Synthesizing Co3O4-BiVO4/g-C3N4 heterojunction composites for superior photocatalytic redox activity

In this study, a novel coral-like Co3O4-BiVO4/g-C3N4 ternary composite catalyst was successfully synthesized via high temperature polymerization and controlled hydrothermal reaction. In the Co3O4-BiVO4/g-C3N4 ternary hybrid system, the bulk Co3O4 particles were uniformly dispersed on the coral-like BiVO4 nanosheet, which not only enhanced to increase the response range and absorption to visible light, also contributed to suppress the recombination of photogenerated electron holes. The introduction of flocculent g-C3N4 increased the specific surface area of the catalytic system while accelerating the transmission efficiency of photogenerated carriers. After being illuminated for 90 min under the visible light, the degradation efficiency of pure BiVO4 and g-C3N4 catalysts were 81% and 80.2%, respectively. And the two binary catalysts, Co3O4-BiVO4 and BiVO4/g-C3N4 composite catalyst, performed the higher photocatalytic activity, which reached 94.8% and 96.8%, while ternary catalyst Co3O4-BiVO4/g-C3N4 composite catalyst showed the highest photocatalytic activity, the removal rate of KN-R was up to 99.6% after being irradiated for only 30 min with visible-light. Even more, its optical and electrochemical properties were greatly improved, making it as a forceful candidate for practical photocatalysts under visible light. In summary, this work not only provided a highly efficient heterojunction-structured visible-light photocatalyst, but also supplied a novel method to diminish the photo-carriers recombination.