Carbon Quantum Dot Conjugated Copper(II) Phthalocyanine Integrating BiVO4 Semiconductor for Photocatalytic Water Oxidation

Photocatalytic water splitting as one of the most promising strategies has attracted widespread attention to solve the energy crisis, in which water oxidation was the bottleneck because of the complex four-electron reaction process. Bismuth vanadate (BiVO4), as a widely studied light-harvesting semiconductor in photocatalytic water oxidation, suffers from a low separated rate of photogenerated charge carriers and poor stability. Herein, carbon quantum dots (CQDs) and copper(II) phthalocyanine (CuPc) form tight conjugate systems by pi-pi electron stacking, which then coupled with BiVO4 by a hydrothermal method to construct a water oxidation photocatalyst BiVO4/CQDs/CuPc. The hybrid catalyst exhibits efficient photocatalytic water oxidation activity due to the presence of a Z-scheme transfer mechanism, in which the O-2-evolved amount for an optimal sample is about 5.1 times (371.8 mu mol g(-1) h(-1)) higher than that of bare BiVO4. The apparent quantum efficiency (AQE) in 1 h is 36.8%. Additionally, in this Z-scheme system, CuPc coupled with BiVO4 enhances the separation efficiency of photogenerated charge carries, where CQDs play a role in the electron shuttle, promoting the electron transfer rate between CuPc and BiVO4. Our study demonstrates that CQDs and CuPc are introduced to couple with the inorganic semiconductor BiVO4 to fabricate efficient ternary composite water oxidation photocatalysts.

Automated summary

Carbon quantum dots and copper(II) phthalocyanine are introduced to construct a ternary composite water oxidation photocatalyst BiVO4/CQDs/CuPc, which significantly enhances the water oxidation activity of the catalyst through a Z-scheme transfer mechanism.