A metal-free photocatalyst for highly efficient hydrogen peroxide photoproduction in real seawater

Artificial photosynthesis of H2O2 from H2O and O-2, as a spotless method, has aroused widespread interest. Up to date, most photocatalysts still suffer from serious salt-deactivated effects with huge consumption of photogenerated charges, which severely limit their wide application. Herein, by using a phenolic condensation approach, carbon dots, organic dye molecule procyanidins and 4-methoxybenzaldehyde are composed into a metal-free photocatalyst for the photosynthetic production of H2O2 in seawater. This catalyst exhibits high photocatalytic ability to produce H2O2 with the yield of 1776 mu mol g(-1)h(-1) (lambda >= 420nm; 34.8mWcm(-2)) in real seawater, about 4.8 times higher than the pure polymer. Combining with in-situ photoelectrochemical and transient photovoltage analysis, the active site and the catalytic mechanism of this composite catalyst in seawater are also clearly clarified. This work opens up an avenue for a highly efficient and practical, available catalyst for H2O2 photoproduction in real seawater. It is a challenge to produce hydrogen peroxide in seawater by photocatalysis. Here, the authors design and synthesize a metal-free photocatalyst based on carbon dots with a salt-protective electron sink effect, which exhibits enhanced hydrogen peroxide photoproduction in real seawater.

Automated summary

Artificial photosynthesis of H2O2 from water and oxygen has attracted widespread interest, but most photocatalysts face salt-deactivation effects. In this study, a metal-free photocatalyst based on carbon dots was synthesized for H2O2 photoproduction in seawater, showing a significantly higher yield compared to pure polymers. In-depth analysis revealed the active sites and catalytic mechanism of this composite catalyst in seawater, providing a highly efficient and practical catalyst for H2O2 photoproduction.