Using theory and data to create new single atom catalysts for cleaner chlorine production

Chlorine is an essential industrial chemical used in products ranging from disinfectants to plastics. Yet producing chlorine requires the chlorine evolution reaction (CER), a process that consumes a significant amount of electricity worldwide. Current industrial electrodes rely on noble metals such as ruthenium and iridium, materials that are both costly and limited.

A research team has now applied a data-driven and theory-guided approach to identify new catalyst candidates that do not require these scarce metals. Their work draws on a large collection of previously reported CER experiments and applies a "volcano" modeling analysis, which maps how small changes in atomic binding energies influence catalytic performance.

By combining these two approaches, the team designed a series of non-precious single-atom catalysts (SACs) for CER. The most promising of these, a nickel-based material called NiN₃O-O, was then synthesized and tested in the laboratory.

Under acidic conditions, the material enabled chlorine production at a low overpotential of 75 millivolts at 10 milliamperes per square centimeter, with 95.8% selectivity for chlorine gas. These values indicate efficient reaction progress with minimal energy loss, comparable to commercial electrodes that contain large amounts of noble metals.

Further analysis showed that the key to this performance lies in an oxygen atom positioned at the "on-top" site of the catalyst. This atom provides a favorable location for chloride ions to attach, allowing the reaction to proceed while limiting competing side reactions. The researchers liken the process to a well-designed parking space that naturally guides the right car into place while keeping others out.

"This study shows how combining big-data analysis with theoretical modeling can lead to practical catalyst design," said Hao Li, Distinguished Professor at Tohoku University's Advanced Institute for Materials Research (WPI-AIMR). "We hope our findings lead to methods that reduce both the material cost and energy usage in the industrial manufacturing of chlorine."

Li cautions, however, that to do this they will need to improve the durability of these catalysts under industrial conditions. "Ensuring stability at high current densities and over long operation times remains essential for potential commercial deployment."

Looking ahead, the researchers plan to integrate the catalyst into more advanced cell architectures and to study its behavior under real brine electrolysis conditions. These efforts aim to connect fundamental scientific insights with technologies suitable for large-scale chlorine production.

About the World Premier International Research Center Initiative (WPI)

The WPI program was launched in 2007 by Japan's Ministry of Education, Culture, Sports, Science and Technology (MEXT) to foster globally visible research centers boasting the highest standards and outstanding research environments. Numbering more than a dozen and operating at institutions throughout the country, these centers are given a high degree of autonomy, allowing them to engage in innovative modes of management and research. The program is administered by the Japan Society for the Promotion of Science (JSPS).

See the latest research news from the centers at the WPI News Portal: www.eurekalert.org/newsportal/WPI

Main WPI program site:  www.jsps.go.jp/english/e-toplevel

Advanced Institute for Materials Research (AIMR)

Tohoku University

Establishing a World-Leading Research Center for Materials Science

AIMR aims to contribute to society through its actions as a world-leading research center for materials science and push the boundaries of research frontiers. To this end, the institute gathers excellent researchers in the fields of physics, chemistry, materials science, engineering, and mathematics and provides a world-class research environment.