Efficient overall photosynthesis of H2O2 by BTz@Mn0.2Cd0.8S S-scheme heterojunction

This study is led by Prof. Shaowen Cao (State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology).

The photosynthesis of hydrogen peroxide (H₂O₂) through the selective 2e^- oxygen reduction reaction (ORR) from O₂ and H₂O stands out as an environmentally sustainable and cost-effective method for generating this essential chemical. Unfortunately, the widespread application of most photocatalysts is impeded by their reliance on sacrificial agents. Therefore, photocatalytic H₂O₂ production is more attractive in pure water without any sacrificial agents.

“Thanks to the unique structure, step-scheme (S-scheme) heterojunctions can promote the spatial separation of photogenerated electrons and holes effectively and maximize the redox ability of the system. By delicately tuning the structures, S-scheme heterojunction can act as an ideal platform to support the simultaneous occurrence of photocatalytic 2e^- ORR and 4e^- water oxidation reaction (WOR).” Cao says.

Herein, a D-A conjugated polymer (BTz)@Mn_0.2Cd_0.8S (MCS) S-scheme heterojunction photocatalyst was synthesized by an electrostatic self-assembly method for non-sacrificial H₂O₂ production. The electron push-pull effect between benzene (D) and thiazole (A) in D-A conjugated polymers accelerates the efficient splitting of photogenerated excitons. The accumulated electrons of BTz and holes of MCS are applied respectively for the two-electron ORR and four-electron WOR in the S-scheme heterojunction, which achieves the utilization efficiency of carriers and the maximization of the redox capacity. A remarkable H₂O₂ yield of 5368 mmol g^-1 h^-1 with an apparent quantum yield of 4.5% at 420 nm was achieved. The outstanding photocatalytic performance of the prepared S-scheme heterojunction in H₂O₂ production can be attributed to the delicately tuned band structures and spatially separated redox centers. Combined with in situ irradiated X-ray photoelectron spectroscopy (ISIXPS), in situ diffuse reflectance infrared Fourier transformations spectroscopy (DRIFTS), and density functional theory (DFT) calculations, the interfacial charge transfer mechanisms and reaction pathways were uncovered. This work provides a new strategy for rational designing high-performance eco-friendly photocatalytic systems for artificial photosynthesis.

See the article:

Efficient overall photosynthesis of H₂O₂ by BTz@Mn_0.2Cd_0.8S S-scheme heterojunction