S-scheme Mo-WO3/CeO2 microspheres photoanode enabling high-efficiency power generation in H2O2 photoelectrochemical cell

This study introduces a significant advancement in sustainable energy conversion through a novel hydrogen peroxide (H₂O₂) photoelectrochemical cell system. By integrating an oxygen vacancy-rich Mo-doped WO₃ (Mo-WO₃)/CeO₂ S-scheme heterojunction photoanode with a cornstalk-derived porous carbon/Fe-phthalocyanine (PC/Fe^IIPc) cathode, the system achieves efficient solar-driven H₂O₂ production and direct electricity generation via in situ H₂O₂ fuel utilization. The Mo-WO₃/CeO₂ heterojunction synergizes with Mo doping-induced oxygen vacancies (OVs) and S-scheme charge transfer pathways, significantly enhancing light absorption and charge separation. This design enables a remarkable H₂O₂ yield of 0.044 M and a maximum power density of 5.79 mW cm⁻², surpassing the pristine WO₃-based cell by 4 and 2.55 times, respectively. Additionally, the cell exhibits robust dark-phase energy storage with a capacitance of 57834 mF cm⁻², which has a 54% capacity retention over 12 h. Combined experimental and theoretical analyses reveal that oxygen vacancies in Mo-WO₃ act as electron traps, while the S-scheme heterojunction’s internal electric field directs charge flow, collectively suppressing recombination and preserving redox potentials. This work establishes a green paradigm for simultaneous solar energy harvesting, chemical fuel storage, and on-demand electricity generation.