Kazuyuki Iwase

The electrochemical oxygen reduction reaction (ORR) is an important cathode reaction of various types of fuel cells. The development of electrocatalysts composed only of abundant elements is a key goal because currently only platinum is a suitable catalyst for ORR. Herein, we synthesized copper-modified covalent triazine frameworks (CTF) hybridized with carbon nanoparticles (Cu-CTF/CPs) as efficient electrocatalysts for the ORR in neutral solutions. The ORR onset potential of the synthesized Cu-

High-entropy spinel oxides (HE-SOs) with the first five transition metal elements were synthesized using a simple one-pot supercritical hydrothermal fluid processing method. Solid-solution cubic spinel oxide nanoparticles (average diameter = 18.6 nm) were successfully synthesized. The overpotential for the electrochemical oxygen evolution reaction (OER) on HE-SOs was 330 mV (at 10 mA cm–2 in 1 M KOH), and the value of the Tafel slope was 36.7 mV dec–1, demonstrating that the HE-SO functioned as

The development of oxygen reduction reaction (ORR) electrocatalysts comprising abundant elements is highly desirable for achieving widespread use of fuel cells. Optimal ORR catalysts should have moderate binding strength (ΔEads) with O2-derived intermediates, where the metal species and its coordination numbers are the essential determining factors for ΔEads. However, in conventional non-noble-metal-based ORR catalysts, such as metal–nitrogen-doped carbons, the metal species and its coordination

Electrochemical CO₂ reduction (CO₂ RR) is a key technology to convert greenhouse gas CO₂ to value-added products, such as CO and formic acid (HCOOH). In the present study, two-dimensional Cu- and Al-based layered double hydroxides (Cu-Al/LDHs) were applied as CO₂ RR catalysts. The catalysts were synthesized using a simple co-precipitation method employing sodium carbonate solutions with different pH and synthesis temperatures. The elemental ratio of Cu

Abstract The electrochemical oxygen reduction reaction (ORR) is an important cathode reaction of various types of fuel cells. The development of electrocatalysts composed only of abundant elements is a key goal because currently only platinum is a suitable catalyst for ORR. Herein, we synthesized copper‐modified covalent triazine frameworks (CTF) hybridized with carbon nanoparticles (Cu‐CTF/CPs) as efficient electrocatalysts for the ORR in neutral solutions. The ORR onset potential of the synthe

The electrocatalytic N2 reduction reaction (NRR) is one of the most promising methods for the on-site and on-demand production of NH3. Single-metal-atom-doped covalent organic frameworks (COFs) are expected to function as efficient NRR electrocatalysts because a designed coordination environment of metal centers is available as a consequence of the wide range of possible designs of COFs. Herein, we used density functional theory (DFT) to systematically investigate the theoretical NRR activity of

Abstract This work confirms a trade‐off relationship between the high redox potential of Cu and the oxygen‐binding ability of Cu‐based oxygen reduction reaction (ORR) electrocatalysts. As the ORR is mediated by Cu(I) species, a positive shift of the Cu(II/I) potential is required to increase the ORR onset potential. However, the ready simultaneous autoreduction of Cu(II) to Cu(I) in Cu complexes, owing to high redox potentials, results in the formation of a closed tetrahedral configuration that

The electroreduction of carbon dioxide is considered a key reaction for the valorization of CO₂ emitted in industrial processes or even present in the environment. Cobalt-nitrogen co-doped carbon materials featuring atomically dispersed Co-N sites have been shown to display superior activities and selectivities for the reduction of carbon dioxide to CO, which, in combination with H₂ (i.e., as syngas), is regarded as an added-value CO₂-reduction product. Such cata

The electrochemical CO₂ reduction reaction (CO₂RR) activity of Ni₂MnIn and Ni₂MnSn Heusler alloys was investigated. Although pure In, Sn and Ni₂MnIn generated formate as the major product, Ni₂MnSn generated H₂ as the major product. The CO₂RR selectivity could be controlled by selecting the constituent elements of the intermetallic catalysts.

A copper-modified covalent triazine framework (Cu-CTF) catalyzed the selective electrochemical reduction of nitrobenzene to aniline in neutral aqueous solutions with a faradaic efficiency reaching up to 65% at −0.6 V versus Ag/AgCl. Electrochemical characterization indicated that the organic-framework part of Cu-CTF reduced nitrobenzene to phenylhydroxylamine, followed by the reduction of phenylhydroxylamine to aniline at single Cu sites. This is the first example of a cooperative electrocatalyt

The electrochemical oxygen evolution reaction (OER) is an important anode reaction for electrochemical water splitting to generate hydrogen using renewable energy sources. Perovskite oxides (PV) have attracted attention as highly active OER catalysts in alkaline solutions, even without the use of precious metal elements. Here, we achieve precise tuning of the valence state of transition metal cations in BaFe1–xCoxO3–d (x = 0, 0.1, 0.2) and enhancement of the OER activity by broad-range fluorine

Additive manufacturing and especially 3D printing offer many advantages for the on-demand fabrication of wearable and/or custom made electronic devices. To realize completely custom made electronic devices entirely by 3D printing, adaptation, and development of 3D printing technologies for energy conversion devices that can serve as power sources, is also necessary. In the present study, a 3D printing technique that employs functional inks for the fabrication of proton exchange membranes was dev

Abstract Electrochemical CO 2 reduction has attracted significant attention as a potential method to close the carbon cycle. In this study, we investigated the impact of the electrode fabrication and electrolysis conditions on the product selectivity of Ag electrocatalysts using a machine learning (ML) approach. Specifically, we explored the experimental conditions for obtaining the desired H 2 /CO mixture ratio with high CO efficiency. Notably, unlike previous ML‐based studies, we used experime

Green hydrogen production via electrochemical water splitting extensively demands the development of cost-effective and highly efficient electrocatalysts for the anodic oxygen evolution reaction (OER). Nanosized spinel nanoparticles (nanospinels) are potential candidates as electrocatalysts for the OER because of their very high specific surface areas. This work systematically investigated the influence of the A-site metals in the Mn-based nanospinels, i.e., LiMn₂O₄, MgMn<s

Ag-Sn bimetallic alloys were synthesized via mechanical alloying using a ball-milling process as electrocatalysts for the carbon dioxide (CO2) reduction reaction. Single-phase intermetallic compounds or solid solutions of bimetallic Ag-Sn alloy were successfully synthesized. The main reaction product for the CO2 reduction reaction was formate over the synthesized Ag-Sn alloy catalysts, and the catalyst with an intermetallic phase exhibited the highest activity toward formate generation, especial