Abstract:
Photoelectrochemical (PEC) water splitting is an emerging technology to store the solar energy in the chemical bonds of molecular hydrogen. Among several photo electrodes used for PEC water splitting, α-Fe2O3 is a promising material due to its suitable bandgap, chemical stability, and abundance. Despite these, the position of its conduction band does not allow spontaneous movement of photo-generated electrons to cause the water reduction. This demands the application of a minimum electrical bias of ∼1.5 V vs. SHE to increase the energy of the conduction band such that it will be energetically above the H2O/H2 redox level. We show that by utilizing the energy of neutralization, the minimum electrical voltage required for PEC water splitting can be brought down to ∼0.8 V. By employing an OH−/H+dual-ion configuration. OH−/H+dual-ion assisted PEC water splitting required only 0.95 V to produce a current density of 10 mA/cm2, and for achieving the same rate in a conventional symmetric ion configuration, at least a doubling of the applied electrical bias (∼1.8 V) is required.