过电位
化学
石墨
法拉第效率
电化学
可逆氢电极
电极
密度泛函理论
光化学
物理化学
计算化学
工作电极
作者
Mingwei Fang,Linli Xu,Hongyang Zhang,Ying Zhu,Wai‐Yeung Wong
摘要
The electrochemical reduction reaction of carbon dioxide (CO2RR) to the desired feedstocks with a high faradaic efficiency (FE) and high stability at a high current density is of great importance but challenging owing to its poor electrochemical stability and competition with the hydrogen evolution reaction (HER). Guided by theoretical calculations, herein, a series of novel metalloporphyrin-linked mercurated graphynes (Hg-MTPP) were designed as electrocatalysts for CO2RR, since the mercurated graphyne blocks induce a high HER overpotential. Notably, Hg-CoTPP was synthesized and produced a maximum CO FE of 95.6% at −0.76 V (vs reversible hydrogen electrode (RHE)) in an H-type cell, and a CO FE of 91.2% even at −1.26 V (vs RHE), due to a great suppression of HER. The Hg-CoTPP combined with N-doped graphene (Hg-CoTPP/NG) was able to achieve a high CO FE of nearly 100% at a current density of 1.2 A cm–2 and particularly a ground-breaking stability of over 360 h at around 420 mA cm–2 in a flow-type cell. Further experimental and computational results revealed that the mercurated graphyne of Hg-CoTPP brings a high HER overpotential and tunes the d-band electronic states of the metal center that make the d-band center closer to the Fermi level, thus enhancing the bonding of *COOH intermediates on Hg-CoTPP. The introduction of NG could shorten the Co–N coordination bonds, which enhances electron transfer to the metal center to lower the energy barrier for *COOH. Our results illustrated that Hg-MTPP could serve as a new class of two-dimensional (2D) materials and provide a design concept for developing efficient electrocatalysts for CO2RR in commercial applications.
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