Layered Cobalt Catalyst Reimagines Pigment as a Pathway for Carbon Dioxide Recycling

Comparison of the structure and performance of the multilayer CoPc/KB core-shell hybrid in this work with previous single-layer molecular Pc-based catalysts for CO2-to-CO electroreduction.
Image Credit: ©Hiroshi Yabu et. al.

Researchers at the Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, have introduced a new approach for electrochemical carbon dioxide (CO₂) reduction. By designing multilayer cobalt phthalocyanine (CoPc)/carbon core-shell structures, the team has demonstrated a catalyst architecture that makes CO₂ conversion into carbon monoxide (CO) both stable and efficient.

The study combined large-scale data analysis and artificial intelligence (AI) to screen 220 molecular candidates. Cobalt phthalocyanine - widely known as a blue pigment - emerged as the most effective option for selective CO production. This discovery became the basis for constructing electrodes optimized for CO₂ utilization.

"We wanted to move beyond conventional thinking that isolated molecules perform best," said Hiroshi Yabu, a professor at the (WPI-AIMR) who led the research. "Instead, our results show that stacking these molecules in ordered layers produces a much stronger catalytic effect."

Cross-sectional schematic of the core-shell structure illustrating multilayer CoPc crystals on KB (left) and the corresponding high-resolution TEM image (right).
Image Credit: ©Hiroshi Yabu et. al.

The team created a hybrid design in which CoPc forms crystalline layers around conductive carbon particles. This multilayer core-shell catalyst showed high current density and maintained CO selectivity above 90% for extended operation, even under demanding electrochemical conditions.

A central insight from the study is that the enhanced performance originates from the multilayered arrangement rather than individual molecules. Experiments revealed that ordered stacking promotes charge transfer at the catalyst surface, while theoretical calculations confirmed that this electronic effect significantly increases catalytic activity.

"This project shows how combining data-driven material selection with nanoscale design can reveal new directions for CO₂ recycling," added Yabu. "The ability to predict and test structures systematically will help us move faster toward practical applications."

Comparison of key metrics from this work (red) versus those of 220 M-N-C materials from literature (blue).
Image Credit: ©Hiroshi Yabu et. al.

The findings suggest that multilayer molecular architectures may offer a pathway to more effective catalysts, not only for CO₂-to-CO conversion but also for other reactions central to clean energy production. The researchers now plan to test the system under industrial conditions and explore whether similar designs can enhance hydrogen or ammonia production.

By demonstrating how a familiar material--once mainly used as a pigment--can be reimagined for sustainable technologies, the work underscores the role of creative catalyst design in advancing carbon recycling. The study marks a step toward practical systems that can help reduce CO₂ emissions while producing fuels and useful chemicals.

Published in journal: Applied Catalysts B: Environment and Energy

Title: Breaking the single-molecule paradigm: Multilayer cobalt phthalocyanine/carbon core-shell structure as the superior active unit for CO2-to-CO electroreduction

Authors: Tengyi Liu,  Di Zhang,  Yue Chu,  Keitaro Ohashi,  Yutaro Hirai,  Koju Ito,  Kosuke Ishibashi,  Yasutaka Matsuo,  Junya Yoshida,  Shimpei Ono,  Kazuhide Kamiya,  Hao Li,  and Hiroshi Yabu

Source/Credit: Tohoku University

Reference Number: ms092625_01

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