No abstract

Photocatalytic Z-scheme water splitting is a promising technology for solar energy conversion and storage, as it allows the individual production of H2 and O2. However, this method is generally hindered by undesirable backward reactions. We herein report the use of a novel VO2 +/VO2+ redox mediator to reveal that Fe–H–Cs–WO3 and Ru/SrTiO3:Rh photocatalyst surfaces exhibit selectivity toward O2 and H2 evolution reactions, respectively. The obtained hydrogen evolution rate of Ru/SrTiO3:Rh using VO2+ redox was 2-fold higher than those obtained using conventional redox reagents (i.e., Fe2+ or I– ions). Z-scheme water splitting by a (Ru/SrTiO3:Rh)–(Fe–H–Cs–WO3)–(VO2 +/VO2+) system was demonstrated both in the stepwise operation and in the conventional one-pot operation. The stepwise operation to produce H2 and O2 separately exhibited enhanced performance compared to the conventional one-pot operation. Finally, the solar to hydrogen energy conversion efficiency for the stepwise process using simulated solar irradiation was estimated to be 0.06%, which was demonstrated by the separated production of H2 and O2 for the first time.

A filtration theory for the power-law non-Newtonian fluids is developed on the basis of the extended Rabinowitsch-Mooney equation, and several definitions of non-Newtonian filtration characteristics are defined. The equations presented in this paper may be considered as equations applicable both for non-Newtonianfiltration and for conventional Newtonian filtration. Methods for evaluating the overall characteristics of non-Newtonian filtration are suggested by using the compression permeability data. In order to confirm the validity of the theory, constant pressure filtration experiments are carried out under various conditions of the flow behavior index Arranging from 0.404 to 0.504 and the filtration pressure/? from 1000 to 3000 G/cm2, and it is shown that the methods presented in this paper are valid. It is also shown that the average specific filtration resistance varies considerably with change in the TV-value of the power-law, and the cakes formed from non-Newtonian filtration of pseudo-plastic fluid are denser than those from usual Newtonian filtration.