Akichika Kumatani

Carbon-based metal-free catalysts for the hydrogen evolution reaction (HER) are essential for the development of a sustainable hydrogen society. Identification of the active sites in heterogeneous catalysis is key for the rational design of low-cost and efficient catalysts. Here, by fabricating holey graphene with chemically dopants, the atomic-level mechanism for accelerating HER by chemical dopants is unveiled, through elemental mapping with atomistic characterizations, scanning electrochemica

We have revealed practical charge injection at metal and organic semiconductor interface in organic field effect transistor configurations. We have developed a facile interface structure that consisted of double-layer electrodes in order to investigate the efficiency through contact metal dependence. The metal interlayer with few nanometers thickness between electrode and organic semiconductor drastically reduces the contact resistance at the interface. The improvement has clearly obtained when

A facile solution process for the fabrication of organic single crystal semiconductor devices which meets the demand for low-cost and large-area fabrication of high performance electronic devices is demonstrated. In this paper, we develop a bottom-up method which enables direct formation of organic semiconductor single crystals at selected locations with desired orientations. Here oriented growth of one-dimensional organic crystals is achieved by using self-assembly of organic molecules as the d

We have investigated the pulsed laser deposition (PLD) growth processes of spinel lithium titanates based on the preparation of Li4Ti5O12 and LiTi2O4 from a Li4Ti5O12 target. The Li/Ti atomic ratio of the species arriving at substrate during the deposition was only ∼0.5. The LiTi2O4 epitaxial thin films fabricated on MgAl2O4 (111) substrate exhibited high conductivity at room temperature (∼3.0 × 103 Ω−1 cm−1) and a superconducting transition temperature of ∼12 K. These values are the highest rep

Scanning electrochemical cell microscopy with a single barrel micro‐/nano‐pipette (SECCM) was applied to lithium iron phosphate (LiFePO 4 ) composite positive electrodes and an isolated LiFePO 4 secondary particle for lithium‐ion batteries. To analyze lithium‐ion (Li + ) charge or discharge process on the electrodes using local probe, a pipette filled with LiCl electrolyte solution and Ag/AgCl quasi‐reference counter electrode (QRCE) was used. Both the local electrochemical activities of LiFePO

We identified an interesting electrochemistry-driven “ in situ ” generation of S-vacancies of transition metal disulfides, which serves as an origin of promising electrochemical ammonia synthesis activity.

We have used a combination of dielectrophoretic assembly and Raman spectroscopy to characterize the disaggregation state of bundles of single-walled carbon nanotubes. The presence of semiconducting nanotubes following assembly indicates incomplete disaggregation of the nanotubes in the surfactant/solvent. We show that this combined technique is a more sensitive measure of the aggregation state of nanotubes than either optical absorption measurement or Raman spectroscopy alone.

We fabricated Li 4 Ti 5 O 12 (111) epitaxial thin films on α-Al 2 O 3 (0001) substrates by RF magnetron sputtering. Thin films of amorphous Li 4 Ti 5 O 12 were deposited at room temperature, and then the films were annealed at high temperatures for the formation of epitaxial thin films. Furthermore, we investigated the effect of niobium (Nb) incorporation into Li 4 Ti 5 O 12 . The Nb-incorporated Li 4 Ti 5 O 12 thin films showed an improvement in crystallinity with a narrower rocking curve full

The ability of two-dimensional, layered transition-metal dichalcogenides (TMDs) to promote hydrogen evolution reaction (HER) has attracted much attention for hydrogen-generation applications. Their electrocatalytic active sites originally come from unique electronic properties at the edges. Here, we use scanning electrochemical cell microscopy (SECCM) to visualize and quantify the electrochemical HER activities of tungsten disulfide (WS2) islands. We show that the HER correlated current distribu