May 30, 2025

Single-atom catalysts change spin state when boosted by a magnetic field

Researchers proposed a completely novel strategy to apply an external magnetic field to modulate spin states, and thereby improve electrocatalytic performance.

(Nanowerk News) The job of a catalyst is to ultimately speed up reactions, which could reduce an hour-long process into several minutes. It has recently been shown that using external magnetic fields to modulate spin states of single-atom catalysts (SACs) is highly effective - enhancing oxygen evolution reaction magnetocurrent by a staggering 2,880%.

With this in mind, researchers at Tohoku University proposed a completely novel strategy to apply an external magnetic field to modulate spin states, and thereby improve electrocatalytic performance. This study (Nano Letters, "Magnetic-Field-Induced Spin Transition in Single-Atom Catalysts for Nitrate Electrolysis to Ammonia") provides valuable insights regarding the development of efficient and sustainable electrochemical technologies for ammonia production and wastewater treatment.

(a) Data mining on the magnetic field-enhanced electrocatalysis, including (b) the number of closely related literature and improved performance for ORR, (c) CO2RR and NO2-RR, and (d) the water splitting reactions. All literature data and the corresponding references were extracted via a large-scale data mining from the experimental literature published during the past decade, which are also available in the public Digital Catalysis Platform (DigCat) database. (Image: Hao Li et al.) (click on image to enlarge)

In the field of electrocatalysis, traditional methods mainly focus on adjusting the chemical composition and structure of catalysts. The introduction of magnetic-induced spin state modulation provides a new dimension for catalyst design and performance improvement. It involves the regulation of the electronic spin state of the catalyst through an external magnetic field, which can precisely control the adsorption and desorption processes of reaction intermediates, thus effectively reducing the activation energy of the reaction and allowing it to proceed more quickly.

"More efficient production processes can reduce costs, which may translate into lower prices for products such as fertilizers and treated water at the consumer level," explains Hao Li of Tohoku University's Advanced Institute for Materials Research (WPI-AIMR).

The study used advanced characterization techniques to prove that the magnetic field causes the transition to a high spin state, which improves nitrate adsorption. The theoretical analysis also shows the specific mechanics of why the spin state transition improves the electrocatalytic ability. When exposed to an external magnetic field, the Ru-N-C electrocatalyst demonstrated a high NH3 yield rate (~38 mg L-1 h-1) and a Faradaic efficiency of ~95% for over 200 hours. This represents a significant improvement compared to the exact same catalyst, but without a boost from an external magnetic field.

Ultimately, this work enriches our theoretical understanding of electrocatalysis by exploring the relationship between magnetic fields, spin states, and catalytic performance. At the same time, the experimental results offer a reference for future research and the development of new catalysts, laying a solid foundation for the practical application of electrochemical technologies.

Source: Tohoku University (Note: Content may be edited for style and length)