Facile synthesis of Co(II)-BiOCl@biochar nanosheets for photocatalytic degradation of p-nitrophenol under vacuum ultraviolet (VUV) irradiation

In this study, cobalt-doped and biochar-cocatalyst bismuth oxychloride (Co(II)-BiOCl@biochar) photocatalysts were hydrothermally synthesized for the photodegradation of p-nitrophenol (PNP) and characterized via a series of analytical techniques. Results indicated that the addition of Co2+ and biochar to BiOCl resulted in 99.4% degradation of PNP in 90 min under vacuum ultraviolet (VUV) illumination. It was found that 5% doping of Co2+ and 30% loading of biochar significantly enhanced the photocatalytic performance of the as-prepared catalysts. After five cycles, the obtained hybrid catalysts still exhibited a good stability. Although the structure of BiOCl was not changed by the modification, the growth face changed from (001) to (110), which led to the narrow band gap, wide wavelength of the light source, effective separation of e-/h+ pairs, and high photocatalytic activity. The vast improvement was related to the formation of .OH, h+, e-, .O2-, and eaq- , which was confirmed by the radical-trapping experiments. Furthermore, a plausible mechanism for the photocatalysis of PNP over CO(II)BiOCl@biochar hybrid catalysts under VUV irradiation was also proposed.