The solar fuels generator includes an ionically conductive separator between a gaseous first phase and a second phase. A photoanode uses one or more components of the first phase to generate cations during operation of the solar fuels generator. A cation conduit is positioned provides a pathway along which the cations travel from the photoanode to the separator. The separator conducts the cations. A second solid cation conduit conducts the cations from the separator to a photocathode.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
 This invention was made with government support under DE-SC000493/T-105567 awarded by the Department of Energy (JCAP). The government has certain rights in the invention.