Boosted photocatalytic performance of CO₂ reduction and RhB oxidation over CaCO₃/g-C₃N₄ composite with highly effective holes transfer

The separation and migration of photoexcited holes are of crucial importance to the enhanced photocatalytic performance of composite. To arouse much more concern about them, the efficient and steady CaCO₃/g-C₃N₄ composites with different mass percents of CaCO₃ were innovatively designed by a green approach for environmental remediation in the present study. The crystalline structure, band structure, micromorphology and heterojunction structure of these prepared samples were synergistically characterized by employing different technologies. An obviously improved visible-light catalytic performance of CO₂ reduction and RhB oxidation for the composite was possessed in comparison with bare g-C₃N₄. The perfect CaCO₃ ratio among these composites was 20%. The heterojunction constructed in the system and negatively charged CaCO₃ as a highly effective holes transfer promoter accelerate the holes migration from the valance band of g-C₃N₄ to that of CaCO₃. Accordingly, these bring about efficient carriers separation and boosted photocatalytic performance of the composite. This work can not only offer valuable insights into the design of other novel composites with efficient holes transfer, but also provide a method to solve the undesirable photocatalytic performance of g-C₃N₄ in the application domain of renewable energy and ecological governance.

The enhanced performance of the composite is primarily attributed to the highly efficient charge separation in the CaCO₃/g-C₃N₄ system, because the heterojunction constructed between them and negatively charged CaCO₃ accelerate the fast transfer of photoinduced h⁺ from VB of g-C₃N₄ to that of CaCO₃.