Solid acids accelerate the photocatalytic hydrogen peroxide synthesis over a hybrid catalyst of titania nanotube with carbon dot

Photocatalytic synthesis of hydrogen peroxide (H 2 O 2 ) from water and oxygen is an alternative route for clean energy storage and chemical synthesis, but still having problems with insufficient H 2 O 2 productivity and solar-to-chemical energy conversion efficiency. Herein, we reported a hybrid catalyst of proton-form titania nanotube with carbon dot (HTNT-CD) that is highly efficient for the production of H 2 O 2 under visible-light irradiation (λ > 420 nm, H 2 O 2 productivity at 3.42 mmol g cat −1 ⋅h −1 ), outperforming the titania catalysts containing noble metals and the carbon nitride catalysts reported previously. Multiple studies demonstrate that the protons on the HTNT-CD are crucial for the production of H 2 O 2 by efficiently accelerating the half reaction of molecular oxygen reduction to form H 2 O 2 , and effectively hindering H 2 O 2 decomposition under the irradiation conditions. This HTNT-CD catalyst gives solar-to-H 2 O 2 apparent energy conversion efficiency at 5.2%, which is even 4.9 times of that (1.06%) over the catalyst derived from commercial P25 and CDs. More importantly, the HTNT-CD is stable, giving high H 2 O 2 productivity in the continuous recycle tests.