Scientists created a fast, affordable way to convert CO2 into synthetic fuel precursors using spray-coated catalysts and direct crystallization techniques.
What if we could turn harmful pollution into a valuable energy source? As the world moves toward carbon neutrality, developing new technologies that reduce emissions is essential.
Researchers from Tohoku University, Hokkaido University, and AZUL Energy, Inc. have created an efficient method for converting carbon dioxide (CO2) into carbon monoxide (CO), an important building block for synthetic fuels. Their process set a new benchmark by reducing the conversion time from 24 hours to just 15 minutes.
“CO2-to-CO conversion is currently a hot topic to address climate change, but the conventional techniques had major pitfalls that we wanted to address,” said Liu Tengyi of the WPI-AIMR at Tohoku University. “The materials were expensive, unstable, had limited selectivity, and took a long time to prepare. It just wouldn’t be feasible to use them in an actual industrial setting.”
Cost-effective catalyst design using phthalocyanines
To meet industrial needs, the researchers explored different types of phthalocyanines (Pc)—including metal-free (H2Pc), iron (FePc), cobalt (CoPc), nickel (NiPc), and copper (CuPc)—as potential catalysts. They applied these compounds to gas diffusion electrodes using a simple spray technique, which formed crystalline layers directly on the electrode surface. Among them, cobalt phthalocyanine (CoPc), a low-cost pigment and metal complex, demonstrated the highest efficiency in converting CO2 into CO.
This graffiti-like method of simply spraying the catalyst on a surface reduces the typical processing time down to a mere 15 minutes. Conventional methods required a tedious process of mixing conductive carbon and binders, drying, and heat treatment over 24 hours. Furthermore, under a current density of 150 mA/cm², the new system maintained stable performance for 144 hours.
Using the DigCat Database (the largest experimental electrocatalysis database to date), the researchers confirmed that their catalyst surpassed all previously reported Pc-based catalysts.
Meeting industrial benchmarks for co2-to-co conversion
“Not only is this the best Pc-based catalyst for producing CO to date, but it successfully exceeds the industrial standard thresholds for its reaction rate and stability,” remarks Liu. “It’s the first ever to make the cut.”
To investigate the reasons behind this high performance, the team conducted structural analysis using synchrotron radiation at the NanoTerasu facility, along with theoretical calculations. The results suggested that the crystallization led to densely packed molecules, which facilitated efficient electron transfer to the surface. These findings highlight that direct crystallization is an effective strategy for fabricating metal complex-based catalyst electrodes for CO₂ electroreduction.
The gas diffusion electrode fabrication method developed in this study, along with the CO2 electrolysis technology, offers a promising pathway for synthesizing carbon monoxide (CO), an important intermediate for synthetic fuels, from CO2 with high efficiency using low-cost pigment-based catalysts.
This approach addresses one of the key bottlenecks in synthetic fuel production by improving energy efficiency and reducing costs associated with CO2 utilization. As such, it holds great potential as a next-generation technology for Carbon Dioxide Capture and Utilization (CCU).
Reference: “Surface Charge Transfer Enhanced Cobalt-Phthalocyanine Crystals for Efficient CO2-to-CO Electroreduction with Large Current Density Exceeding 1000 mA cm−2” by Tengyi Liu, Di Zhang, Yutaro Hirai, Koju Ito, Kosuke Ishibashi, Naoto Todoroki, Yasutaka Matsuo, Junya Yoshida, Shimpei Ono, Hao Li and Hiroshi Yabu, 4 April 2025, Advanced Science.
DOI: 10.1002/advs.202501459
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