Dual vacancy-regulated S-shaped heterojunction full spectrum photoanode in situ self-supply H2O2-driven activation: Cathode-anode cooperative photoelectrocatalysis system efficiently generates 1O2 for water purification

Photoelectrocatalytic (PEC) in situ hydrogen peroxide (H 2 O 2 ) production offers a green strategy for activating singlet oxygen ( 1 O 2 ) and degrading refractory organic pollutants. However, it suffers from low cathode yield, sluggish anode kinetics, mass-transfer losses, and low selectivity for 1 O 2 . This study ingeniously designed an S-O double vacancy β-In 2 S 3 -Er/Yb@WO 3 -Ov S-type heterojunction full-spectrum photoanode, offered new perspectives on in situ oxygen reduction at the photoanode for H 2 O 2 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 H 2 O 2 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 1 O 2 generation. β-In 2 S 3 -Er/Yb@WO 3 -Ov photoanode realized in-situ oxygen reduction reaction-induced H 2 O 2 production and cathodic H 2 O 2 activation simultaneously. Both routes yield ·OOH/·O 2 - intermediates, which were oxidized by holes to form 1 O 2 , thereby enabling efficient carbamazepine removal (98.4%, k app  = 0.093 min -1 ), efficient 1 O 2 production (53.13 μmol L -1 min -1 ), and low energy consumption (0.155 kWh m -3 -log). This work presents an advanced PEC strategy for the synergistic synthesis of H 2 O 2 and 1 O 2 , offering a promising approach for high-efficiency environmental remediation.