Dual vacancy-regulated S-shaped heterojunction full spectrum photoanode in situ self-supply H₂O₂-driven activation:...

Photoelectrocatalytic (PEC) in situ hydrogen peroxide (H₂O₂) production offers a green strategy for activating singlet oxygen (¹O₂) and degrading refractory organic pollutants. However, it suffers from low cathode yield, sluggish anode kinetics, mass-transfer losses, and low selectivity for ¹O₂. This study ingeniously designed an S-O double vacancy β-In₂S₃-Er/Yb@WO₃-Ov S-type heterojunction full-spectrum photoanode, offered new perspectives on in situ oxygen reduction at the photoanode for H₂O₂ generation, and presented a dual-electrode cooperative PEC system. In the experiment, double vacancies at the photoanode acted as electron traps, accumulating electrons. Meanwhile, an applied bias voltage, more electrons on the surface, and weakly acidic and oxygen-permeable conditions the electrons trapped by vacancies, together with conduction band electrons, were conducive to driving the in-situ two-electron oxygen reduction reaction to H₂O₂ formation at the photoanode. O vacancies dominated interfacial adsorption and catalysis, while S vacancies served as electron traps for charge separation, forming a complementary synergy. Coupled with charge modulation at the S-scheme heterojunction interface, accelerating photogenerated carrier separation and preserved highly reactive holes, providing key conditions for ¹O₂ generation. β-In₂S₃-Er/Yb@WO₃-Ov photoanode realized in-situ oxygen reduction reaction-induced H₂O₂ production and cathodic H₂O₂ activation simultaneously. Both routes yield ·OOH/·O₂^- intermediates, which were oxidized by holes to form ¹O₂, thereby enabling efficient carbamazepine removal (98.4%, k_app = 0.093 min^-1), efficient ¹O₂ production (53.13 μmol/(L·min)), and low energy consumption (0.155 kWh/m³-log). This work presents an advanced PEC strategy for the synergistic synthesis of H₂O₂ and ¹O₂, offering a promising approach for high-efficiency environmental remediation.