Bismuth-containing layered double hydroxide as a novel efficient photocatalyst for degradation of methylene blue under visible light

Layered double hydroxide (LDH)-based photocatalysts have emerged as a very promising candidate to replace TiO₂, owing to their unique layered structure, tunable band gaps, low cost, ease of scale-up, and good photocatalytic activity. Bismuth-doped ZnCr-LDH was studied as photocatalyst in the photodegradation of methylene blue (MB). The structure and morphology of ZnCr-LDH and ZnCrBi-LDH were characterized using a different mode of delegated tools, e.g., FTIR, XRD, UV–Vis, FESEM–EDX, and TEM measurements. FESEM and TEM image of the synthesized LDHs showed that the synthesized LDH is smooth overlapping crystals, and they are approximately in hexagonal form. The material was found to be a good photocatalyst for degradation of methylene blue in visible light, and the results showed that the photocatalytic activity of ZnCrBi-LDH sample is higher than of ZnCr-LDH sample. According to the kinetic data, the reaction rate constant of ZnCrBi-LDH is approximately four times higher than the apparent reaction rate constant of ZnCr-LDH. The catalytic activity was retained even after four methylene blue degradation cycles, indicating that the LDH could be an important addition to the field of wastewater treatment.