A Mn-N<sub>3</sub> single-atom catalyst embedded in graphitic carbon nitride for efficient CO<sub>2</sub> electroreduction.

Feng, Jiaqi; Gao, Hongshuai; Zheng, Lirong; Chen, Zhipeng; Zeng, Shaojuan; Jiang, Chongyang; Dong, Haifeng; Liu, Licheng et al. · Nat Commun · 2020

basic_science · Level V

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Abstract

Developing effective catalysts based on earth abundant elements is critical for CO<sub>2</sub> electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current density of CO (j<sub>CO</sub>) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N<sub>3</sub> site embedded in graphitic carbon nitride. The prepared catalyst exhibits a 98.8% CO FE with a j<sub>CO</sub> of 14.0 mA cm<sup>-2</sup> at a low overpotential of 0.44 V in aqueous electrolyte, outperforming all reported Mn SACs. Moreover, a higher j<sub>CO</sub> of 29.7 mA cm<sup>-2</sup> is obtained in an ionic liquid electrolyte at 0.62 V overpotential. In situ X-ray absorption spectra and density functional theory calculations demonstrate that the remarkable performance of the catalyst is attributed to the Mn-N<sub>3</sub> site, which facilitates the formation of the key intermediate COOH<sup>*</sup> through a lowered free energy barrier.