Attenuating metal-substrate conjugation in atomically dispersed nickel catalysts for electroreduction of CO2 to CO

• Published in: Nature communications Vol. 13; no. 1; pp. 6082 - 10
• Main Authors: Wang, Qiyou, Liu, Kang, Hu, Kangman, Cai, Chao, Li, Huangjingwei, Li, Hongmei, Herran, Matias, Lu, Ying-Rui, Chan, Ting-Shan, Ma, Chao, Fu, Junwei, Zhang, Shiguo, Liang, Ying, Cortés, Emiliano, Liu, Min
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14-10-2022; Nature Publishing Group; Nature Portfolio
• Subjects: 140/146; 147/143; 639/301/299/886; 639/638/161/886; 639/638/675; 639/638/77/887; Attenuation; Carbon; Carbon dioxide; Carbon dioxide concentration; Carbon monoxide; Catalysts; Conjugation; Dispersion; Electrocatalysts; Electron density; Electrowinning; Heavy metals; Humanities and Social Sciences; Infrared reflection; Infrared spectroscopy; Metals; multidisciplinary; Nickel; Science; Science (multidisciplinary); Single atom catalysts; Substrates; Transition metals
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-33692-0

Atomically dispersed transition metals on carbon-based aromatic substrates are an emerging class of electrocatalysts for the electroreduction of CO
2
. However, electron delocalization of the metal site with the carbon support via d-π conjugation strongly hinders CO
2
activation at the active metal centers. Herein, we introduce a strategy to attenuate the d-π conjugation at single Ni atomic sites by functionalizing the support with cyano moieties. In situ attenuated total reflection infrared spectroscopy and theoretical calculations demonstrate that this strategy increases the electron density around the metal centers and facilitates CO
2
activation. As a result, for the electroreduction of CO
2
to CO in aqueous KHCO
3
electrolyte, the cyano-modified catalyst exhibits a turnover frequency of ~22,000 per hour at −1.178 V versus the reversible hydrogen electrode (RHE) and maintains a Faradaic efficiency (FE) above 90% even with a CO
2
concentration of only 30% in an H-type cell. In a flow cell under pure CO
2
at −0.93 V versus RHE the cyano-modified catalyst enables a current density of −300 mA/cm
2
with a FE above 90%.
Electroreduction of CO
2
on single atom catalysts is often hindered by electron delocalization of the metal sites. To improve CO
2
activation, here the authors functionalize the carbon support with cyano moieties, thereby attenuating metal-substrate conjugation and improving CO
2
to CO conversion.