Controllable synthesis of BiVO₄ photocatalysts with distinct morphology toward different dyes degradation in the presence of peroxydisulfate

BiVO₄ photocatalysts with distinct morphology were solvothermally prepared by regulating the pH of precursor solution. The physicochemical properties of BiVO₄ catalysts were characterized using XRD, SEM, EDS, FT-IR and UV-Vis DRS. With the assistance of peroxydisulfate (PDS), as-obtained BiVO₄ could effectively degrade the cationic dye rhodamine B (RhB) and the anionic dye methyl orange (MO) under visible-LED-light illumination. RhB degradation obeys the first-order kinetic, while MO degradation complies with the second-order kinetic. Short stick-like BiVO₄ (named as BiVO₄-1) showed the best RhB degradation efficiency, and sheet-like BiVO₄ (named as BiVO₄-9) had the highest MO degradation rate. The influence of some important operating factors (PDS dose, BiVO₄ dosage, temperature, inorganic anions and humic acid) on the degradation of RhB and MO were discussed. In the BiVO₄-1/PDS/Vis system, the free radical pathway (O₂^•‒, SO₄^•‒, •OH) and the non-radical pathway (¹O₂ and h⁺) acted together to realize the degradation of RhB; however, in the BiVO₄-9/PDS/Vis system, MO degradation was mainly dominated by the non-radical oxidation pathway (¹O₂ and h⁺).