Reduction of Superoxide Radical Intermediate by Polydopamine for Efficient Hydrogen Peroxide Photosynthesis

The synthesis of hydrogen peroxide through artificial photosynthesis is a green and promising technology with advantages in sustainability, economy and safety. However, superoxide radical (⋅O₂ ^-), an important intermediate in photocatalytic oxygen reduction to H₂O₂ production, has strong oxidizing properties that potentially destabilize the catalyst. Therefore, avoiding the accumulation of ⋅O₂ ^- for its rapid conversion to H₂O₂ is of paramount significance in improving catalyst stability and H₂O₂ yield. In this work, a strategy was developed to utilize protonated groups for the rapid depletion of converted ⋅O₂ ^-, thereby the efficiency of photocatalytic synthesis of H₂O₂ from CN was successfully enhanced by 47-fold. The experimental findings demonstrated that polydopamine not only improved carrier separation efficiency, and more importantly, provided the adsorption reduction active site for ⋅O₂ ^- for efficient H₂O₂ production. This work offers a versatile approach for synthesizing efficient and stable photocatalysts.