Synergism of Co/Na in BiVO₄ microstructures for visible-light driven degradation of toxic dyes in water

In this work, we report a synergism of Co/Na in Co@Na-BiVO₄ microstructures to boost the photocatalytic performance of bismuth vanadate (BiVO₄) catalysts. A co-precipitation method has been employed to synthesize blossom-like BiVO₄ microstructures with incorporation of Co and Na metals, followed by calcination at 350 °C. The structure and morphology of the as-prepared photocatalysts are characterized by XRD, Raman, FTIR, SEM, EDX, AFM, UV-vis/DRS and PL techniques. Dye degradation activities are evaluated by UV-vis spectroscopy, in which methylene blue, Congo red and rhodamine B dyes are chosen for comparative study. The activities of bare BiVO₄, Co-BiVO₄, Na-BiVO₄, and Co@Na-BiVO₄ are compared. To evaluate the ideal conditions, various factors that affect degradation efficiencies have been investigated. The results of this study show that the Co@Na-BiVO₄ photocatalysts exhibit higher activity than bare BiVO₄, Co-BiVO₄ or Na-BiVO₄. The higher efficiencies were attributed to the synergistic role of Co and Na contents. This synergism assists in better charge separation and more electron transportation to the active sites during the photoreaction.