Novel magnetic field integration enhances green hydrogen peroxide production

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Researchers have achieved a breakthrough in improving the efficiency of an electrochemical reaction that produces hydrogen peroxide—a vital chemical for industrial applications including disinfection, bleaching, and treating sewage. This reaction, called the oxygen reduction reaction (ORR), was improved by developing a new class of heterogeneous molecular catalysts with an integrated magnetic field. The research is published in Advanced Materials.

The conventional methods of producing hydrogen peroxide (H₂O₂) have unfortunate downsides. The process is energy-intensive, and the concentrated end product is difficult to transport safely. To solve these issues, the research team looked to an electrochemical method that is not only more efficient but also environmentally friendly.

The research team designed a novel catalyst by anchoring cobalt phthalocyanine (CoPc) molecules on carbon black (CB), then integrating it with polymer-protected magnetic (Mag) nanoparticles. This unique structure enables effective spin state manipulation of the cobalt active sites, significantly enhancing catalytic performance.

The researchers discovered the CoPc/CB-Mag catalyst achieved a remarkable H₂O₂ production efficiency of 90%. Notably, the catalyst requires only minimal amounts of magnetic materials—up to seven orders of magnitude less than previous approaches—making it both safer and more practical for large-scale applications.

"Our integrated magnetic field approach can shift the cobalt center from low-spin to high-spin state without modifying its atomic structure," said Di Zhang of the Advanced Institute for Materials Research (WPI-AIMR), "This spin transition dramatically improves the catalyst's intrinsic activities in both oxygen reduction and evolution reactions."

To understand the fundamental mechanism behind this new catalyst, the team used a technique called comprehensive density functional theory (DFT) calculations. Understanding why and how it works is important for future studies. "We found that the high-spin Co site exhibits stronger binding with oxygen-containing intermediates, which is crucial for efficient catalysis," explained Associate Professor Hao Li, "The magnetic field-induced spin polarization also facilitates electron transfer and spin transitions during the reaction steps, boosting the catalytic kinetics."

"The combination of experimental results and theoretical insights provides a comprehensive picture of how magnetic fields can enhance catalytic performance," added Li, "This can serve as guidance when designing new catalysts in the future."

The findings could lead to the rational design of catalytic active materials, targeting more efficient and environmentally friendly pathways to produce hydrogen peroxide and other value-added chemicals, contributing to global efforts in sustainable industrial processes and carbon-neutral energy technologies.

More information: Zixun Yu et al, Spin Manipulation of Heterogeneous Molecular Electrocatalysts by an Integrated Magnetic Field for Efficient Oxygen Redox Reactions, Advanced Materials (2024). DOI: 10.1002/adma.202408461

Journal information: Advanced Materials

Provided by Tohoku University