The discovery of mesoporous carbon support with characteristic porosity and the art of mastering its use
by The Electrochemical Society, BioLogic, Hitachi High-Tech · Physics WorldJoin the audience for a live webinar at 3 p.m. BST/10 a.m. EDT on 15 July 2026 High durability and oxygen diffusivity of mesoporous carbon support of CNovel® MH-18 used for PEFCs
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In 2020, Toyota Motor Corporation launched the FC-EV of MIRAI-II adopting mesoporous carbon of nano-dendrite (MCND) support for the PtCo alloy catalyst NPs to suppress ionomer poisoning. Concurrently, we began using the CNovel® MH-18 mesoporous carbon (MPC) support mass-produced by TOYO TANSO, Osaka, Japan. The characteristics of the MPC support were entirely different from those of the conventional Ketjen Black EC-600JD (KB-600JD) porous carbon support.
The MPC support has a primary particle size of approximately 2 μm (KB-600JD: 40–50 nm) and consists of isolated particles lacking the chain-like structure seen in KB-600JD. Thanks to very unique porosity of the MPC support, that is, the coexistence of highly interconnected mesopores (2–6 nm) and macropores, allows oxygen molecules to access the Pt catalyst NPs from all directions within the MPC support, resulting in higher cell voltages compared to the Pt/KB-600JD catalyst at high current density regions.
The MPC support was ground to approximately 800 nm using a bead mill. Since the grinding generates new surfaces on the MPC support, the ground MPC support was heat treated in an Ar atmosphere at temperatures ranging from 1800°C to 2400°C to improve the durability of the MPC support. The durability of the Pt/MPC (800 nm) catalyst was evaluated using a triangular-wave potential cycle of 1.0–1.5 V vs RHE in MEAs. The Pt/MPC (800 nm) catalyst using the freshly milled MPC support exhibited higher durability than the Pt/KB-600JD catalyst. This is because although new surfaces were formed by bead milling, the purchased MPC (2 µm) was heat treated at 1800°C under an Ar atmosphere during TOYO TANSO’s final manufacturing process.
The durability of the Pt/MPC (800 nm) catalyst increased with rising the heat-treatment temperature, and the catalyst using MPC support (800 nm) heat-treated at 2400°C exhibited the highest durability under a triangular-wave potential cycle of 1.0–1.5 V vs RHE.
XRD and HR-TEM analyses revealed that the carbon (002) plane grew further upon the heat treatment. The N2 gas adsorption/desorption isotherms measured at 77 K for the MPC supports indicated that porosity of the MPC support decreased with increasing the heat-treatment temperature, and the surface area of the freshly milled MPC support, 1338 m2/g, decreased to 351 m2/g after the heat treatment at 2400°C. Considering the durability and the porosity retention of the MPC support (800 nm), a heat-treatment temperature in the range of 2000°C–2200°C is considered suitable.
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Hideo Daimon completed his MSc in chemistry at the Faculty of Science, Kwansei Gakuin University, in 1984, he joined the research and development department at Hitachi Maxell, Ltd. At Hitachi Maxell, he conducted research on magnetic materials prepared via chemical routes; friction and wear of thin-film magnetic recording media, protective coatings and lubricants for the thin-film media, and electrodeposition and electroless plating of Ni and Ni-P films.
In 2000, he began synthesizing PtFe, PtRu and Pt nanoparticles for use in fuel cells. Daimon moved to Doshisha University in 2010, where he has been researching Pt and Pt-based catalysts used in cathodes for PEFCs, including Au@Pt- and Pd@Pt core-shell structured catalysts, as well as PtCo alloy catalysts. Currently, he is engaged in research on mesoporous carbon supports to enhance the cell performance and durability of PEFCs applied to FCEVs.