Carbonized Polymer Dots/Bi/β-Bi 2 O 3 for Efficient Photosynthesis of H 2 O 2 via Redox Dual Pathways.

A novel heterojunction photocatalyst of carbonized polymer dots (CPDs)/Bi/β-Bi ₂ O ₃ is successfully synthesized via a one-pot solvothermal method by adjusting the reaction temperature and time. As a solvent and carbon source, ethylene glycol not only supports the conversion of Bi ³⁺ to β-Bi ₂ O ₃ but also undergoes its polymerization, cross-linking, and carbonization to produce CPDs. In addition, partial Bi ³⁺ is reduced to Bi by ethylene glycol. As a result, the CPDs and Bi are deposited in situ on the surface of β-Bi ₂ O ₃ microspheres. There are four built-in electric fields in the CPDs/Bi/β-Bi ₂ O ₃ system, namely, the n-type semiconductor β-Bi ₂ O ₃ /H ₂ O interface, the p-type CPDs/H ₂ O interface, the ohmic contact between Bi and β-Bi ₂ O ₃ , and the Schottky junction between Bi and CPDs. Under the action of four built-in electric fields, the Z-type charge separation mechanism is formed. It promotes the effective separation of the photogenerated electron-hole and greatly improves the yield of H ₂ O ₂ . Under irradiation for 2 h, the H ₂ O ₂ production is 1590 μmol g ^-1 h ^-1 . The solar energy to H ₂ O ₂ conversion efficiency is 0.11%.