Published papers

Carbon capture, utilization, and storage (CCUS) have been attracting much attention as an initiative to achieve carbon neutrality. In the capture and storage strategy, amines are widely used for highly efficient separation and capturing of CO2 since amines react with CO2 to form carbamates. In the utilization strategy, CO2 electroreduction is a promising method to convert CO2 into value-added compounds because reaction conditions are relatively mild and easily controlled. In this work, toward combining CO2 capture and storage technologies and CO2 electroreduction, we focused on amine modification of the electrode surface, in which boron-doped diamond (BDD) was chosen as a sustainable electrode material. CO2 electroreduction using the amine-modified BDD was performed, and an applied potential dependence of the product selectivity was examined. In situ attenuated total reflectance-infrared measurements showed that the peak intensity of the stretching vibration of the carbonyl group at around 1640 cm-1 decreased as applied potentials became more negative. The effect of amine modification of the BDD surface lies in the formation of a C-N bond during CO2 electroreduction, resulting in the enhancement of the selectivity of CO production up to 8 times compared to the unmodified BDD.

The manipulation of Fe3+ spin states from high spin (HS; s=5/2) in bulk crystals to mixed spin lattices (with s=5/2 and low spin (LS); s=1/2) is demonstrated in a two-dimensional ultrathin metal-organic layer catalyst by mechanical exfoliation. The resulting catalyst has enhanced activity and selectivity for CO2 photoreduction (CO2RR) over the hydrogen evolution reaction (HER).

Silicon carbide (SiC) has excellent properties such as chemical and physical stability, biocompatibility, and high thermal conductivity. However, electrical conductivity of SiC is not high enough for electrochemical applications, which has been a major challenge. Here, in order to improve the conductivity, we prepared boron-doped SiC (SiC:B) and evaluated the electrochemical properties. SiC and SiC:B were fabricated by a microwave plasma chemical vapor deposition method. Structural characterization revealed that the main phase of SiC:B is 3C–SiC where the concentration of doped boron could be controlled by tuning the growth conditions. Electrochemical properties were evaluated by cyclic voltammetry measurements, indicating that the reactivity and sensitivity of the SiC:B electrode was comparable of that of the glassy carbon electrode.

© 2017 Elsevier Ltd Controlled surface functionalization of electrode materials is an important technique in various fields such as analytical chemistry, molecular electronics, and molecular recognition in biological systems. In this work, we report the control decoration of boron-doped diamond (BDD) electrodes by electrochemically driven copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of alkyne and azide (e−CLICK) in which the catalyst is produced by electroreduction of copper(II) species. As the e−CLICK strategy enabled to tune the produced amount of the copper(I) catalyst electrochemically, the alkyne-terminated BDD electrodes were decorated with azide-terminated ferrocene in a controlled manner.