卟啉铜(Cu─T(OMe)PP)、四苯基卟啉铜(Cu─THPP)和四(4)铜制备了-溴苯基）卟啉（Cu─TBrPP）。尽管所有三种催化剂都表现出e-CO ₂ RR活性和相同的反应途径，但它们的性能受到Cu位点的电子结构的显着影响。理论和实验研究证实，─OCH ₃和─Br基团的共轭效应降低了Cu─T(OMe)PP和Cu─TBrPP的最高占据分子轨道(HOMO)-最低未占据分子轨道(LUMO)间隙，促进了更快的反应Cu和CO ₂之间的电子转移，从而提高它们的e-CO ₂ RR活性。此外，─Br基团的高诱导效应降低了Cu─TBrPP的Cu活性位点的电子密度，有利于结合的H ₂ O的水解，从而创造了良好的局部微环境，进一步增强了催化性能。这项工作为取代基特征与e-CO ₂ RR性能之间的关系提供了新的见解，对于设计高效的Cu基e-CO ₂ RR电催化剂具有很强的指导意义。

更新日期：2023-09-05

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