where JPEC is the measured photocurrent density, Jabs is the photon absorption efficiency, ηsep is the charge separation efficiency, and ηinj is the charge injection efficiency. Figure shows the reflectance and absorbance of both Sb2Se3 samples, indicating almost identical photon absorption efficiency. The value of ηinj for both Sb2Se3 photocathodes can be assumed to be equal due to the same Pt co-catalyst loaded by sputtering. Therefore, we identify that the photocurrent enhancement for the Sb2Se3-H photoelectrode derives from the improved ηsep, i.e., less recombination occurs in the Sb2Se3-H device.