Reaching the Fundamental Limitation in CO <sub>2</sub> Reduction to CO with Single Atom Catalysts
Saurav Ch. Sarma, Jesús Barrio, Alexander Bagger, Angus Pedersen, Mengjun Gong, Hui Luo, Mengnan Wang, Silvia Favero, Zhao Chang-xin, Qiang Zhang, Anthony Kucernak, Maria‐Magdalena Titirici, Ifan E. L. Stephens
Abstract
Abstract The electrochemical CO 2 reduction reaction (CO 2 RR) to value‐added chemicals with renewable electricity is a promising method to decarbonize parts of the chemical industry. Recently, single metal atoms in nitrogen‐doped carbon (MNC) have emerged as potential electrocatalysts for CO 2 RR to CO with high activity and faradaic efficiency, although the reaction limitation for CO 2 RR to CO is unclear. To understand the comparison of intrinsic activity of different MNCs, two catalysts are synthesized through a decoupled two‐step synthesis approach of high temperature pyrolysis and low temperature metalation (Fe or Ni). The highly meso‐porous structure results in the highest reported electrochemical active site utilization based on in situ nitrite stripping; up to 59±6% for NiNC. Ex situ X‐ray absorption spectroscopy (XAS) confirms the penta‐coordinated nature of the active sites. The catalysts are amongst the most active in the literature for CO 2 reduction to CO. The density functional theory calculations (DFT) show that their binding to the reaction intermediates approximates to that of Au surfaces. However, it is found that the turnover frequencies (TOFs) of the most active catalysts for CO evolution converge, suggesting a fundamental ceiling to the catalytic rates.