Aqueous glass-coated CsPbI3 quantum dots implanted in g-C3N4 nanosheets for efficient photocatalytic water splitting and H2O2 generation

Abstract

Increasing visible light harvesting and improving charge carrier separation and transfer efficiency are crucial for photocatalytic H2O2 generation using graphitic carbon nitrides (g-C3N4) based catalysts. In this paper, a high temperature solid synthesis was developed to create water stable SiO2 glass coated CsPbI3 (CsPbI3@SiO2) quantum dots (QDs) with high brightness and extraordinary stability. These CsPbI3@SiO2 QDs were implanted in superior thin g-C3N4 nanosheets via a solvothermal synthesis. The red-emission of CsPbI3 QDs and the blue emission of g-C3N4 nanosheets were quenched after incorporation to confirm that photogenerated electron transition occurred. The further polymerization of g-C3N4 during solvothermal treatment resulted in CsPbI3@SiO2/g-C3N4 with well-developed interface to improve the charge transfer efficiency. A type II heterostructure formed after CsPbI3@SiO2 QDs incorporated with g-C3N4 nanosheets. The heterostructure revealed enhanced photocatalytic H2 and H2O2 generation, in which the evolution rate of H2O2 was 2454.4 μmol·g−1·h−1 while the photocatalytic H2 generation rate was 2463.1 μmol·g−1·h−1. The mechanism test indicated that the photocatalytic production of H2O2 was carried through a two-step single-electron redox process. Superoxide radicals were important intermediates for the generation of H2O2. This study provides a new scheme for the preparation of g-C3N4 based heterojunction photocatalyst for efficient photocatalytic production of H2O2 and H2.