ELECTROPHORETIC DEPOSITION OF METAL-PHTHALOCYANINE AS A HIGH- PERFORMANCE ELECTROCATALYST

Metal-phthalocyanines (MPc) has high chemical stability and high catalytic activities in electrochemical reactions such as oxygen reduction reaction (ORR), CO2 reduction, and so on. It has becoming known that the catalytic activity of MPc should depend on the crystal structures, i.e., alfa-type MPc gives higher activity than other phases. In this study, the alfa-structure controlled MPcs could successfully be prepared by an electrophoretic deposition (EPD) method on gas diffusion type carbon electrode (GDE) as an electrocatalyst. Double layered MPcs electrocatalyst prepared by EPD also gave high performance for ORR. MPc (M: Li, Mg, Mn, Fe, Co, Ni, Cu, Zn, Ag, Sn, Pb) was dissolved in dichloromethane solution with trifluoroacetic acid was used for EPD method at room temperature. GDE and Pt counter electrode were used EPD (DC: +40 - +100V, 1-10min). Crystal structures of the MPcs were investigated by XRD, UV-vis, SEM, FT-IR, etc. ORR properties were evaluated in a half-cell in 1M H2SO4 at 70°C with a potentiostat using reversible hydrogen electrode (RHE) and Pt plate as reference and counter electrodes, respectively. Most of the alfa-phase MPcs could be prepared by the EPD on GDEs using dichloromethane solution containing trifluoroacetic acid. However, MPcs (M=Li, Mg) couldn’t prepared by the same condition. Alfa-phase MPc doped GDE showed higher ORR activity than that of GDE loaded with beta-MPc. In the cathodic performance at 0.4 V vs. RHE (I0.4) and open circuit potential (Eocp) at 70ºC of gas-diffusion electrodes loaded with various alfa-MPc catalysts deposited by EPD method. The GDEs loaded with alfa-MPcs showed various open circuit potentials, depending on the central metal (M) of alfa-MPc. GDE loaded with alfa-FePc showed the highest open circuit potential among the alfa-MPcs. This indicates that alfa-FePc could produce effect on density of adsorbed oxygen in the catalytic layer in the GDE. Moreover alfa-FePc based electrode showed high activity even at lower overpotential range, in spite of its low activity at higher overpotential range. The change in the Tafel slops was observed which indicates the change in the mechanism of ORR. Tafel slope of -43mV/decade at lower overpotential range shows the oxygen reduction reaction route with the formation of peroxo species in which the hydrogenation desorption reaction is rapid. While, the higher overpotential the Tafel slope of -222mV/decade might show the route which the peroxo species are not formed, like the H2O2 formation route. On the other hand, the Tafel slope of the GDE loaded with alfa-CoPc was not changed in the wide overpotential range. Also, the alfa-CoPc could keep the catalytic activity for several cycles of measurements of cathodic polarization curves, while that of alfa-FePc changed in the cycles. The decrease in ORR cycle for alfa-FePc seems to be come from the large strength of oxygen adsorption of alfa-FePc. On the other hand, CoPc/FePc double layered electrocatalyst prepared by the EPD gave more higher performance for ORR and stability. Acknowledgment: This work was partially supported by the Grant from JST ACT-C and JSPS KAKENHI Grant Number 25410240

Measurement of effective wetting area at hydrophobic solid–liquid interface

Hypotheses: The effective wetting area, a parameter somewhat different from the apparent contact area at solid–liquid interfaces, plays a significant role in surface wettability. However, determination of the effective wetting area for hydrophobic surfaces remains an open question. Therefore, in the present study, we developed an electrochemical impedance method to evaluate the effective wetting area at a hydrophobic solid–liquid interface. Experiments: Patterned Si surfaces were prepared using the anisotropic wet etching method, and the water contact angle and electrochemical impedance were measured experimentally. The effective wetting area at the solid–liquid interface was examined based on the wettability and impedance results. Findings: The electrochemical impedance for the patterned Si surfaces increased with increasing surface hydrophobicity, whereas the effective wetting area decreased. The intermediate wetting state (i.e. partial wetting model) was confirmed at the patterned Si surfaces, and the effective wetting area was theoretically estimated. The effective wetting area predicted from the electrochemical impedance agreed well with that predicted from the partial wetting model, thereby demonstrating the validity of the electrochemical impedance method for evaluating the effective wetting area at the hydrophobic solid–liquid interface

Preparation of High Lithium-Ion Conductive Ceramic

Lithium ionic conductive solid electrolyte discs based on NASICON-type LiB1+xBGaBxBTiB2-xB(POB4B)B3B (x = 0.1 - 0.9) were prepared by a wet-chemical route at 1173 - 1273K. Crystalline phase, density, and electrical conductivity of the sintered discs were systematically investigated. Single phase of LiTiB2B(POB4B)B3B systems were obtained at the calcination temperatures above 773K. Maximum conductivity 7.3 x 10P-4P S/cm at 303K and activation energy of 0.30eV were obtained for the LiB1.25BGaB0.25BTiB1.75B(POB4B)B3B discs sintered at 1223K

Preparation of High Lithium-Ion Conductive Ceramic

Lithium ionic conductive solid electrolyte discs based on NASICON-type LiB1+xBGaBxBTiB2-xB(POB4B)B3B (x = 0.1 - 0.9) were prepared by a wet-chemical route at 1173 - 1273K. Crystalline phase, density, and electrical conductivity of the sintered discs were systematically investigated. Single phase of LiTiB2B(POB4B)B3B systems were obtained at the calcination temperatures above 773K. Maximum conductivity 7.3 x 10P-4P S/cm at 303K and activation energy of 0.30eV were obtained for the LiB1.25BGaB0.25BTiB1.75B(POB4B)B3B discs sintered at 1223K

Improvement of Sensing Performance of Impedancemetric C₂H₂ Sensor Using SmFeO₃ Thin-Films Prepared by a Polymer Precursor Method

A sensitive an impedancemetric acetylene (C2H2) gas sensor device could be fabricated by using perovskite-type SmFeO3 thin-film as a sensor material. The uniform SmFeO3 thin-films were prepared by spin-coating and focusing on the effects of polymer precursor solutions. The prepared precursors and thin-films were characterized by means of thermal analysis, Fourier-transform infrared spectroscopy, ultraviolet⁻visible spectroscopy, X-ray diffraction analysis, scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that particle growth and increase in homogeneity of the prepared thin-film could be accelerated by the addition of acetyl acetone (AcAc) as a coordination agent in the polymer precursor solution. Moreover, the highly crystallized thin-film-based sensor showed good response properties and stabilities to a low C2H2 concentration between 0.5 and 2.0 ppm

Role of Recent PCR Tests for Infectious Ocular Diseases: From Laboratory-Based Studies to the Clinic

Infectious uveitis is a vision-threatening condition that requires prompt clinical diagnosis and proper treatment. However, rapid and proper diagnosis in infectious uveitis remains challenging. Several examination tests, including polymerase chain reaction (PCR) tests, are transitioning from laboratory-based basic research-level tests to bedside clinical tests, and recently tests have changed to where they can be performed right next to clinicians. In this review, we introduce an updated overview of recent studies that are representative of the current trends in clinical microbiological techniques including PCR tests for infectious uveitis