Scalable Photoelectrochemical Cell for Overall Solar Water Splitting into H₂ and H₂O₂

Aqueous photoelectrochemical (PEC) cells have been considered a scalable technology to convert solar energy to H 2 but still suffer from sluggish water oxidation kinetics and downstream gas separation. Here we demonstrate a PEC water splitting into H 2 O 2 and H 2 by employing a CaSnO 3 /SrTiO 3 /BiVO 4 (CSO/STO/BVO) photoanode to simultaneously address the above two problems. The CSO as cocatalyst selectively oxidizes water to H 2 O 2 with a Faradaic efficiency of 90%, while the STO interlayer promotes the charge separation by an inner polarization field. The scalability potential is demonstrated by 144 cm 2 array panel reactors, which achieve an industrial-scale peak photocurrent of 0.11 A under a natural irradiance of 862 W·m –2 . The proposed incidence-inclination angle analysis finds the optimum operation for array panel reactors to achieve the highest land-to-photocurrent efficiency. This renovated view of the PEC cell design may enable further optimization of industrial applications.