Stable all-solid-state Z-scheme heterojunction Bi2O3-Co3O4@C microsphere photocatalysts for recalcitrant pollutant degradation

We present a strategy for the modification of an ion-exchange resin (D113) as an inexpensive carbon source to obtain a macrospherical photocatalyst precursor that can be transformed into a stable all-solid-state Zscheme heterojunction catalyst (denoted Bi2O3-Co3O4@C). X-ray diffractometry and Fourier transform infrared and Raman spectroscopy measurements confirmed the presence of highly graphitized carbon in the complex. Significantly, the cost of the as-prepared material was only 1/200 of that of commercial carbon nanotubes and 1/80 of that of graphene oxide. Aided by the organic carbon source, Bi2O3-Co3O4 @C showed an enhanced light absorption, hindered electron-hole recombination, and an enhanced photocurrent response. Under simulated solar irradiation, Bi2O3-Co3O4 @C (20 mg/L) showed degradation efficiencies of 100%, 47.52%, 94.28%, and 100% for methylene blue, rhodamine B, tetracycline, and Cr(VI), respectively, after 120 min. Herein, the highest turnover frequency (TOF) obtained under irradiation was 2.5 h-1 for Cr(VI). Further, the degradation efficiency for methylene blue trihydrate remained 91.46% after five cycles, indicating significantly higher stability than that of a catalyst prepared without graphitic carbon. The optimized band structure and photocatalytic mechanism of Bi2O3-Co3O4@C were determined based on ultraviolet-visible measurements and plane-wave density functional theory calculations in VASP. The findings of this study indicate the promise of the Bi2O3-Co3O4@C macrospheres for industrial applications based on their photocatalytic performance, high stability, low cost, and suitable particle size.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

We propose a strategy to modify an ion-exchange resin (D113) as a low-cost carbon source to achieve a macrospherical photocatalyst precursor, which can be converted into a stable all-solid-state Z-scheme heterojunction catalyst (Bi2O3-Co3O4@C). The as-prepared material has highly graphitized carbon and costs only a fraction of commercial carbon nanotubes and graphene oxide. The Bi2O3-Co3O4@C exhibits enhanced light absorption, weakened electron-hole recombination, and improved photocurrent response with the aid of the organic carbon source. Under simulated solar irradiation, it demonstrates high degradation efficiencies for various pollutants. The study also provides insights into the band structure and photocatalytic mechanism of Bi2O3-Co3O4@C.