Development of new oxygen reduction catalyst to replace platinum by adopting a laser etching method

[Figure 1] A schematic diagram of the process of making a LaMnO3 + d catalyst powder crystallized by heat treatment combined with graphitized carbon after LaMnO3 + d material is synthesized by laser etching in solution

□ Professor Ji Young Jo's research team at the Gwangju Institute of Science and Technology (GIST) has developed a new catalytic material that can be used in batteries and fuel cells by using a laser-pulverizing method on the material that is contained in a solution.

  ∘ The oxygen reduction reaction catalyst developed by Professor Ji Young Jo (School of Materials Science and Engineering) is expected to reduce the cost of battery and fuel cell development significantly by replacing expensive platinum (Pt), which has been widely used in the past, and will contribute to the commercialization of research.

□ Platinum, which is currently the most commonly used catalyst, has high oxygen reduction activity *, low operating voltage and stability; however, it is a rare element that is expensive and has limitations in commercialization research and technical industrialization.

  * Oxygen Reduction Activity: How efficiently oxygen is reduced in the catalytic reaction is expressed as the mass of the substance or the current density per electrode area

  ∘ In particular, the existing chemical synthesis method for making catalytic platinum powder adds surfactants, reducing agents, and oxidizing agents. During this process, impurities and contaminants may be generated, and the synthesis process takes a long time.

Figure 2

[Figure 2] Characterization of oxygen reduction reaction of LaMnO3 + d catalyst (a, b) and electron micrograph (c, d) (a) Polarization curve of oxygen reduction reaction. LaMnO3 + d catalysts synthesized by laser etching in solution and annealing showed higher onset potential than bulk materials and reacted faster and showed a very high current density in the vicinity of operating voltage (0.7 V ~ 0.8 V). This shows very similar properties to the commercially available Pt / C 20 wt% catalyst. (B) Activity and inactivity per mass at operating voltage (0.8 V). The synthesized LaMnO3 + d catalyst shows about 20 times greater activity per mass and about 2 times greater inactivity than bulk materials. (C) and (D), respectively, of the synthesized LaMnO3 + d catalyst powder. It is possible to confirm the crystallized state to a size of about 24 nm.

The researchers used nanometer-scale lanthanum manganate catalysts with a perovskite structure by using a laser-assisted laser-assisted grinding of lanthanum manganate (LaMnO3 + d).

* Perovskite: The structural name of a substance made after the name of the Russian mineralogist L. A. Perovski. The general formula is ABX3, consisting of two A, B cations and one X anion. It is a structure that is attracting attention as an oxygen reduction catalyst.

The team obtained LaMnO3+ d powder by laser etching and then crystallized LaMnO3 + d catalyst powder by heat treatment combined with graphitized carbon. As a result of this catalyst, it was confirmed that the activity per mass at operating voltage (0.8 V) was about 20 times higher than that of commercially available platinum catalysts, and the inactivity was about 2 times higher than that of commercially available platinum catalysts.

Professor Ji Young Jo said, "This research has developed a technology that can produce high-purity oxide catalysts that can be used instead of expensive platinum, which is currently used in most batteries and fuel cells."

Professor Cho, JY

(From the left) Professor Ji Young Jo, Ph.D. student Wan Sik Kim, Dr. Gopinathan Anoop

This research was led by Professor Ji Young Jo (correspondent author), Ph.D. student Wan Sik Kim, Dr. Gopinathan Anoop (first co-author and doctoral researcher) and was supported by the National Research Foundation. It was published online on November 19, 2016, in the Journal of Catalysis.