Bi2MoO6 nanoflower-like microsphere photocatalyst modified by boron doped carbon quantum dots: Improving the photocatalytic degradation performance of BPA in all directions

Abstract

Bi-based semiconductor photocatalyst represented by Bi2MoO6 (BMO) has obvious advantages in the degradation of bisphenol A (BPA), but three prominent problems that restrict the improvement of photocatalytic performance, namely, insufficient solar absorption, less active sites and serious photogenerated carrier recombination, need to be solved urgently. For this reason, we specially designed a simple structure of B-doped carbon quantum dots (BCQDs) modified BMO nanoflower-like microsphere composite to improve the photocatalytic performance of the system from the above three dimensions. The optimized BCQDs/BMO sample completely degraded BPA within 120 min under simulated sunlight, corresponding to an apparent constant of 0.03453 min−1, while the control sample of CQDs/BMO without B doping only degraded about 84 % of BPA within 160 min, with an apparent coefficient of 0.01138 min−1. Even after filtering out UV components below 400 nm, the degradation performance of the optimal composite catalyst did not decrease. The improved catalytic performance comes from the excellent up-conversion luminescence performance and good electron storage capacity of CQDs on the one hand, and the introduction of B on the other hand can adjust the surface structure of CQDs to generate more active sites and functional interfaces to further promote the catalytic reaction. Free radical trapping and electron spin resonance (ESR) tests have shown that·OH and·O2- are the main active substances in the degradation of BPA. The current BCQDs/BMO catalysts, despite their simple structure, can simultaneously improve the catalytic performance from the three important aspects mentioned above, which will guide the design of others semiconductor based photocatalysts.