Dual atom catalysts for rapid electrochemical reduction of CO to ethylene

Strong CO adsorption and facile CO dimerization are the key challenges in electrochemical CO2 reduction towards multi-carbon (C2+) products. We recently showed that CoPc immobilized on a single-walled carbon nanotube can selectively reduce CO2 to methanol. This is enabled through molecular strain, which dramatically improves the CO adsorption energy to CoPc, which in turn facilitates methanol formation. We now examine the extended Phthalocyanine (PcEx) dual atom catalyst (DAC), which is intrinsically strained and contains two catalyst centers, making it a candidate for reducing CO to C2+ products. Using Quantum Mechanics (QM), we screened 20 elements embedded in the PcEx, seeking catalysts with weak hydrogen binding, strong CO binding, and facile CO dimerization. We identified Fe, Ru, Co, and Ir as the best performers and subsequently evaluated the entire CO to C2H4 mechanism (9 steps) using each of these elements as catalysts. In terms of limiting potential and overall exergonicity, we identified CoPcEx as the best catalyst, followed by IrPcEx. We then examined the full CO to C2H4 mechanism on the bimetallic IrCoPcEx catalyst using grand canonical QM to obtain the reaction energetics as a function of applied potential. We conclude that the bimetallic IrCoPcEx is most promising for efficiently converting CO to ethylene.

Automated summary

This study focuses on the key challenges of strong CO adsorption and facile CO dimerization in electrochemical CO2 reduction towards multi-carbon (C2+) products. By immobilizing CoPc on a single-walled carbon nanotube, selective reduction of CO2 to methanol is achieved through molecular strain. Fe, Ru, Co, and Ir are identified as the best catalysts among 20 elements embedded in PcEx, and CoPcEx is found to be the most promising catalyst for efficiently converting CO to ethylene. The bimetallic IrCoPcEx catalyst is also examined and shows potential for this conversion.