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 Z-scheme 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. [Display omitted] •Z-scheme heterojunction was constructed under the mediation of graphitized carbon.•Bi2O3-Co3O4 @C optimized structure promoted light absorption and photocurrent response.•Bi2O3-Co3O4 @C showed better photocatalytic performance than binary and pure samples.•Combined with DFT calculation, all-solid Z-scheme mechanism of reaction was proposed.