Stabilization of dispersed CuPd bimetallic alloy nanoparticles on ZIF-8 for photoreduction of Cr(VI) in aqueous solution

Nowadays, the Chromium (Cr(VI)) pollution is regarded as a serious threat to both the human health and environment. Therefore, developing an efficient catalyst to remove this pollution is an urgent task. As we know, photocatalytic degradation performance of Cr(VI) is severely hampered owing to its highly recombination efficiency of electrons and holes and lower adsorption activity. In this paper, bimetallic alloy nanoparticles decorated on ZIF-8 were synthesized using a sol-gel method for the photoreduction of Cr(VI) in aqueous solution. The CuPd@ZIF-8 catalyst was characterized in terms of specific surface area, surface morphology, and optical response using X-ray diffraction (XRD) spectrum, Raman spectrum, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), specific surface area and UV–vis diffuse reflectance (DRS) spectrum. The as-obtained CuPd@ZIF-8 catalyst exhibited excellent photoreduction activity for the reduction of Cr (VI), compared to that of pristine ZIF-8 nanoparticles. Furthermore, the CuPd@ZIF-8 catalyst containing 5 wt% CuPd bimetallic nanoparticles showed the highest photocatalytic activity, where 89% reduction of Cr(VI) (20 ppm) reduction was achieved within 60 min. The as prepared CuPd@ZIF-8 catalyst provided a high specific surface area and charge transfer rate, which impeded the recombination of the generated electrons and holes. Moreover, the stability of the CuPd@ZIF-8 catalyst was tested and photocatalytic activity was maintained at ˃90% after four cycles. In addition, the proposed mechanism is explained thoroughly.