The Yabu Laboratory at Tohoku University has made a significant breakthrough in the field of carbon dioxide (CO2) reduction. Their research, published in the journal Small on September 30, 2025, introduces a novel electrocatalyst that enhances the efficiency of CO2 electroreduction. By utilizing cobalt tetraazaphthalocyanine (CoTAP), the team achieved a mass activity that is 3.77 times greater than that of the traditional cobalt phthalocyanine (CoPc).
The electrochemical reduction of CO2 is a crucial method for addressing the pressing global challenge of greenhouse gas emissions. This process not only converts CO2 into valuable materials like carbon monoxide (CO) but also aligns with renewable energy initiatives, making it a promising strategy to combat climate change. Currently, the most effective catalysts for this process are often made from expensive noble metals, which limit their widespread application due to high costs and varying selectivity.
To tackle these challenges, the Yabu Laboratory has previously explored innovative techniques for developing cost-effective catalysts. Their earlier work focused on direct crystallization methods for inexpensive M-Pcs and their application on carbon materials. These strategies were successful in achieving decent CO2-to-CO efficiency and durability, yet further enhancement was required to improve catalytic performance.
In their latest study, the research team applied their second strategy to CoTAP, which has gained attention for its potential in fuel cells and metal-air batteries. The modification of CoPc with pyridinic nitrogen rings enhances its electrostatic interaction with CO2 molecules, thereby improving adsorption at catalytic sites. The researchers crystallized both CoPc and CoTAP on the conductive carbon material Ketjen Black (KB) and subsequently tested their performance on gas diffusion electrodes.
The results were promising. CoTAP electrodes demonstrated a remarkable Faradaic efficiency exceeding 98% for the conversion of CO2 to CO. Additionally, they achieved high electrolysis rates at current densities over 1 A/cm2 and exhibited durability for 112 hours at 150 mA/cm2. The enhanced performance of CoTAP is attributed to its lower electrical resistance and improved conductivity compared to CoPc crystals.
Hiroshi Yabu, the lead researcher at WPI-AIMR, expressed his enthusiasm for the findings, stating, “Compared with previously reported M-Pc-based catalysts, CoTAP delivered outstanding results across all metrics, including maximum current density, turnover frequency, durability, mass activity, and Faradaic efficiency.” This advancement not only demonstrates a viable alternative to noble metals but also opens pathways for reducing the energy costs associated with CO2 utilization.
The implications of this research are significant. By providing a more efficient and cost-effective method for CO2 reduction, the findings could accelerate the development of next-generation carbon capture and utilization technologies. This breakthrough represents a critical step toward transforming waste CO2 into valuable resources, contributing to a cleaner and more sustainable future for society.
