Efficient hydrogen peroxide photogeneration over GaOOH/In(OH)3 composites via the half-reaction of tetracycline oxidation

The photocatalytic generation of hydrogen peroxide (H 2 O 2 ) using artificial synthetic methods is promising. However, the sluggish hole-induced water oxidation half-reaction that hinders charge separation severely limits H 2 O 2 generation efficiency. This study used the oxidation half-reaction of tetracycline (C 22 H 24 N 2 O 8 , TC) to accelerate charge separation over GaOOH/In(OH) 3 composites with Type II heterojunctions under sunlight irradiation to increase the H 2 O 2 generation efficiency. The results demonstrated that the H 2 O 2 generation efficiency significantly increased from 74.7 to 389.8 µmol L −1 h −1 as the TC degradation efficiency increased from 0.02 to 0.37 mg L −1 h −1 . Radical quenching experiments further indicated that TC degradation consumed holes, increasing the electron formation rate and enhancing H 2 O 2 generation. A comparison with density functional theory calculations revealed that H 2 O 2 generation was a one-step 2-electron route (O 2  + 2e − + 2H + → H 2 O 2 ). These findings are expected to provide new strategies for promoting photocatalytic synthesis of H 2 O 2 .