  The low conversion rate and efficiency always weaken the performance of
thermochemical water-splitting reaction. Herein, we, for the first time,
conducted the thermodynamic study of a hydrogen permeable membrane (HPM) in an
isothermal thermochemical water-splitting reaction driven by solar energy,
which has showed a sharply enhanced conversion rate of 87.8% at 1500 oC and
10-5 atm at permeated side (versus 1.26% with oxygen permeation membrane).
According to thermodynamic analysis, the first-law thermodynamic efficiency can
reach as high as 59.1%. When taking solar-to-electric efficiency and vacuum
pump efficiency into account (for converting separation work into solar
energy), we simulated the appreciable efficiency of 3.05% at 1500 oC. The
numerical model will provide guidance for the actual production of hydrogen by
high temperature solar water splitting. Such novel work manifests the great
significance of constructing a HPM reactor for efficient solar thermochemical
water splitting, which shows a novel approach for high-temperature solar water
splitting.
