Molecular Cobalt-NHC Hydrogen Evolution Catalysts: Unique Mechanisms and Ultrafast Catalysis in Aqueous Media

 

Molecular Cobalt-NHC Hydrogen Evolution Catalysts: Unique Mechanisms and Ultrafast Catalysis in Aqueous Media

 

Date: 9^th July, 2025 (Wednesday)

Time: 5 - 6 pm (HKT)

 

Venue: Lecture Theatre P3, Chong Yuet Ming Physcis Building

 

Prof. Kosei Yamauchi

 

Institute of Advanced Study

Kyushu University

 

Prof. Kosei Yamauchi received his undergraduate education in the Department of Chemistry, Faculty of Science, Kyushu University, Japan. After spending the graduate course at the same university, he became an assistant professor at the same department in 2012, prior to earning Ph.D. (Science) in 2015. He was promoted to associate professor at the Institute for Advanced Study, Kyushu University in 2025. He has a special interest in the coordination chemistry for energy conversion. He was selected as the JST PRESTO “Future Materials” researcher in 2022. In this JST PRESTO project, he is pioneering molecular catalysis of cobalt-NHC complexes for hydrogen evolution from acidic, neutral and alkaline water.

 

Energy conversion based on hydrogen evolution reaction (HER)¹ and CO₂ reduction into various chemicals^2,3 are the key technologies to solve the global warming and shortage of fossil fuels. It is also important to couple these reduction reactions with water oxidation⁴ to convert solar energy into chemical energy. In this context, we have successfully demonstrated that a macrocyclic cobalt-NHC catalyst Co-NHC1 represents the first example of the 1st row transition metal complex promoting HER using MV⁺• (methylviologen cation radical) as a reductant. In addition, experimental and DFT results also reveal that a unique double CPET pathway is taken to evolve H₂ by Co-NHC1, which can be viewed as related to the so-called Volmer-Heyrovsky mechanism adopted by some metals.¹ Meanwhile, we have recently conducted the detailed analyses on the electrocatalysis of Co-NHC1 for hydrogen evolution from water. Importantly, the catalytic rate by Co-NHC1 has turned out to be extremely high even in neutral aqueous media.⁵ Our recent finding includes the development of the highly efficient molecular system in photochemical H₂ evolution from alkaline water.

 

[1] K. Yamauchi*, K. Kawano, K. Yatsuzuka, K. Kawamura, M. Kan, K. Sakai*, J. Am. Chem. Soc., 2025, 147, 5602-5614 (Supplementary Cover).

[2] D. Lee, K. Yamauchi*, K. Sakai*, J. Am. Chem. Soc., 2024, 146, 31597-31611.

[3] C. Liao, K. Yamauchi*, K. Sakai*, ACS Catal., 2024, 14, 11131-11137.

[4] Y. Aimoto, A. R. Parent*, K. Yamauchi*, K. Sakai*, J. Am. Chem. Soc., 2024, 146, 16866-16877.

[5] M. Kan, K. Yamauchi*, K. Sakai*, Submitted.