Yuta Nabae

The hybrid direct carbon fuel cell (HDCFC) with solid oxide and molten carbonate binary electrolyte merges solid oxide fuel cell (SOFC) and molten carbonate fuel cell technologies to achieve direct conversion of solid carbon to electric power. The purpose of this study is to investigate in detail the electrochemistry of the oxidation of solid carbon in the carbon/carbonate slurry in the HDCFC. A planar test cell has been fabricated employing conventional SOFC materials and a eutectic carbonate m

Ni-impregnated carbon black (Ni/XC-72R) was tested as a fuel for a hybrid direct carbon fuel cell (HDCFC) with a hybrid electrolyte of yttria-stabilized zirconia and molten carbonate . The open-circuit voltage (OCV) of the HDCFC with Ni/XC-72R was quite high, about 1.5 V at . The maximum power density was improved by factors of 7.6 and 3.1, respectively, at 550 and by adding 50 wt % of Ni catalyst. The effect of the Ni catalyst on the carbon/carbonate slurry was investigated by temperature-progr

Aerobic Baeyer–Villiger oxidation of ketones to corresponding esters was performed using metal-free carbon as a solid catalyst and benzaldehyde as the sacrificing agent. Several carbon materials were tested for the oxidation of cyclohexanone to ε-caprolactone, and it was found that Ketjen Black showed the highest catalytic activity, over 90% of ε-caprolactone yield at 50 °C. A catalyst recycling test suggests that the catalyst has high durability under the reaction condition of oxygen atmosphere

Nitrogen-doped carbon catalysts for the electrochemical oxygen reduction reaction (ORR) have great potential to substitute precious metal alloy catalysts for the electrochemical synthesis of H2O2 based on a fuel cell setup. Consequently, obtaining a kinetic understanding of nitrogen-doped carbon catalysts in acidic media is essential. In this study, the mathematically modified Damjanovic model and Nabae model were applied to calculate the kinetic constants for an N/C catalyst prepared from polyi

A high performance Pt-free cathode catalyst for polymer electrolyte fuel cells has been synthesized by the multi-step pyrolysis of polyimide fine particles with a diameter of about 100 nm.

The development of a non-precious metal (NPM) fuel cell catalyst is extremely important to achieve globalization of polymer electrolyte fuel cells due to the cost and scarcity of platinum. Here, we report on a NPM cathode catalyst prepared by the pyrolysis of spherical polyimide nanoparticles that contain small amounts of Fe additive. 60 nm diameter Fe-containing polyimide nanoparticles were successfully synthesized by the precipitation polymerization of pyromellitic acid dianhydride and 1,3,5-t

Electrocatalysis of a Pd–Ni/composite anode (small amounts of Pd–Ni catalyst on a lanthanum chromite-based porous composite anode) for direct oxidation of dry methane in solid oxide fuel cells (SOFCs) was studied at . Synergy of Pd and Ni catalysts was observed for the direct oxidation of dry methane. Maximum power densities with the Pd–Ni/composite anode were 150 and at 1073 and , respectively. Carbon deposition on the Pd–Ni/composite anode was quite low under both open- and closed-circuit cond

Pt-free cathode catalysts for polymer electrolyte membrane fuel cells have been prepared by multi-step pyrolysis of FePc and PhRs, in the best of which show extensively high initial cell performance and good durability compared to other present precious-metal-free cathode catalysts to date.

A Pt-free cathode catalyst for polymer electrolyte membrane fuel cells has been developed by multi-step pyrolysis of Fe phthalocyanine and phenolic resin and shows a quite promising fuel cell performance.

Sulfonic acid functionalized hyperbranched poly(ether sulfone) (SHBPES) was studied as a novel type of solid acid catalyst.

Understanding the mechanism of the oxygen reduction reaction over nonprecious metal catalysts is important for green and sustainable electrochemical energy conversion. This article presents our recent progress in kinetic studies using rotating ring-disk electrodes. We have established a mathematically and experimentally modified rotating ring-disk electrode approach to calculate the corresponding kinetic rate constants of the 4-e reduction of O2 to H2O (k1), the 2-e reduction of O2 to H2O2 (k2),

Nonplatinum metal (NPM) catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) have been developed; however, NPM catalysts still need to be improved in terms of both their catalytic activity and durability. To overcome these problems, an Fe active site contained within a more compact ligand than conventional, porphyrinic, 16-membered ring ligands, or more specifically, a hexaaza macrocyclic ligand with a 14-membered ring (14MR), was developed. In this s

For the broad application of polymer electrolyte fuel cells (PEFCs), the development of nonprecious-metal (NPM) catalysts for oxygen reduction is extremely important. To date, many NPM catalysts have been synthesized by pyrolyzing Fe-, N-, and C-containing precursors; however, they suffer from low density and uncertain chemical structure of their active sites. This study reports a novel 14-membered macrocyclic Fe complex, which was inspired by FeN4 centers in pyrolyzed catalysts, unlike typical