Reviewed by Lexie CornerNov 18 2024
Scientists from Tohoku University have made significant progress in improving the effectiveness of an electrochemical reaction that generates hydrogen peroxide, a key chemical used in industrial processes such as sewage treatment, bleaching, and disinfection. The research was published in the journal Advanced Materials.
Integration of magnetic nanoparticles with molecular catalysts: Schematic illustration showing the CoPc/CB-Mag catalyst with polymer-protected magnetic nanoparticles, enabling spin state manipulation of cobalt centers. Image Credit: ©Hao Li et al.
The oxygen reduction reaction (ORR) was enhanced through the development of a novel class of heterogeneous molecular catalysts incorporating an integrated magnetic field.
Traditional methods for producing hydrogen peroxide (H2O2) have several drawbacks. The concentrated product is difficult to transport safely, and the process consumes a lot of energy. To address these issues, the research team aimed to develop an environmentally friendly and more efficient electrochemical approach.
The research team created the novel catalyst by attaching cobalt phthalocyanine (CoPc) molecules to carbon black (CB) and combining them with polymer-protected magnetic (Mag) nanoparticles. This unique structure significantly improves catalytic performance by allowing effective manipulation of the spin states of the cobalt active sites.
The CoPc/CB-Mag catalyst greatly enhanced the efficiency of the reaction, producing an impressive 90 % H2O2, the researchers found. Notably, the catalyst uses up to seven orders of magnitude less magnetic material than other methods, making it 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. This spin transition dramatically improves the catalyst's intrinsic activities in both oxygen reduction and evolution reactions.
Di Zhang, Advanced Institute for Materials Research, Tohoku University
The researchers used complete density functional theory (DFT) simulations to understand the fundamental mechanism behind this novel catalyst. Further research is needed to fully comprehend how and why it functions.
We found that the high-spin Co site exhibits stronger binding with oxygen-containing intermediates, which is crucial for efficient catalysis. The magnetic field-induced spin polarization also facilitates electron transfer and spin transitions during the reaction steps, boosting the catalytic kinetics.
Hao Li, Associate Professor, Tohoku University
Li added, “The combination of experimental results and theoretical insights provides a comprehensive picture of how magnetic fields can enhance catalytic performance. This can serve as guidance when designing new catalysts in the future.”
The findings could contribute to global efforts to develop carbon-neutral energy technologies and sustainable industrial processes by guiding the design of catalytic active materials. The aim is to create more cost-effective and environmentally friendly methods for producing hydrogen peroxide and other valuable chemicals.
Journal Reference:
Yu, Z., et al. (2024) Spin Manipulation of Heterogeneous Molecular Electrocatalysts by an Integrated Magnetic Field for Efficient Oxygen Redox Reactions. Advanced Materials. doi.org/10.1002/adma.202408461.