Junji Nakamura

Understanding how chemical energy dissipates as heat in non-equilibrium redox systems is a fundamental problem in physical chemistry.

Understanding how chirality emerges from assemblies of achiral molecules is central to the study of symmetry breaking at surfaces. Here we show that achiral 1,10‐phenanthroline adsorbed on Au(111) generates chirality through a pairing‐driven hierarchical self‐assembly pathway. Upon adsorption, molecules selectively form hydrogen‐bonded pairs via weak but directional C─H···N interactions. Steric and electrostatic constraints restrict this interaction to two molecules, forcing a choice between two symmetry‐equivalent nitrogen sites and thereby producing left‐ or right‐handed molecular pairs that act as local chiral motifs. These motifs organize through attractive intermolecular interactions into homochiral one‐dimensional chains, which further assemble into two‐dimensional chiral domains governed by repulsive interchain interactions. Scanning tunneling microscopy directly visualizes mirror‐related left‐ and right‐handed domains. Density functional theory calculations confirm that the face‐to‐face paired configuration is energetically preferred and stabilized by adsorption on Au(111). This work reveals a distinct route to surface chirality in which chirality originates at the level of a hydrogen‐bonded molecular pair and is amplified into organized chiral architectures through weak intermolecular interactions.

Ethanol synthesis from CO ₂ and H ₂ is currently a hot topic of research in heterogeneous catalysis. However, the underlying mechanism has not yet been clearly elucidated. We propose that the synthesis involves several other reactions on the electrode surface, as evident by the formation of a mixed potential. In this study, we prepared solid catalysts, Ru/CoO _x and CuPd/C, as the nano‐anode and nano‐cathode components and carried out CO ₂ hydrogenation in the presence of small amounts of water to facilitate ion conduction. Ethanol was produced along with CO, CH ₄ , and methanol at reaction temperatures below 473 K in the presence of both the catalysts. The activation energy for ethanol formation with Ru/CoO _x was found to be 25 ± 5 kJ mol ⁻¹ , which was much lower than those for the formations of CO (44 ± 4 kJ mol ⁻¹ ), CH ₄ (77 ± 7 kJ mol ⁻¹ ), and methanol (81 ± 9 kJ mol ⁻¹ ). In addition, the production of CO was promoted by the encapsulated water. These results also suggest a mixed‐potential‐driven mechanism for the synthesis of ethanol.

Gold is an effective catalyst for low‐temperature CO oxidation, yet its mechanism remains debated. Among the various proposed mechanisms, increasing attention has been given to a possible electrochemical pathway in recent studies. Here, experimental evidence is reported that CO oxidation at room temperature in electrolytes proceeds via coupled electrochemical CO oxidation and oxygen reduction half‐reactions, i.e., the mixed‐potential‐driven mechanism. A model system is designed with deposited Au nanoparticles (NPs) and nitrogen‐doped reduced graphene oxide (NrGO) on carbon paper acting as spatially separated electrodes in a single electrolysis cell. After shorting the two electrodes, the reaction current and mixed potential of the overall CO oxidation are measured without any externally applied bias. Independent current–potential curves for each half‐reaction are also obtained under identical experimental conditions. The intersection points of these curves, representing the predicted mixed potential and net current, showed good agreement with the values measured in the short‐circuited system. These results provide clear evidence that CO oxidation in aqueous media proceeds via a mixed‐potential‐driven mechanism, analogous to corrosion. This finding provides strong support for the hypothesis that low‐temperature CO oxidation over‐supported Au catalysts in the presence of water vapor proceeds via a similar electrochemical pathway in gas‐phase heterogeneous catalysis.

Nitrogen‐doped carbon catalysts are attracting significant attention as alternative electrocatalysts to platinum owing to their high activity and durability in fuel cells’ oxygen reduction reaction (ORR), resource availability, and low catalyst cost. Pyridinic nitrogen forms the active site of the ORR and that the reduction of pyridinium ions is discovered and adsorption of molecular oxygen are coupled with a unique reaction mechanism. The deactivation of nitrogen‐doped carbon catalysts in acid electrolytes is attributed to the protonation of pyridinic nitrogen and the associated hydration is reported. This concept is demonstrated by the increased activity of nitrogen‐doped graphene catalysts, whose hydrophobicity is enhanced by the 3D structure. To further enhance the catalytic activity of nitrogen‐doped carbon catalysts, the electronic configuration of the active sites, particularly the degree of electron localization and spin, plays a crucial role. As an example, the introduction of active sites through five‐membered ring structures is presented, along with their characterization by X‐ray absorption spectroscopy.

The oxygen reduction reaction (ORR) is a crucial process in electrochemical energy technologies, featuring fuel cells and metal‐air batteries in the coming carbon‐neutral society. Carbon materials have garnered significant attention as economical, sustainable alternatives to precious metal catalysts. In particular, there have been increasing reports recently that pentagons introduced into graphitic carbons promote catalytic activity for ORR. In addition, interesting studies are reported on carbon materials’ synthesis, characterization, and spin polarization properties with pentagonal defects. This review comprehensively summarizes the formation mechanism, characterization, spin, oxygen (O ₂ ) adsorption, and ORR catalytic activity of carbon catalysts with pentagonal defects. By connecting the dots between theoretical insights and experimental results, this review elucidates the fundamental principles governing pentagon‐related activity and offers perspectives on future directions for designing efficient ORR catalysts based on carbon materials.

The interaction between electron spin and oxygen molecules in non‐platinum catalysts, particularly carbon catalysts, significantly influences the catalytic performance of the oxygen reduction reaction (ORR). A promising approach to developing high‐performance catalysts involves introducing five‐membered ring structures with spin into graphitic carbons. In this study, we present the successful synthesis of cage‐like cubic carbon catalysts enriched with pentagon structures using pentagon ring‐containing C ₆₀ and a NaCl template. The number of pentagons contained in the structure was increased by doping with nitrogen and annealing, and the number of electron spins also increased, thereby improving catalytic activity. The prepared catalyst exhibits remarkable activity in ORR under acidic electrolytes. Furthermore, we elucidate the correlation between the pentagon structure, the number of spin, and catalytic activity, demonstrating that enhanced activity is contingent upon the presence of spin. Density functional theory (DFT) calculations support the role of spin in improving activity. The concept of spin and the introduction of pentagon structures provide new design principles for carbon catalysts.

The interaction between electron spin and oxygen molecules in non‐platinum catalysts, particularly carbon catalysts, significantly influences the catalytic performance of the oxygen reduction reaction (ORR). A promising approach to developing high‐performance catalysts involves introducing five‐membered ring structures with spin into graphitic carbons. In this study, we present the successful synthesis of cage‐like cubic carbon catalysts enriched with pentagon structures using pentagon ring‐containing C ₆₀ and a NaCl template. The number of pentagons contained in the structure was increased by doping with nitrogen and annealing, and the number of electron spins also increased, thereby improving catalytic activity. The prepared catalyst exhibits remarkable activity in ORR under acidic electrolytes. Furthermore, we elucidate the correlation between the pentagon structure, the number of spin, and catalytic activity, demonstrating that enhanced activity is contingent upon the presence of spin. Density functional theory (DFT) calculations support the role of spin in improving activity. The concept of spin and the introduction of pentagon structures provide new design principles for carbon catalysts.

We have recently proposed a theoretical model for the mechanism of heat production in the mitochondrial respiratory chain, derived from the overpotential of electrochemical reactions in enzyme catalysis. A key feature of this overpotential-derived thermogenesis model is that the distribution of energy consumption between thermogenesis and adenosine triphosphate synthesis changes depending on the reaction rate. To verify that similar energy partitioning occurs in other metabolic reactions linked to the respiratory chain, we developed a system for the simultaneous measurement of thermogenesis and respiration rate in yeast cells. We correlated the amount of thermogenesis with the respiration rate, finding that most thermogenesis in yeast cells is derived from fermentation, which is connected to the respiration rate. By investigating the relationship between fermentative heat production and respiration rate, we discovered that the energy partitioning between heat production and substance synthesis exists and changes depending on the respiration rate. This strongly suggests the existence of electrochemical overpotential-derived thermogenesis in metabolic processes.