Hisao Yoshida

Hydrogen, a clean energy carrier, should be produced from not the irreproducible fossil fuels but renewable resources. Currently hydrogen is mainly produced by the reforming of petroleum and natural gas at high temperature, which consumes huge energy. Thus, development of an alternative hydrogen production method is absolutely imperative to mitigate the environmental and energy issues. Photocatalytic hydrogen production from water and renewable resources is one of the attractive systems, since i

Various efforts have been carried out to convert methane to more useful chemicals and hydrogen. However, due to its high stability, high energy is usually consumed for its conversion, which still remains as a problem to be solved. Recently, photocatalysis has been proposed to be one of the answers to break the thermodynamic barrier. This tutorial review provides a brief history about developments in the methane conversion and specially highlights the developments in the photocatalytic conversion

Photocatalytic reaction of CH4 gas with H2O vapor was examined over Pt/TiO2 around room temperature (ca. 323 K) in a flow reactor. H2 and CO2 were the main products, and only trace amounts of C2H6 and CO were also observed. After an induction period, the molar ratio of H2 to CO2 in the outlet gas became close to 4. Thus, the main reaction is suggested as the equation CH4 + 2H2O(g) → 4H2 + CO2, which can be referred to as photocatalytic steam reforming of methane (photocatalytic SRM), where the p

Quantitative determination of platinum oxidation state on supported platinum catalyst was examined by using Pt LIII-edge XANES spectra. The nano-sized platinum particles on the support were partially oxidized under oxidative atmosphere. The atomic ratio of oxygen to platinum (O/Pt) for these particles could be determined by the amount of desorbed oxygen in He carrier (O2-TPD) during elevated temperature. On the other hand, the XANES spectrum of the platinum catalysts oxidized under each correspo

X-Ray absorption near-edge structure (XANES) spectra at the Cu L and K edges have been measured for a series of Cu(II) compounds to clarify the factor affecting the chemical shift in the XANES spectra. The energy positions of the 2p1/2 → 3d and 2p3/2 → 3d transition peaks in the Cu L2,3 XANES spectra and the 1s → 3d transition peak (pre-edge peak) in the Cu K-edge XANES spectra were strongly influenced by the chemical states of the Cu(II), i.e., the coordination geometries (tetrahedral, octahedr